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P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 C 2002) Journal of Genetic Counseling, Vol. 11, No. 2, April 2002 (° Fabry Disease in Genetic Counseling Practice: Recommendations of the National Society of Genetic Counselors Robin L. Bennett,1,9 Kimberly A. Hart,2 Erin O’Rourke,3 John A. Barranger,3 Jack Johnson,4 Kay D. MacDermot,5 Gregory M. Pastores,6 Robert D. Steiner,7 and Ravi Thadhani8 The objective of this document is to provide health care professionals with recommendations for genetic counseling and testing of individuals with a suspected or confirmed diagnosis of Fabry disease, with a family history of Fabry disease, and those identified as female carriers of Fabry disease. These recommendations are the opinions of a multicenter working group of genetic counselors, medical geneticists, and other health professionals with expertise in Fabry disease counseling, as well as an individual with Fabry disease who is a founder of a Fabry disease patient advocacy group in the United States. The recommendations are U.S. Preventive Task Force Class III, and they are based on clinical experience, a review of pertinent English-language articles, and reports of expert committees. This document reviews the genetics of Fabry disease, the indications for genetic testing and interpretation of results, psychosocial considerations, and references for professional and patient resources. These recommendations should not be construed as 1 Department of Medicine, Division of Medical Genetics,University of Washington,Seattle,Washington. 2 Department of Pediatrics, Division of Medical Genetics, University of California, San Francisco, California. 3 Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania. 4 Fabry Support and Information Group, Concordia, Missouri. 5 Department of Medicine, Addenbrooke’s Hospital, Cambridge, United Kingdom. 6 Department of Neurology and Pediatrics, New York University School of Medicine, New York, New York. 7 Departments of Pediatrics and Molecular and Medical Genetics, Child Development and Rehabilitation Center, Dorenbecher Children’s Hospital, Oregon Health & Science University, Portland, Oregon. 8 Department of Medicine and Renal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts. 9 Correspondence should be directed to Robin L. Bennett, MS, CGC, University of Washington Medical Center, Box 357720, Seattle, Washington 98195-7720; e-mail: [email protected]. 121 C 2002 National Society of Genetic Counselors, Inc. 1059-7700/02/0400-0121/1 ° P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 122 11:37 Style file version Nov. 19th, 1999 Bennett et al. dictating an exclusive course of management, nor does use of such recommendations guarantee a particular outcome. The professional judgment of a healthcare provider, familiar with the facts and circumstances of a specific case, will always supersede these recommendations. KEY WORDS: enzyme therapy; Fabry disease; genetic counseling; genetic testing; National Society of Genetic Counselors; practice guidelines. INTRODUCTION The following case scenarios were collected from a support group for individuals affected by Fabry disease. Vignette 1—Eric Growing pain was the diagnosis; I remember one of the visits when my son was 11 years old. A physician brought my son close to the lighted panel showing the side view of the x-ray of his foot. He pointed to the white ends of the bones near Eric’s heel and said “See this bone growth right here? This is definitely what’s causing the pain.” Made sense to him, and he was the expert. Made sense to me. Made sense to my son. But from that point on, making sense was not a logical way of thinking. Not only did the pain continue, other things kept happening to him during the following years. Hand pain was a problem along with the foot pain. When he was ill or ran a fever, the pain was so much worse—but of course, doesn’t everyone suffer this with a fever? When he would sit because his feet hurt, I would push him just a little more, in the hope that he would walk right out of the pain. “Ignore it and maybe it would go away” became my motto. Eventually, Crohn disease was ruled-out as the cause of his abdominal problems, but we still had no diagnosis. Fabry disease was known to be in the family. After learning more about Fabry disease we requested testing. Finally, a correct diagnosis was made. Eric was 25 years old. At last he began to talk about the suffering he had endured all those years. Vignette 2—Jill My earliest memories of severe pain go back to about age 11. The aching and throbbing pain typically would be in my hands and feet most days, but also in my arms and legs during some days, and always during serious bouts, or attacks. About every three weeks I would develop a fever, and then the very intense pain would begin. I’ll always remember how as a child I would look at my hands and feet and not understand how they could feel as though they were on fire yet not show any signs of redness, or look any different than usual. With the burning came severe throbbing and aching, as well as stabbing (piercing) pains that would start in my hands and feet, and then move throughout my arms and legs. The stabbing would start at a low intensity and then, within a second, build to an unbearable intensity, and this type of pain would happen continually throughout the attack. I remember crying and wanting to scream from the pain. I would be bedridden during these attacks, which would last from 24 to 48 hours. I’d have other symptoms during these bouts that seemed flu-like, with nausea, vomiting, headache, and just a general feeling of illness. Shortly after the attack, I would resume my normal activities. Over the years there were many diagnoses: chronic mononucleosis, adult Still disease, lupus, arthritis, bronchitis and pneumonia. The usual treatment was aspirin or antibiotics. With many years of frustration, and physicians who provided no real relief, I was frustrated P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 Genetic Counseling: Fabry Disease 123 and went to my doctors as little as possible. I finally was correctly diagnosed with Fabry disease at the age of 30 years. These vignettes dramatically illustrate the need for increased awareness of Fabry disease among health