Hereditary Hearing Loss

Question 1

What testing is done as part of Newborn Hearing Screening?

Answer 1

ABR (auditory brainstem response) or OAE (otoacoustic emissions)
Follow-up is needed to confirm HL after positive screen (typically via diagnostic ABR)

Question 2

Picture of the inner, middle, and outer ear. Just need to know about the inner, middle, outer ear, cochlea.

Answer 2

Question 3

What type of hearing loss is due to abnormality of the inner ear (cochlea)?

Answer 3

sensorineural

Question 4

What type of hearing loss is due to abnormality of the external and/or middle ear?

Answer 4

conductive

Question 5

Is it possible for hearing loss to be due to a combination of sensorineural and conductive issues?

Answer 5

Yes, this is called mixed.

Question 6

What is the most common environmental cause of prelingual hearing loss?

Answer 6

Congenital CMV (cytomegalovirus)

Question 7

What prenatal infections other than CMV can contribute to hearing loss?

Answer 7

toxoplasmosis, rubella, herpes

Question 8

What is an example of a postnatal infection that can contribute to hearing loss?

Answer 8

bacterial meningitis

Question 9

What is the first thought we should have when considering cases of hearing loss?

Answer 9

genetic vs infection

Question 10

Is Stickler Syndrome associated with hearing loss?

Answer 10

Yes
sticky wicket -

Question 11

Is Treacher Collins syndrome associated with hearing loss?

Answer 11

Yes
Preacher Collins can’t hear!

Question 12

What are the key features of Waardenburg?
Is it autosomal dominant or recessive?
What genes are involved?

Answer 12

• congenital sensorineural hearing loss
• white forelock, hair hypopigmentation
• pigmentation abnormality of the iris
• dystopia canthorum (less of the whites of the eyes can be seen b/c there is more skin covering) only for type I
• mostly an autosomal dominant condition
• type I: PAX3 (AD)
• type II: MITF (AD), SOX10 (AD), SNAI2 (AD)
• types III & IV are less common and can be AD or AR

Question 13

What are the key features of Brachiootorenal Spectrum Disorder (BOR)?
What is the level of penetrance?
What is the level of expressivity?
Whcih genes are involved?
What is the inheritance pattern?

Answer 13

• hearing loss (conductive, sensorineural, or mixed)
• branchial cleft cyst aka cleft sinus, a branchial cleft cyst is a lump that develops in the neck or just below the collarbone. Branchial cleft cysts form during development of the embryo. They occur when tissues in the neck and collarbone area (branchial cleft) fail to develop normally
• microtia (small ears)
• Preauricular pits/tags (small hole or skin tag in front of ear
• renal agensis/hypoplasia/dysplasia (kindeys don’t form normally)
• 100% penetrance but variable expressivity
• EYA1 (40%)
• genetics unknown (50%) - rely on clinical diagnosis
• Autosomal Dominant**

don’t get too hung up on medical nomenclature

Question 14

What are some key features of Usher Syndrome?
What is the inheritance pattern?
What genes are involved and what is spcific about their phenotype?

Answer 14

• retinitis pigmentosa
• hearing loss (often sensorineural)
• delayed walking
• accounts for 50% of the deaf/blind population
• Autosomal Recessive
• large number of causative genes, the most common are:
• type I (40%): MYO7A - earlier onsent vision loss
• type II (57%): USH2A - later onset vision loss (about teenage years)
• of note: USH is a common gene name for Ushers

BLIND/DEAF
AR
MYO7A
USH