Hearing Loss

Question 1

What is conductive hearing loss?

Answer 1

Sounds cannot get through the outer and middle ear

Caused by blockage of your ear canal, a hole in your ear drum, problems with three small bones in your ear, or fluid in the space between your ear drum and cochlea

Question 2

What is sensorineural hearing loss?

Answer 2

Happens after inner ear damage.

Problems with the nerve pathways from your inner ear to your brain can also cause SNHL

Damage to the hair cells within the inner ear, the vestibulocochlear nerve, or the brain’s central processing centers.

Question 3

What is the frequency of prelingual hearing loss?

Answer 3

1/500

Question 4

What percentage of prelingual hearing loss is acquired/environmental?

Answer 4

20%

Question 5

What percentage of prelingual hearing loss is genetic?

Answer 5

80%

Question 6

What percentage of prelingual genetic hearing loss is nonsyndromic?

Answer 6

80%

Question 7

What percentage of genetic hearing loss is AR?

Answer 7

80%

Question 8

What is the phenotype of most AD nonsyndromic hearing loss?

Answer 8

Onset variable, postlingual, progressive

Question 9

What is the phenotype of Waardenburg syndrome?

Answer 9

Variable SNHL
Pigmentary abnormalities

Genes: PAX3, MITF, EDNRB, EDN3, SOX10

Question 10

What are the characteristics of Branchiootorenal disorder spectrum (BOR)?

Answer 10

conductive, sensorineural, or mixed hearing loss
branchial cleft abnormalities (i.e. preauricular pits)
malformations of external ear
renal anomalies

Question 11

What are the characteristics of Stickler syndrome?

Answer 11

progressive sensorineural and/or conductive hearing loss
cleft palate
spondyloepiphyseal dysplasia
precocious arthritis
high incidence of retinal detachment due to severe myopia

Question 12

What is the phenotype of Usher syndrome?

Answer 12

SNHL and retinitis pigmentosa

-Type I - congenital severe-to profound SNHL, abnormal vestibular dysfunction

-Type II - congenital mild-to-severe SNHL (mild to moderate in the low frequencies and severe to profound in the higher frequencies), and normal vestibular function

-Type III - progressive HL - deterioration of vestibular function

Question 13

What is the phenotype of Pendred syndrome?

Answer 13

Congenital SNHL (severe-to profound)
Thyroid goiter, develops in puberty or adulthood

Question 14

What is the phenotype of Jervell and Lange-Nielsen
syndrome?

Answer 14

Congenital profound SNHL
Long QT syndrome - syncopal episodes and may have sudden death

Question 15

What is the phenotype of Biotinidase deficiency?

Answer 15

Some degree of SNHL
Cutaneous features (skin rash, alopecia)
hypotonia
seizures
developmental delay

Question 16

What is the phenotype of Refsum disease?

Answer 16

early retinitis pigmentosa
anosmia (loss of sense of smell)
caused by faulty phytanic acid metabolism
Severe progressive SNHL
ataxia
ichthyosis

Question 17

What is the phenotype of Mucopolysaccharidosis type II (Hunter syndrome)?

Answer 17

• At birth, individuals are Typical

At ~2 years:
-Vocal cords also enlarge causing a deep, hoarse voice
-large head (macrocephaly) and a buildup of fluid in the brain (hydrocephalus)
- develop hearing loss and recurrent ear infections
- develop heart valve problems that cause the heart to become enlarged and heart failure.
- grow steadily until about age 5, and then growth slows, short stature
- developmental and speech delay with regression

Question 18

What is the phenotype of Alport syndrome (X-linked)?

Answer 18

varying severity progressive SNHL (usually after age 10)
progressive glomerulonephritis (progressing to renal failure)
various ophthalmologic problems.

Question 19

What is the phenotype of Mohr-Tranebjaerg syndrome
(deafness-dystonia-optic atrophy syndrome)?

Answer 19

SNHL hearing loss (pre and post-lingual)
impaired vision
dystonia or ataxia in teens
fractures,
intellectual disability.

Question 20

What are some Chromosomal disorders that have hearing loss?

Answer 20

-22q11.2
- 16p12.2 microdeletion
- Trisomy 21
- 45, X
- 47, XXY
- 1p deletion
- 4p deletion
- 17p11.2 (Smith-Magenis Syndrome)

Question 21

What is the phenotype of MELAS
(mitochondrial encephalomyopathy, lactic acidosis,
and stroke-like episodes)?

Answer 21

• m.3243 A>G (MTTL1) - 2%-6% of individuals with
  diabetes mellitus in Japan; 61% of persons with DM
  and this pathogenic variant have hearing loss.
• Sensorineural
• Also implicated in MELAS – tissue, heteroplasmy, penetrance