professionals to facilitate early diagnosis, as well as the importance of recommendations for genetic counseling for Fabry disease to educate genetic counselors and other health professionals about this rare, and now potentially treatable inherited condition. PURPOSE The following recommendations are intended to assist health care professionals who provide genetic counseling for individuals and families in whom the diagnosis of Fabry disease is suspected or has been confirmed. We review the genetics of Fabry disease, indications for genetic testing and interpretation of results, psychosocial considerations, and references for professional and patient resources. METHOD AND CONSENSUS PROCESS The authoring subcommittee consisted of experts in genetic counseling (EO, KAH, RLB), biochemical genetics (GMP, JAB, KDM, RDS), clinical/medical genetics (GMP, JAB, KDM, RDS), clinical molecular genetics (GMP), renal disease (RT), pediatrics (GMP, RDS), and internal medicine (KDM, RT). Input was also sought from a patient advocacy group for Fabry disease (JJ). A literature search for relevant English-language medical articles published between January 1985 and June 2001 was performed using the MEDLINE and PUBMED databases. Bibliographies of articles were also reviewed. Articles were reviewed with particular attention to genetic counseling and diagnostic issues. The literature reviewed was based on clinical experience, descriptive studies, and/or reports of expert committees. The literature was reviewed and evaluated for quality according to the categories outlined by the U.S. Preventive Services Task Force (1995): I. Evidence obtained from at least one properly designed randomized controlled trial. II-1. Evidence obtained from well-designed controlled trials without randomization. II-2. Evidence obtained from well-designed cohort or case-control analytic studies, preferably from more than one center or research group. II-3. Evidence obtained from multiple time series, with or without the intervention. III. The opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees. The rating of supporting literature for this document is class III. No supporting literature for genetic counseling practices in categories I and II was identified. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 124 Bennett et al. The authoring committee sought expert review from specialists in Fabry disease and genetic counseling in the United States. Opinions were sought from representatives of advocacy groups for Fabry disease. The full document was made available for review on the Internet to all Full and Associate members of the National Society of Genetic Counselors (NSGC). At the time, 78% of the 1536 NSGC Full and Associate members were registered on the NSGC listserv. The NSGC Full and Associate membership includes genetic counselors, physicians, nurses, attorneys, PhD genetics professionals, and social workers. The NSGC Ethics Subcommittee (consisting of seven genetic counselors, and an ad hoc bioethicist/clergy representative) and an attorney for the NSGC reviewed the revised document. No conflicts with the NSGC Code of Ethics were identified in the final document. The NSGC Board of Directors approved the final document in August 2001. OVERVIEW OF FABRY DISEASE Fabry disease (Online Mendelian Inheritance in Man, 2000, Catalogue #301500) is an X-linked inherited lysosomal storage disorder of glycosphingolipid catabolism resulting from deficient or absent activity of the lysosomal enzyme α-galactosidase A (α-gal A). This enzyme helps to break down and remove glycolipids (complex sugar–fat substances). The enzymatic defect leads to progressive accumulation of the glycolipid globotriaosylceramide (Gb3 or Gl3) or ceramidetrihexoside in the lysosomes in the cells of most organs. This accumulation leads to selective damage of the renal glomerular and tubular epithelial cells, the myocardial cells and valvular fibrocytes, neurons of the dorsal root ganglia and autonomic nervous system, as well as damage in the endothelial, perithelial, and smooth muscle cells of the vascular system. Progressive renal insufficiency and cardiovascular disease are causes of significant morbidity and mortality in Fabry disease, but virtually any organ may be affected (Desnick et al., 2001; MacDermot et al., 2001a,b). In the predialysis and prekidney transplant era, the average age of death in males was 41 years (Colombi et al., 1967; Wise et al., 1962). Recently, MacDermot et al. obtained median age at death in Fabry disease from cumulative survival curves in a cohort of 51 affected males and 32 obligate carrier females. Fifty percent of males with Fabry disease had died by age 50 years, and 50% of obligate carrier females died by age 70. When compared with the general population, this represents an approximate reduction of 20 years and 15 years respectively in life span (MacDermot et al., 2001a,b). Clinical Condition and Medical Management Table I provides a summary of the major medical features of Fabry disease. Although Fabry disease predominantly affects males, approximately 60–70% of carrier females show clinical expression of the disease, which is assumed to be P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 Genetic Counseling: Fabry Disease 125 Table I. Clinical Features of Fabry Disease, the Typical Age of Symptom Onset, and Summary of Medical Management (Brady and Schiffmann, 2000; Brown et al., 1997; Desnick et al., 2001;a MacDermot et al., 2001a,b;b,c Rosenberg et al., 1980; Stryker and Kreps, 2001; Sybert, 1997) Clinical features Neuropathic pain/burning in extremities Particularly the palms and soles of the feet May be constant or episodic Seen in 80%a,b of males and 70% of femalesc Ophthalmologic Corneal dystrophy and opacity (corneal verticillata) Lenticular abnormalities (Fabry cataract) Seen in 100% of males and 70–80% of females Retinal changes associated with hypertension and uremia Angiokeratoma Individual punctate angiectases, dark red to blue-black color Distribution is most dense between the umbilicus and knees, on the buttocks and penis, and in the oral mucosa and underside of the tongue Not painful and do not itch or blanch with pressure Seen in 70% of males by age 17, 30a –35%c of females (breast, back, trunk, inner thighs) Hypohidrosis (acquired) Seen in 56b –66%a of