Download GENETICS AND HEARING LOSS

GENETICS AND HEARING LOSS
Submitted by Kathleen Corbin, M.A., CCC-A, Audiologist
for the
ISHA Fall Conference, September 21, 2013
Over one in every 500 infants has or will develop a hearing loss in early childhood
GENETIC HEARING LOSS – approx. 50% to 60% of all with hearing loss
MODE OF TRANSMISSION
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80% Recessive
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15% Dominant
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2% x-linked
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2% Mitochondrial
CATEGORIES OF GENETIC HEARING LOSS
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Non-Syndromic (70%)
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Syndromic (30%)
NON-SYNDROMIC
Common mutation sites
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GJB2 (Gap Junction Protein, Beta 2) gene (Causal factor of 40% of non-syndromic hearing
loss) –
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Myosin VI
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TECTA
GENETICS and HEARING LOSS
K. Corbin, p. 2
SYNDROMIC DEAFNESS
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More than 600 different syndromes identified
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Auditory Profile
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Conductive, sensor neural or mixed
Unilateral or bilateral
Symmetrical or asymmetrical
Progressive or stable
COEXISTENT DEFICITS
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Cardiovascular
Renal
Neurologic
Pulmonary
Ophthalmic
Orthopedic
Endocrine
Immunologic
SYNDROMIC HEARING LOSS
INHERITED VIA RECESSIVE TRANSMISSION
USHER SYNDROME
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Most common eye/ear disorder
Estimated 10% of all children with SNHL
Hearing loss
 Type I: Absent vestibular function
 Severe to Profound SNHL
 Type II: Moderate to Severe SNHL
 Type III: Progressive SNHL
Retinitis Pigmentosa
PENDRED SYNDROME
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Estimated at 5% of all children with hearing loss
Profound sensor neural hearing loss (cochlear)
Vestibular Dysfunction
Thyroid defect, goiter
GENETICS and HEARING LOSS
K. Corbin, p.3
JERVELL and LANGE-NIELSON SYNDROME
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Profound SNHL
Cardiac abnormality
Recurrent drop attacks
Sudden death
INHERITED VIA DOMINENT TRANSMISSION
WAARDENBURG SYNDROME
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Estimates of 2.3% of all children with hearing loss
Type I appearance of widened nasal bridge -20% with SNHL;
Type II no appearance of widened nasal bridge - 50% with hearing loss
Pigmentary abnormalities
White forelock
Partial albinism
Early graying
TREACHER COLLINS
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Conductive hearing loss
Craniofacial anomalies
Eyelid colobomas
STICKLER SYNDROME
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More prevalent in the Midwest region of the United States
Hearing loss due to Eustachian tube dysfunction secondary to palatal anomalies;
SNHL which may be progressive or conductive anomalies have been noted
Flattening of the facial profile
Cleft palate
Myopia/retinal detachment/cataracts
Neuropathy
BRANCHIO-OTO-RENAL SYNDROME (BOR)
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Estimated in 2% of all children with profound SNHL
Hearing loss is present in 75% of patient with BOR
CHL (30%)
SNHL (20%)
Mixed (50%)
Malformation of the pinnate and preauricular pits
Renal anomalies are markedly varied and may be asymptom
GENETICS and HEARING LOSS
K. Corbin, p.4
NEUROFIBROMATOSIS II
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Vestibular schwannomas with secondary hearing loss and other intracranial tumors
45% - 50% have accompanying hearing loss
75% have unilateral hearing loss
Hearing loss is neural or central
INHERITED VIA X-LINKED TRANSMISSION
Alport Syndrome
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Incidence estimated at 1% of all children with hearing loss
Progressive SNHL (High-frequency; Cochlear)
Progressive Nephritis
Lens Abnormalities
Renal and Hearing impairment usually manifest in adolescence or early adult years
INHERITED VIA MITOCHONDRIAL DISORDERS
Kearns-Sayre syndrome
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Incidence unknown
Neuromuscular disease
SNHL
NON-GENETIC HEARING LOSS (30%)
Maternal Influences
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Infection – viral or bacterial
Substance abuse
Environmental exposure
Birth Complication
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Respiratory distress/perinatal asphyxia
Hyperbilirubinemia
Hemorrhage perinatal or intraventricular
COMBINATION OF GENES AND ENVIRONMENT (10%)
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Ototoxicity-Induced SNHL from Aminoglycoside Exposure
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Noise-Induced SNHL from Excessive Noise Exposure