Download Slide 1

Document related concepts

Ploidy wikipedia , lookup

Nutriepigenomics wikipedia , lookup

Medical genetics wikipedia , lookup

Polycomb Group Proteins and Cancer wikipedia , lookup

Meiosis wikipedia , lookup

Genome (book) wikipedia , lookup

Chromosome wikipedia , lookup

Skewed X-inactivation wikipedia , lookup

Down syndrome wikipedia , lookup

NEDD9 wikipedia , lookup

Y chromosome wikipedia , lookup

Polyploid wikipedia , lookup

Neocentromere wikipedia , lookup

Karyotype wikipedia , lookup

X-inactivation wikipedia , lookup

Transcript
Klinefelter Syndrome
KRISTIN CLEMENS PGY 5
ENDOCRINE ROUNDS
JANUARY 30, 2013
Case
 20 year old male
 Presents to new family doctor for physical
 No known medical conditions
 Inguinal hernia repair
 No medications, no significant family history
 Puberty at age 13, tall compared peers
 Development seemed to slow
 Learning disability, behavioural problems
 Didn’t finish high school
 Living at home
Physical Exam
 Tall, long legs, BMI 30 kg/m2
 Normal cardiac, respiratory and abdominal exams
 Scant facial and chest hair
 Bilaterally small testicles – 4mL
 Klinefelter syndrome?
Objectives
 To learn about the origin of Klinefelter syndrome
and understand it’s genetics
 To review its many clinical manifestations and
associated medical co morbidities
 To learn how to optimally manage patients with the
condition
Klinefelter Syndrome
 Most common sex chromosome aneuploidy seen in
clinical practice
 1 in 500 live male births
 Increased maternal age
 ?Association with paternal age
 First described by Klinefelter in 1942
 Reports of 9 men with gynecomastia, sparse facial
and body hair, small testes and an inability to
produce sperm
Genetics
 Extra X chromosome first documented in 1959
 Classically 47 XXY – 89%
 48 XXXY among other variants
 Non-disjunction – abnormal partitioning of
chromosomes
Non-disjunction:
Meiosis
 Abnormal partitioning of chromosomes during
meiosis such that the resultant haploid gametes have
too many or too few chromosomes
Meiosis
Meiotic non-disjunction
Meiosis I
Meiosis II
genetics.thetech.org
 53% result from 1st paternal meiotic non disjunction
 34% from 1st maternal meiotic non disjunction
 9% 2nd meiotic division
Non disjunction:
Mitosis
 Mosaic 47 XXY
 Mitotic non disjunction within the zygote
 10% of cases
 Variable phenotype
 Typically less severe
 Depends on the specific tissues in which an extra X
chromosome is present
 If normal karyotype in the testis may have intact
spermatogenesis and fertility
Pathogenesis:
Extra X Chromosome(s)
 Genes of X chromosome play an important role in
the sex development in males and females at the
level of the gonad
 More than 100 X chromosome genes are expressed
in the testes
 Genes on extra X chromosome:
 Testicular failure - progressive loss of germ cells,
seminiferous tubule hyalinization and fibrosis
 Low testosterone
 Progressive hypogonadism
Furthermore…
 Androgen receptor gene on X chromosome
 Variable CAG repeats on exon 1
 Length of the highly polymorphic CAG repeat
inversely related to AR activity
 Short lengths more stable with more marked effect of
androgens
 Longer lengths less stable- androgen insensitivity
 In Klinefelter’s, at least 2 X chromosomes
 Shortest CAG repeat is preferentially inactivated –
non-random X chromosome inactivation
 Less effective androgen receptor
 Further contributes to the phenotype
Clinical Manifestations
Infancy and Childhood
 Micropenis
 Small testes
 Normal surge of testosterone over 1-6 months
 Early gonadal dysfunction and decreased fetal
testosterone in utero
 Hypospadias
 Cryptochordism
 Hypotonia
 Cleft palate
 Inguinal hernia
 Hypertelorism
 Elbow dysplasia
 Clinodactyly
 High arched palate
Journal of Pediatrics
 Delayed developmental progress
 Delayed gross and fine motor skills
 Adjustment disorders
 Deficits in language and executive function
 Dyslexia
 ADHD
 Emotional difficulties
 Pre-puberty may see disproportionate lower
component compared with upper
 Tall stature for familial size
 Unfused growth plates secondary to androgen
deficiency
 Narrow shoulders, broad hips
Puberty
 Normal onset of puberty with rise in testosterone,