males and up to 33%c of females Cardiac disease Left ventricular enlargement (88%b of males, 19% of femalesc ) Valvular involvement (most commonly mitral insufficiency) Conduction abnormalities Later manifestations include angina pectoris, myocardial ischemia and infarction, congestive heart failure TIA or CVA (24%b of males, 22%c of females) Typical age of onset Management Onset in childhood or Analgesic medications; a early adolescence combination of drugs such as Dilantin, Carbamazepine, and/or Neurontin may be indicated to control or minimize the intensity of pain episodes Avoid situations that may trigger symptoms (e.g., exercise, fatigue, emotional stress, extreme temperature or humidity, fever) Usually Slit-lamp examination is helpful in asymptomatic, but diagnosis but the cataracts and may be detected at corneal abnormalities do not any age require treatment as they rarely impair visual acuity May also enable carrier detection when positive in females with equivocal enzyme test results Usually increase in number over time May be seen in childhood (by age 10–20 years) Argon laser therapy for cosmetic improvement Childhood Avoid extremes of heat, humidity, and physical exertion Increase water intake 20s and 30s in males; Monitor with EKG and 2-dimensional later in females and M-mode echocardiography Medications for control of hypertension, conduction abnormalities, angina (as needed) Conduction defects may necessitate the use of a pacemaker Severe cardiac disease may necessitate heart transplant (Continued ) P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 126 11:37 Style file version Nov. 19th, 1999 Bennett et al. Table I. (Continued ) Clinical features Cerebrovascular disease Thromboses Transient ischemic attacks Basilar artery ischemia Aneurysm Seizures Strokes Vascular dementia White matter changes Occurs in <1% of females Renal disease Proteinuria Hypertension Chronic renal insufficiency End stage renal failure in ∼31%b of males and 1–4%a,c of females Psychological Depression Diminished quality of life Auditory problems Hearing loss (bilateral, sensorineural). Seen in ∼41%b of males, 23%c of females. In a cohort of 23 males, 78% had abnormal audiogramsb Tinnitus (38%b of males, 23%c of females) Vertigo Gastrointestinal problems Acute intermittent abdominal pain, vomiting, cramps Diarrhea (postprandial) Seen in 33a –69%b of males, 58%c of females Male infertility Erectile dysfunction Pulmonary involvement Airway obstruction Typical age of onset Mid-30s Management Brain MRI Psychometric testing Anticoagulants may be indicated in patients at risk of stroke/aneurysm Seizure medications, as appropriate Appears most often Urinalysis between age 30 and 24-h urine collection for total protein 40 years in males and creatinine Glomerular filtration rate BUN Medications for hypertension (e.g., ACE inhibitors) Hemo- or peritoneal dialysis (as appropriate) and possible renal transplantation May become manifest Quality of Life measurement tools at any time, but Supportive counseling and usually evident in medication, as appropriate adolescence or adulthood May become manifest Audiograms at any time, but Hearing aides usually evident in adolescence or adulthood May become manifest Medication (antidiarrheals, fat at any time, but absorption supplements) usually evident in Dietary modifications (high fiber diet, adolescence or avoid fatty foods) adulthood 30s or 40s May be clinically silent, although often evident in adulthood Urological consultation and medication, as appropriate Pulmonary function testing Bronchodilators, inhalants Discontinue smoking P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 Genetic Counseling: Fabry Disease February 27, 2002 11:37 Style file version Nov. 19th, 1999 127 due to skewed X-inactivation (nonrandom lyonization). Discordance in expression of the disease in monozygotic female heterozygotes has been described (Desnick et al., 2001; Levade et al., 1991). Among males, the clinical manifestations of Fabry disease usually begin in childhood or adolescence, with recurrent severe pain in the extremities, angiokeratomas, corneal dystrophy, and episodic fevers. Fabry disease often causes renal failure, requiring renal dialysis and kidney transplant, a major cause of morbidity and mortality in this patient population. Cardiac manifestations, usually cardiomyopathy and/or premature coronary artery disease, is another leading source of morbidity and mortality for individuals with Fabry disease. Cerebrovascular accidents are common in Fabry disease. Premature death usually occurs from renal failure, or from cardiac or cerebrovascular disease. Table I provides a summary of the medical features and management of Fabry disease. Neuropathic pain is the most common and debilitating symptom of Fabry disease. Pain occurs in the form of severe acute attacks (referred to as Fabry crisis), or as a chronic background pain (e.g., aching, tingling, tenderness). Individuals with Fabry disease use terms such as burning, piercing, sharp, appalling, and agonizing to describe their pain. The pain is often present in the palms and soles of the feet (acroparesthesias), and often radiates to the arms and legs. Neuropathic abdominal pain is also common, and is often accompanied by nausea, diarrhea, and vomiting. A painful crisis can be precipitated by fever, exercise, fatigue, emotional stress, or rapid changes in the environmental temperature or humidity, or the crisis can have no precipitating cause (Desnick et al., 2001). The most common ophthalmologic findings in Fabry disease are corneal dystrophy and opacity (haziness) with a whorl-like pattern (corneal verticillata). Two types of lenticular abnormalities may be seen—a posterior opacity (the “Fabry cataract”) with a spoke-like appearance, and a granular, anterior capsular, or subcapsular wedge-shaped lipid deposit. The cataracts and corneal anomalies do not impair visual acuity. Retinal vascular changes associated with hypertension and uremia may occur, including retinal artery thrombosis resulting in blindness. The conjunctival and retinal vessels may be tortuous (a nonspecific finding), even in the absence of hypertension, with venous changes being more common than arterial lesions. Acquired hypohidrosis (decreased sweating, saliva, and tear production from autonomic nervous system dysfunction) develops in adolescence. This problem is exacerbated by extremes of heat, humidity, and physical exertion. Because Fabry disease affects multiple organ systems, a multidisciplinary team approach is useful (Peters et al., 1997). Referrals to multiple subspecialists may be necessary to achieve optimal patient care. Case management can include specialists in medical genetics, pediatrics, or internal medicine, nephrology, ophthalmology, cardiology, dermatology, neurology, pain management, organ transplant, OT/PT, social work, and psychology/psychiatry. A sample form for clinical evaluation of an individual with Fabry disease is shown in Fig. 1. