Genetics Flashcards
Hearing Loss–Hidden disability
Most frequently occurring birth defect, people don’t realize they have a HL
NICU: higher chance of having HL 2.5/100
HL Statistics
3/1000 kids born with bilateral HL
1/1000 will have 40dB or greater mild
2/1000 will have 30dB or greater
2.5-3/1000 if include unilateral
by 9 years, stats double
33 infants born every day in US with HL
Risk Factor
Only 50% kids have HL associated with risk factor, 270 genes identified as being associated with HL
Incidence per 10,000 of congenital defects/diseases
- HL @ 30
- Cleft lip/plate @ 12
- Down syndrome @ 11
2-3/1000 babies born with HL due to…
50% genetic (30% is syndromic)
25% idiopathic
25% environmental (anoxia, exposed to drugs)
Syndromic Hearing Loss
Progressive HL:
Alport, NF2, Usher Type 3
Other:
BOR
congenital”
Apert, CHARGE, Jervell & Lange Nielsen, Pendred, Usher types I & 2, Waardenburg
Alport Syndrome
Progressive SNHL, occuar issues, bilateral mild-severe HL can progress, affects males more
NF2: Neurofibrotosis 2
slowly progresive HL, vestibular schwanomas benin tumors that cause this progressive HL–when remove tumors hearing is lost entirely and tumors come back
Usher Type 3
Progressive HL, progressive loss of vision (night vision lose peripheral vision then eventually tunnel vision)
Branchio-oto-renal (BOR)
any kind of HL (conductive, mixed, SNHL), kids born with outer ear malformations, mild profound kidney problems–over 90% of kids with this disease have hearing problems—-ear and kidney are first 2 pharyngeal arches
Apert Syndrome
Born with HL, skeletal malformations (prominent foreheads, suken eyes), very small body, many born with spina bifida, varying degrees of cognitive impairment (typically conductive HL) more common with older parents
CHARGE
colobomma of the eye (hole in iris), heart defects, coanal atresia (narrowing of nasal passage), renal problems, genitalia, ears (HL)
can lead to blindness, heart defects result in death, dialysis, debate in cochlear implant for older kids–only if parents have realistic expectations and get cardiologist to sign off
Jervell & Lange Nielsen Syndrome
not long life, fainting episodes due to heart disorders, profound SNHL
Pendred Syndrome
SNHL, vestibular dysfunction, thyroid problems
Usher Types 1&2
Profound SNHL at birth, progressive loss of vision
Waardenburg
Significant HL, wide set eyes & flattened, 2 different colored eyes, white lock of hair, cognitively intact—more physical in nature
Nonsyndromic Hearing Loss
Pendred Syndrome/DFNB4
Mitochondrial
Auditory Neuropathy (AN)
Connexin
DFNB4
Enlarged vestibular aqueduct, connects cochlea and vestibular portion–RED FLAG for progressive HL
more of a sudden SNHL cochlea HL then next time hearing drops a little lower and doesn’t come back to normal, fall off bike and now deaf because impact results in wipeout of cochlea—cannot play contact sports, stereoids help for a time
Mitochondrial HL
finding it in small group of people in Arab-israeli (mother passes on to ALL children)
Auditory Neuropathy/AN
genetic or environmental
classic symptoms: kid with normal OAEs, good HC good), leading cause we think is somewhere HC are functioning how they should but somewhere between release of NT and pickup of NT at the nerve there is a disconnect
true neuropathy means there is a problem in nerve-misnomer
normal cochlear function, abnormal neural function–any kind of hearing loss–spectrum
Key to diagnose Auditory Neuropathy
Normal OAEs, Poor ability to understand speech, abnormal ABR
Connexin 26
Common non-syndromic HL–ton of genetic work going into this–anywhere from mild-profound HL
in some ethnic populations 80% of HL due to this, in general population only 20% of HL—need to get a genetic workup to see if this is cause
Acquired
Condition develops later in life
Carrier
Unaffected individual who has one normal gene and one mutant/recessive gene