LH, FSH until about 13 to 14 years or Tanner stage 3
puberty
Slow progression or arrest of pubertal changes
Impaired Leydig cell reserve and low testosterone
levels
Testicles fail to increase in size and become firm due
to a progressive loss of germ cells and seminiferous
tubule hyalinization and fibrosis
Incomplete virilization with AR instability
Gynecomastia
Gynecomastia
 15% of estrogen secreted by testes as estradiol or
estrone
 Rest from peripheral conversion from testosterone



95% from the testicles
Adipose tissue has P450 aromatase activity important for
transforming androstenedione into estrone
Conversion increases with age and obesity
Science Direct
Breast tissue development
 Balance between estrogen and testosterone
 Estrogen stimulates the growth and differentiation of
breast epithelium
 Androgens inhibit the growth and development of
breast tissue
Why gynecomastia in Klinefelter’s?
 High circulating LH levels stimulate aromatase
activity in Leydig cells leading to higher levels of
estradiol relative to testosterone
 Low testosterone
 Alteration in estrogen to androgen ratio from high
estrogen or low androgen concentrations
 Breast tissue enlargement
Adulthood
 Signs/symptoms of hypogonadism
 Infertility
 Gonadal failure and loss of germ cells from tubule
hyalinization and fibrosis of seminiferous tubules
There’s more!
Osteoporosis
 Decreased bone mass in 20-50% of patients and
osteoporosis in up to 15%
 Low testosterone?
 Testosterone aromatized to estrogen which decreases
bone resorption
 Also effects osteoblasts directly through the
androgen receptor
 Promotes periosteal bone formation and reduces
bone resorption through adult life
 Need testosterone to achieve peak bone mass
 Ferlin et al 2011
 Cross-sectional cohort study
 112 treatment naïve KS XXY and 50 aged matched
controls
 43% of KS patients had low bone mass
 No significant relationship between testosterone,
bone markers (calcium, phosphate, albumin, PTH,
25 hydroxyvitamin D) and bone mass
 CAG repeats not different in those with normal and
low bone mass
 Likely multifactorial
 Other contributors may include abnormal androgen
receptor, X chromosome inactivation, increase fat
mass and reduced muscle mass, low vitamin D levels
 Low insulin like factor 3 levels produced by Leydig
cells
Lung pathology
 Bronchitis
 Bronchiectasis
 Unknown pathophysiology
Malignancies
 Germ cell tumours
 Mediastinal tumours in 8% (50x expected rate)
 Relative risk of 67 in cancer registries
 Need to consider in those with known Klinefelter’s and
precocious puberty
 Non-Hodgkins lymphoma
 Acute leukemia
Breast cancer
 20 fold increase in breast cancer
 Denmark cohort of 832 KS found that 3.7 to 7.5%
had BC
 Brinton et al studied 4.5 million men in US Veterans
Affairs and noted 3518 cases of male breast cancer
with 642 in Klinefelters
 RR 16.83 (6.81-41.62)
 Alteration in endogenous hormone ratios, genetic
predisposition, presence of gynecomastia
Autoimmune conditions
 SLE
 RA
Cardiovascular anomalies
 Mitral valve prolapse
 Aortic valvular disease
 Berry aneurysms
 Varicose vein
 Ulcers
 Danish registry
 Thromobophlebitis and venous thrombosis HR 5.29
(3.29-8.5)
 PE HR 3.6 (1.92-6.74)
 CAD HR 1.71 (1.28-2.29)
 Abnormalities in plasminogen 1, clotting factors,
obesity
Endocrine
 Graves disease
 Thyroiditis
 Dyslipidemia
 DMII
DMII
 Jiang-Feng et al
 Retrospective longitudinal study of 39 men with
Klinefelter’s and 40 with idiopathic
hypogonadotropic hypogonadism
 Prevalence of diabetes in KS group was 20.5% and in
the IHH group 5%
 Testosterone effect on insulin sensitivity
 IM testosterone (approximately 4 years) to keep total
levels <10 nmol/L
 ?Testosterone effect doesn’t explain whole story
 Extra copy of X chromosome leads to decreased
insulin sensitivity or insulin resistance
 Autoimmune disease?
 Metabolic syndrome, increased weight
 Increased truncal fat and waist measurements
during childhood, adolescence and adulthood
Variable presentation
 Genetics – the more X chromosomes, the more
severe
 CAG length
CAG lengths
 Those with short CAG
repeat lengths found to
have more stable
relationships, higher
educational levels,
greater responses to
testosterone treatment
 If long CAG and reduced
AR activity, have longer
arms and legs, smaller
testes, lower BMD,
greater degree of