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 128 Style file version Nov. 19th, 1999 Bennett et al. Intravenous enzyme replacement therapy is currently in extended clinical research trials awaiting FDA approval. Several reports demonstrate this treatment to be a promising approach to the management of the manifestations of Fabry disease (Brady and Schiffmann, 2000; Eng et al., 2001a,b; Gahl, 2001; Schiffmann et al., 2000, 2001). These studies revealed reduction in plasma and tissue globotriaosylceramide levels in the vascular endothelium of the kidney, skin, and heart as surrogate markers of clinical benefit. There are also indications of decreased pain and improvement in quality of life. Other genetic therapies are also being considered for Fabry disease, such as substrate deprivation, chaperonemediated enzyme enhancement, and gene therapy (Abe et al., 2000; Desnick, 2001). Genetic Diagnosis and Genotype/Phenotype Correlations Fabry disease is considered highly penetrant in males although variable in its expression. In affected males, the clinical diagnosis is confirmed by α-gal A deficiency. The majority of males with Fabry disease have absent or very low enzyme activity (1–2% of normal) and classical phenotype with multiple disease manifestations. Some males with clinical features of Fabry disease have residual α-gal-A enzyme activity (level of enzyme activity 1–10%) (Desnick et al., 2001). Several males were described with higher residual enzyme activity, approximately 3–10% of normal, and appeared to have milder expression of Fabry disease. These Fig. 1. Sample clinic evaluation for Fabry disease. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 Genetic Counseling: Fabry Disease 11:37 Style file version Nov. 19th, 1999 129 Fig. 1. (Continued ) individuals were diagnosed with Fabry disease later in life after cardiomyopathy of unknown etiology was discovered (Desnick et al., 2001). About 60–70% of females heterozygous for a Fabry disease mutation have some disease manifestations, and approximately 10% of these heterozygous females have severe manifestations, similar to the phenotype in males (Desnick et al., P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 130 11:37 Style file version Nov. 19th, 1999 Bennett et al. Fig. 1. (Continued ) 2001; MacDermot et al., 2001b). Enzyme activity is not reliable for determining female carrier status because women who are obligate carriers have variable levels of alpha-gal A that can overlap with enzyme levels found in healthy controls. The α-gal A locus is on Xq22.1. The gene is 12 kb in length and contains seven exons. More than 200 mutations have been identified in the α-gal A gene (Human P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 Genetic Counseling: Fabry Disease 11:37 Style file version Nov. 19th, 1999 131 Gene Mutation Database, http://archive.uwcm.ac.uk/uwcm/mg/hgmd0.html); most of the mutations are unique (“private mutations”) in each family (Ashley et al., 2001; Eng et al., 1997; Topaloglu et al., 1999). Therefore it is necessary to sequence the entire α-gal A gene and flanking regions to identify the Fabry disease mutation in a family. The limitations of gene sequencing include limited clinical availability from CLIA-approved laboratories, labor intensity, the possibility that not all mutations will be identified, and the possible identification of sequence variations of uncertain significance. Several laboratories offer enzymatic testing for Fabry disease (refer to http://biochemgen.ucsd.edu/). Currently, the availability of direct DNA sequencing for diagnostic testing in the United States is limited to a few CLIA-approved laboratories (refer to www.genetests. org). A suggested flow diagram for genetic testing for Fabry disease is shown in Fig. 2. De novo mutations have been documented, and therefore the absence of family history suggestive of Fabry disease does not rule out the diagnosis of Fabry disease (Germain et al., 2001). The rate of new mutations is unknown. In a recent survey of 67 families with Fabry disease in the United Kingdom, 20 males had no family history of the disease (MacDermot et al., 2001a). Of the 150 mutations identified by Desnick and colleagues, 71.6% of the mutations were coding region missense or nonsense mutations, 6.5% were mRNA processing defects, and 21.9% were large or small gene rearrangements (Desnick et al., 2001). Identification of a gene mutation is diagnostic but does not predict the severity of disease. Mutations in R112H, R301Q, and G328R have been described in individuals with primarily cardiac manifestations, although they also have been reported in patients with classical disease symptoms (Ashton-Prolla et al., 2000; Desnick et al., 2001). Differential Diagnosis Although the individual features of Fabry disease may not be specific, they should lead to a high index of suspicion particularly in the presence of a family history of Fabry disease. Table II lists some of the conditions to consider in the differential diagnosis of Fabry disease. Many conditions have symptoms similar to Fabry disease. Angiokeratomas are not pathognomonic of Fabry disease. Neuropathic pain (pain associated with the cranial nerves, or the peripheral or autonomic nervous system) is associated with many different acquired and inherited conditions including diabetes mellitus and trigeminal neuralgia. Some individuals with Fabry disease pain crises have been misdiagnosed with erythromelalgia. There are also multiple causes of premature cardiovascular disease and cardiomyopathy. Kanzaki disease is a rare autosomal recessive condition caused by deficiency of α-N -acetylgalactosaminidase (α-NAGA). The disease manifestations begin in puberty with clinical findings of angiokeratoma corporis diffusum, peripheral P1: GDX Journal of Genetic Counseling [jgc] 132 ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 Bennett et al. Journal of Genetic Counseling [jgc] ph105-jogc-368836 Genetic Counseling: Fabry Disease February 27, 2002 11:37 Fig. 2. Suggested diagnostic testing flow-chart—Fabry disease. All of the five testing pathways include obtaining medical history, family history, performing a physical examination, and genetic counseling prior to and following testing. -gal A = -galactosidase A; = suggested pathway; ⊕ eye examination = ophthalmologic finding consistent with Fabry disease; ª eye examination = normal ophthalmologic examination. P1: GDX Style file version Nov. 19th, 1999 133 P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 134 Style file version Nov. 19th, 1999 Bennett et al. Table II. Conditions to Consider in the Differential Diagnosis of Fabry Disease (Desnick et al., 2001; Dinc et al., 2000; Kodoma et al., 2001; Sybert, 1997) Symptom Angiokeratoma Hypohidrosis Numbness/tingling/pain Condition Fucosidosis Aspartylglucosaminuria GM1 gangliosidosis GM2 gangliosidosis Sialidosis Galactosialidosis Late infantile gangliosidosis Beta-mannosidosis Kanzaki disease Petechiae Angiokeratoma of Fordyce Angiokeratoma of Mibelli Angiokeratoma circumscripta Hypohidrotic ectodermal dysplasias Kanzaki disease Familial Mediterranean fever Acute intermittent porphyria Multiple sclerosis (especially in females) Rheumatic fever Erythromelalgia (erythermalgia) Arthritis, rheumatoid and juvenile Raynaud’s syndrome Neuropathy Corneal dystrophy Proteinuria, lipiduria, and lamellar inclusions in the lysosomes of glomerular epithelial cells Phenocopy from long-term chloroquine or amiodarone therapy Phenocopy from silica dust Inheritance AR AR AR AR AR AR AR AR AR Multiple causes Acquired Acquired Acquired Several, AD AR AR AD Multifactorial Multifactorial ?AD, or secondary erythromelalgia due to thrombocythemia Multifactorial Multifactorial Many acquired and genetic causes, with diabetes mellitus being one of the most common Drug induced Environmental Note. AR: autosomal recessive; AD: autosomal dominant. sensory neuropathy, hearing loss, Meniere syndrome, and cardiac hypertrophy. (This is the same enzyme deficiency found in Schindler disease, but the primary disease manifestation in Schindler disease is severe central nervous system involvement evidenced in the first year of life.) Interestingly, the α-NAGA gene and the α-gal A gene in Fabry disease have greater than 50% homology, and are thought to have evolved from the same gene (Kodoma et al., 2001). P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 Genetic Counseling: Fabry Disease 135 Incidence The incidence of Fabry disease is estimated to be 1:117,000 live births in Caucasian males (Meikle et al., 1999). Fabry disease has been identified in all racial groups, and there is no known racial or ethnic predilection. Fabry disease was diagnosed (by measuring α-gal A activity) in 3% of unselected male patients with left ventricular hypertrophy (Nakao et al., 1995), and 9% of patients with a diagnosis of nonobstructive hypertrophic cardiomyopathy (Kuhn et al., 1982). PRIMARY GENETIC COUNSELING CONSIDERATIONS: FABRY DISEASE Assessment Ascertain the client’s primary questions and concerns and mutually develop a plan to address these concerns. Medical Family History A. Using standardized pedigree symbols, obtain at least a three generation pedigree from the consultand or proband (Bennett, 1999; Bennett et al., 1995). i. Targeted medical family history questions are included in Table III. ii. Because Fabry disease is inherited in an X-linked pattern, special attention should be paid to the medical history of maternal relatives of a male proband (i.e., his mother’s siblings and their children, both of her parents and their siblings and children, and the mother’s maternal and paternal grandparents). Family history of maternal relatives of a female proband is also important, as is the history of her father and his relatives. iii. Note any consanguinity, documenting the exact relationship of unions between relatives on the pedigree (i.e., consanguinity could put female relatives at risk for being homozygotes). B. Verify positive family history with medical records, if possible. Document results of enzyme analysis and/or DNA mutation analysis. C. For female carriers, obtain pregnancy history (gravidity, parity, termination of pregnancy, spontaneous abortion), and potential exposure to possible teratogenic agents (see under Teratogenesis). D. Maintain family history with respect to the confidentiality of the consultand/proband and extended family members. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 136 Bennett et al. Table III. Suggestions for Targeted Family History Questions for Fabry Disease Answer the following questions about yourself, or any of your blood relatives (note the age that the problem or event occurred) Has anyone had an eye exam (called a slit-lamp examination) to look for the nonharmful eye findings that can be seen in Fabry disease? Does anyone have any unusual skin findings (such as a rash or birthmark)? If so, describe them and their location on the body. Does anyone have problems with sweating (not sweating enough), or problems with tolerating extremely hot or cold temperatures? Does anyone have major gastrointestinal problems such as chronic diarrhea, vomiting, or recurrent abdominal pain? Has anyone experienced problems with hearing loss or ringing in the ears? Do you or your relatives have a history of heart disease? Specifically, has anyone been told they have heart murmurs or problems with their heart valve(s)? Does anyone have a history of chest pain (angina)? Has anyone died of heart disease? Does anyone have a history of irregular heart rhythm? A pacemaker? Has anyone received a heart transplant? Is there a history of high blood pressure (hypertension)? Does anyone have a history of kidney problems? Is anyone on dialysis? Has anyone had a kidney transplant? Has anyone had a stroke, particularly at a young age? Does anyone have problems with memory or thinking? Have you or your relatives had a seizure? If so, how many? Do they take medications