gynecomastia
Diagnosis
 Important as under-diagnosed condition
 Only 10% diagnosed prior to puberty
Under diagnosed
 Variable phenotype
 Limited awareness of condition
 Reduced physical observations in teens
Diagnosis
 Can be informed of the diagnosis by prenatal
screening usually for the detection of Down
syndrome
 Karyotype or FISH for an extra X chromosome
 Cultured peripheral blood lymphocytes, skin
fibroblasts, testicular tissue if mosaicism is suspected
Other supportive tests
 See Barr body (X inactivation)
 Subject to false positives and negatives
 In adolescence/adulthood
 Increased FSH/LH in 80-90%
 Hypergonadotropic hypogonadism
 Elevated estrogen to testosterone ratio
 Low testosterone in 50-75%
 May be normal if have increased SHBG
Inhibin B and AMH
 Low inhibin B and anti-mullerian hormone
 Both Sertoli cell products
 Inhibin B is produced the the Sertoli cell in response
to FSH stimulation
 Markers of testicular function, may reflect loss of
Sertoli cells
Patient management
 Multidisciplinary
 Increased mortality and morbidity because of
concomitant diseases
Gynecomastia
 Consideration of breast reduction surgery
 ?Testosterone therapy may lead to regression
 Little data on the benefit of aromatase inhibitors and
anti-estrogens on reversal of breast enlargement
Learning Disabilities, Developmental Delay
 Social work
 Psychology
 Speech and behavioural therapy
 Physical and occupational therapy
Hypogonadism
 Testosterone
 Topical for infants with micropenis
Testosterone therapy
 When LH and FSH start to rise and low testosterone
documented
 Goal of increasing linear growth, secondary sex
characteristics, muscle mass BMD, libido, energy,
body composition
 Goal to normalize LH and keep testosterone in
normal range
 Life long therapy
Adulthood?
 Nielson 1988
 Adult KS patients treated with testosterone for 3
years – treatment naive
 77% had subjective benefit from therapy
 Improved mood, irritability, energy and drive, better
sleep and relationships with others
Bone Health
Other
 Annual breast exam
 CXR/CT
 Echocardiogram
Fertility
 Germ cells are depleted at an accelerated rate after
puberty
 Maturation arrest of spermatogenesis, clumping of
Leydig cells
 Early diagnosis important
 Van Saen et al
 7 patients with 47 XXY
 Followed testosterone, FSH, inhibin B, spermaturia
 Testicular biopsy when no increase in testicular
volume, increased FSH or decreased inhibin
 6/7 with extensive fibrosis and hyalinization
 Spermatogonia in seminiferous tubules with normal
architecture in the youngest men with normal FSH
and inhibin B
 Limited experience in banking as <10% diagnosed
prior to puberty
Testicular sperm extraction and ICSI
TSE and ICSI
 TSE permits identification of the relatively few
seminiferous tubules that contain active
spermatogenesis and harvesting of sperm from the
small testes of men with Klinefelter’s for use in ICSI
 More than 60 cases of success worldwide
 Reported pregnancy rates of 50%
 Risk of sex chromosome aneuploidy
 Genetic counseling
Guidelines?
Take home messages
 Most common sex chromosome aneuploidy
 Be aware of the diagnosis – patients with KS will
present to different physicians at different ages and
for different reasons
 Look for associated conditions
 Used team based, multi-disciplinary management
References
 Bojesen et al. Klinefelter’s syndrome, DMII and the metabolic syndrome.









Molecular Human Reproduction 2010; 16: 396-401.
Bojesen et al. Klinefelter syndrome. Nature Clinical Practice 2007; 4: 192203.
Endo EXPO Meet the Professor Handbook
Ferlin et al. Bone mass in patients with Klinefelter’s syndrome: role of
testosterone levels and androgen receptor gene CAG polymorphism
Ferlin et al. Osteoporosis in Klinefelter’s syndrome. Molecular Human
Reproduction 2010; 16: 402-410.
Groth et al. Klinefelter’s syndrome: an update. JCEM 2013; 98: 20-30
Jiang-Feng et al. Prevalence and risk factors of diabetes in patients with
Klinefelter’s syndrome. Fertility and Sterility 2012; 98: 1331-1335.
Sokol et al. It’s not all about the testes: medical issues in patients with
Klinefelter’s syndrome. Fertility and Sterility 2012; 98: 261-265
Van Saen et al. Can pubertal boys with Klinefelter’s benefit from sperm
banking? Human Reproduction 2012; 27: 322-330.
Williams Textbook of Endocrinology
Thank you!