for this? Has anyone had a history of chronic high fevers? Do you or your relatives have a problem with chronic pain? Do you or your relatives experience burning sensations in the palms of the hands or the soles of the feet? If so, what has been done to treat this? Do you or your relatives have a history of feeling tired all the time or experiencing weakness? Have you (if male) or the men in your family experienced infertility (problems having children) and/or erectile dysfunction? Has anyone in the family been treated for depression? Is there a history of suicide or suicide attempts in the family? For female patients who are pregnant or planning a pregnancy What medications are you taking? Psychosocial History of the Consultand/Proband Attempt to build a relationship with the consultand/proband by validating, empathizing, and listening. Assess, record, and address the consultand’s/proband’s A. Level of comprehension and communication. B. Level of education, employment, and social functioning, as appropriate. C. History of depression (e.g., disturbance in sleep pattern, anxiety, changes in appetite, weight gain or weight loss, fatigue, feelings of hopelessness, loss of libido, suicidal ideation). D. History of alcohol or other drug use (especially a history of using alcohol or other drugs to self-medicate for depression and/or pain control). E. Perceived burden of Fabry disease. F. Perceived notions of Fabry disease occurrence/recurrence risks. G. Coping skills. H. Family and community support systems. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 Genetic Counseling: Fabry Disease 11:37 Style file version Nov. 19th, 1999 137 Risk Assessment A. Analyze the pedigree. Using principles of X-linked recessive inheritance, provide genetic risk assessment for carrier status and the chance of having affected offspring. i. All daughters of an affected male are obligate gene carriers, whereas none of the affected male’s sons will have Fabry disease. If there is consanguinity, females are also potentially at risk for homozygosity. ii. Sons of female carriers have a 50% risk of inheriting Fabry disease, and daughters of female carriers have a 50% risk of being carriers. iii. Females can have manifestations of Fabry disease because of skewed X-inactivation. B. Offer genetic testing for family members, as appropriate (Fig. 2). i. Offer DNA mutation analysis for diagnostic or carrier testing if the mutation is known in affected family member(s). ii. Offer enzyme analysis for at-risk males. iii. Offer ophthalmologic evaluation, enzyme and DNA mutation analysis for potential carrier females. Psychosocial Issues A. The rate of depression, alcoholism, marital problems, unemployment, and suicide is high among men with Fabry disease (Abreo et al., 1984; Grewal, 1993). In a cohort of 46 men with Fabry disease, MacDermot et al. (2001b) found that only 57% were currently employed and 17% had never had a job because of the diagnosis of Fabry disease. B. Assess/identify family, peer, and community resources for appropriate services and/or support, and consider referrals as needed. C. Assess support services and accommodations in settings for school and/or employment, particularly because rapid changes in environmental temperature and humidity, physical exertion, emotional stress, and fatigue can exacerbate painful crises (Desnick et al., 2001). D. Address psychological issues related to genetic diagnosis such as denial, anxiety, anger, grief, survivor and parental guilt, blame, depression, isolation, inability to cope, hopelessness, damage to self-esteem, changed relationship with family of origin, and change in sense of identity, as indicated (Baker et al., 1998; Weil, 2000; Williams et al., 2000). E. For an individual affected with Fabry disease, explore the client’s notions of sexuality. The angiokeratomas may be a significant source of embarrassment and psychological stress. A patient in a study at the National Institute of Health summarized his distress by stating, “I have angiokeratomas on my genitalia. When you are planning to lose your P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 138 11:37 Style file version Nov. 19th, 1999 Bennett et al. F. G. H. I. J. K. virginity, the last thing you want is something that looks like a venereal disease” (Stryker and Kreps, 2001). MacDermot et al. (2001a) also found a significant proportion of individuals with angiokeratomas feared initiating sexual relationships. Chronic pain and fatigue may also contribute to sexual difficulties (Stryker and Kreps, 2001). Assess patient’s and family’s preconceived notion of affected or carrier status. Family members may have an incorrect understanding of the inheritance, and therefore they may not be aware of their chances to have a child with Fabry disease (Sørensen and Hasholt, 1983). An individual with diagnostic results that are opposite of his or her preconceived affected status may be at higher risk for adverse psychological consequences (Resta, 2000). For individuals/couples at risk to have a child with Fabry disease, assess their feelings about childbearing, prenatal diagnosis, and subsequent options (e.g., pregnancy termination or continuation upon diagnosis of an affected male fetus, feelings about termination of pregnancy given potential treatment options). Assess self-concept as it relates to threatened parental role (McConkie-Rosell and DeVellis, 2000). Individuals diagnosed with Fabry disease may have seen many health care professionals before receiving a confirmative diagnosis. The average time to diagnosis is 10 years, with affected individuals typically seeing 10 specialists before diagnosis (Morgan and d’A Crawford, 1988). There may be an inherent distrust of health professionals because of this experience. Address psychological issues arising from the uncertainty of the variable clinical phenotype. Individuals with a tentative diagnosis of Fabry disease who are subsequently found to not have this condition may have mixed feelings on receipt of a normal (negative) genetic test result (Williams et al., 2000). For example, siblings of individuals diagnosed with Fabry disease may have always thought they would develop the condition, and they may take some time to absorb the information that they are unaffected. The “sick role” may have been unconsciously “assigned” to the family member (preselection) thereby creating the illusion of control over the randomness of gene transmission (Resta, 2000). Unaffected siblings may also experience survivor guilt. Make referrals for further psychological counseling as necessary. PRENATAL DIAGNOSIS Prenatal diagnosis for determining fetal sex is the first step in prenatal diagnosis for Fabry disease. The inability to predict clinical outcome in carrier females, P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Genetic Counseling: Fabry Disease Style file version Nov. 19th, 1999 139 many of whom remain asymptomatic, complicates prenatal counseling and diagnosis. Because of this, prenatal diagnosis for female fetuses is usually not available from the laboratories offering testing. For male fetuses at-risk for Fabry disease, subsequent enzyme analysis, or DNA mutation analysis (if the mutation has been identified in the family) can be performed on chorionic villi (CVS) or cultured amniocytes. If the family mutation is known, preimplantation diagnosis is feasible. EDUCATION/HEALTH PROMOTION A. Discuss the clinical manifestations of Fabry disease in males, and the possibility that females can be affected. B. Discuss follow-up recommendations (e.g., identification and testing of at-risk family members, scheduling follow-up visits). C. Discuss the genetics of Fabry disease and the approach to testing. i. Review X-linked inheritance and recurrence risks. ii. Review reproductive options and testing (e.g., adoption, donor egg or donor sperm, prenatal diagnosis). Include ethical concerns raised by such options, if appropriate. iii. Review costs of genetic testing, and test limitations (e.g., enzyme assay can be normal in carrier females; the percentage of residual α-gal-A enzyme activity does not correlate with clinical severity; and DNA testing may fail to identify a mutation). iv. Answer questions regarding molecular genetic aspects of Fabry disease. D. Be able to answer general questions relating to potential therapy for Fabry disease, including published trials of enzyme replacement (see under Clinical Condition and Medical Management) (Brady and Schiffmann, 2000; Eng et al., 2001a,b; Gahl, 2001; Schiffmann et al., 2000, 2001). E. Be prepared to make appropriate referrals for medical evaluations and further discussions that are beyond the scope of genetic counseling practice (Fig. 1). F. Provide contact information for support groups, as requested (Table V). FOLLOW-UP A. Arrange/facilitate additional appointments to complete the family history and genetic risk assessment, and arrangements to follow the medical progress of the patient, as indicated. B. Devise a plan for disclosing test results. C. Offer posttesting support counseling (by office visit or telephone). D. Facilitate referrals to appropriate professionals, as indicated (Fig. 1). P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 140 Style file version Nov. 19th, 1999 Bennett et al. E. Consider making available to the patient a letter to summarize major topics discussed in the genetic counseling session(s), and to facilitate informing their family members of their genetic risks (Baker et al., 1999; Hallowel and Murton, 1998). ETHICAL ISSUES AND SPECIAL CONSIDERATIONS Testing Healthy At-Risk Minors The age at which to test healthy at-risk minors is controversial, particularly if no therapy or intervention is available, or if it is unknown at what age an intervention should begin for the greatest health benefit for the child. Several position papers (ASHG/ACMG Reports, 1995; NSGC, 1995) and printed discourses (Clarke, 1998; Clarke and Flinter, 1996; Davis, 1997; Michie, 1996; Wertz et al., 1994) raise multiple concerns about potential emotional damage to the child, as well as possible discrimination. Some of the considerations of testing healthy at-risk children for Fabry disease are summarized in Table IV. Studies documenting the effect of genetic testing of children at risk for Fabry disease have not been published. Testing of seemingly healthy minors for genetic conditions is usually discouraged, unless testing allows for a health benefit due to medical intervention. Testing for Fabry disease in seemingly healthy at-risk males who are minors may be justified, given the subtle early manifestations of Fabry disease and the high likelihood of disease progression. Early diagnosis allows for closer medical monitoring and the opportunity for early intervention, especially Table IV. Pros and Cons of Asymptomatic Testing for a Minor at Risk for Fabry Disease Potential adverse consequences of testing (focus on positive test results) Damage to the minor’s self-esteem Distortion of the family’s perception of the child. Siblings may be treated differently depending on genetic status Loss of future adult autonomy and confidentiality for the tested child Adverse effects on the child’s capacity to form future relationships Fear of rejection in forming long-term relationships. Fear/guilt if person wants biological children Discrimination (insurance, employment, education, choice of mate) Increased medical surveillance for “healthy” child (especially for females). Child feels labeled Potential benefits of testing Resolution of the parent’s (and possibly the child’s) concerns about carrier status Allow child and family time to adjust to status if test is positive. No anticipation of developing disease if result is negative Anticipatory guidance such as in choosing physical activities and occupation for possibly affected child Health status is normalized and Fabry disease becomes part of that child’s sense of self Ability to make informed reproductive decisions Decreased premiums for insurance because risk factor eliminated if test result is negative Available at earliest opportunity for medical intervention including enzyme replacement therapy (when available) P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 11:37 Style file version Nov. 19th, 1999 Genetic Counseling: Fabry Disease 141 with the prospect of enzyme replacement therapy. Testing healthy at-risk minor females may be more controversial because many female carriers of Fabry disease will never have symptoms. It may be appropriate to time genetic testing for Fabry disease before an adolescent (male or female) becomes sexually active, to assist with discussions of reproductive risks and options. Testing Siblings Before Kidney Transplant Before considering a healthy sibling of a person with Fabry disease as an organ donor for the affected male, unaffected status should be confirmed by enzyme analysis or DNA testing. Enzyme analysis or DNA testing should not be initiated solely to secure a matched donor. Female carrier siblings should not be used as organ donors. Teratogenesis A careful medication history should be taken for a symptomatic woman who is planning a pregnancy or who is pregnant to determine if any medications she is taking are teratogenic. Dilantin and carbamazepine are commonly used for pain symptoms; their potential teratogenic effects should be reviewed with the client (Holmes et al., 2001). The patient can be referred to a regional teratogen service for comprehensive information. Listings of such services can be found through the Organization of Teratogen Information Services or OTIS (http://ctispregnancy.org/home.html). Confirming Parentage All daughters of affected males with Fabry disease are obligate heterozygotes. Because of possible misattributed paternity, carrier status should not be assumed. Confirmation with enzyme analysis or with DNA testing if the mutation is known is indicated to provide accurate genetic risk assessment and genetic counseling. Enzyme analysis in females may not be definitive, and DNA testing is preferred for diagnostic confirmation; ophthalmologic evaluation may also be useful in establishing carrier status for females (see under Genetic Diagnosis and Genotype/Phenotype Correlations and Fig. 2). PATIENT RESOURCES Table V contains a list of patient advocacy groups for Fabry disease. P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 142 11:37 Style file version Nov. 19th, 1999 Bennett et al. Table V. Advocacy Groups for Individuals and Their Families With Fabry Disease Resource Canadian Organization for Rare Disorders (CORD) Fabry’s Disease Support Group Fabry’s Support Group, Inc. Fabry Support & Information Group Lysosomal Diseases, Australia Lysosomal Diseases, New Zealand Morbus Fabry NORD—National Organization for Rare Disorders Address P. O. Box 814, Coaldale, Alberta T1M 1M7, Canada 10 Broadmeadow Road, Wyke Regis, Weymouth, Dorset DT4 9BS, England P. O. Box 174, The Basin 3154, Melbourne, Victoria, Australia P. O. Box 510, Concordia, MO 64020, USA Dept. of Clinical Pathology, Women’s & Children’s Hospital, 72 King Road, North Adelaide, South Australia 5006, Australia 1248 High Street, Lower Hutt City 6009, New Zealand Bergstrasse 34, Ransbach—Baumbach 56235 P. O. Box 8923, New Fairfield, CT 06812-8923, USA Phone, Fax, Web site Phone: (403) 345-4544 Fax: (403) 345-3948 http://www.cord.ca Phone: 03 9762 3910 Fax: 03 9761 3503 Phone: (660) 463-1355 Fax: (660) 463-1356 http://www.fabry.org http://www.lda.org.au http://www.ldnz.org .nz Phone: +49 2623-2710 Fax: +49 2623-9230 79 Phone: (203) 746-6518 Fax: (203) 746-6481 http://www.rarediseases.org DISCLAIMER Genetic counseling recommendations of the NSGC are meant to assist practitioners in making decisions about appropriate management of genetic concerns. Each practice recommendation focuses on a clinical or practice issue, and is based on a review and analysis of the professional literature. The information and recommendations reflect scientific and clinical knowledge current as of the publication date, and are subject to change as advances in diagnostic techniques, treatments, and psychosocial understanding emerge. In addition, variations in practice, taking into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant alternative approaches, treatments, or procedures to the recommendations outlined in this document. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does use of such P1: GDX Journal of Genetic Counseling [jgc] ph105-jogc-368836 February 27, 2002 Genetic Counseling: Fabry Disease 11:37 Style file version Nov. 19th, 1999 143 recommendations guarantee a particular outcome. Genetic counseling recommendations are not intended to supersede a health care provider’s best medical judgment. The listing of patient and professional resources does not necessarily imply NSGC endorsement. SUMMARY Without treatment, there is significant morbidity and mortality associated with Fabry disease. Given the potential benefits of early medical and psychological interventions for Fabry disease, genetic counselors need to have increased awareness about genetic testing, evaluation, and management for Fabry disease. Specific genetic counseling issues in Fabry disease include phenotype and genotype variability; genetic testing of at-risk siblings before investigation for organ donation; coping with a chronic and painful illness; increased rates of depression, alcoholism, marital/relationship difficulties, unemployment, and suicide; anxiety regarding sexual relationships because of angiokeratomas; mistrust of health professionals because of years of misdiagnosis; psychological consequences related to uncertainty because of disease variability; issues related to presymptomatic testing; issues of “preselection” especially for individuals who are not affected in a family; and consideration of occupational therapy and anticipatory counseling in view of the disease’s natural history. Ethical issues include testing healthy atrisk minors; prenatal diagnosis for a potentially treatable condition; and issues of misattributed paternity. Genetic counselors play a critical role in not only identifying individuals and at-risk relatives with Fabry disease, but in providing genetic testing services and counseling. Through on-going education and support, genetic counselors encourage families to enroll in Fabry disease registries, Quality of Life studies, and clinical trials so that more can be learned about the clinical manifestations of Fabry disease, appropriate modes of evaluation and therapy, and strategies for psychological support of these families. ACKNOWLEDGMENTS The authors are grateful to the many reviewers of the NSGC for their helpful comments, particularly members of the Genetic Services Committee and the Ethics Subcommittee. This work was initiated by the Fabry International Research Exchange (FIRE) sponsored by Transkaryotic Therapies. 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