QUESTIONS AND ANSWERS
congenital - ✔✔present at birth
hereditary - ✔✔subgroup of congenital. genes transmitted from parent to child
-known genetic cause
familial - ✔✔subgroup of congenital and hereditary.
refers to feature that is seen in multiple members of a family, but not necessarily linked
to one specific gene.
-unknown precise, genetic etiology
-ex. diabetes, cancers, hypertension
genetic - ✔✔subgroup of congenital
-mutation in a gene
-may or may not be hereditary
acquired - ✔✔happens with no genetic component
-ex. melanoma
congenital hearing loss - ✔✔-1-3 in 1,000 births (only 50% accounted for by genetics)
-70% is non-syndromic (most of the genes are recessive 80%)
Where in genes are hearing losses found? - ✔✔majority on autosomes (not sex-linked)
~20% on x-chromosome linked
how many syndromes are associated with hearing loss? - ✔✔over 500 known
-over 120 known genes for hearing loss
four mutations to detect deafness at birth - ✔✔-connexin mutations - one of leading
causes of deafness (GJB2 and GJB6 genes)
-mtDNA A1555G mutation - increased aminoglycoside induced deafness
-SLC26A4 mutations - Pendred syndrome, EVA
-Citomegalovirus (CMV) - not disorder but tested at birth
GJB2 - ✔✔Gap Junction Beta 2 protein
-identified 1997
-Connexin 26: allows ion transfer between cells
-most common cause of SNHL
-12-24% of permanent HL in kids
,DFNB4 - ✔✔-mutation in SLC26A4 gene
-autosomal recessive
-bilateral, severe to profound SNHL
-EVA or mondini malformations
mitochondrial hearing loss - ✔✔-very rare
-mutations in MTRNR1 and MTTS1
-maternal inheritance
-highly variable onset
-variable hearing loss
Crouzon Syndrome - ✔✔-premature fusion of skull bones
-bulging eyes and strabismus (eyes angled either inward or outward)
-typically show normal intelligence
-autosomal dominant (genetic mutation that is not necessarily hereditary)
Findings and Interventions for Crouzon Syndrome - ✔✔-conductive HL in 55%
-accompanied by atresia or stenosis
-can have absent TM, malleus and stapes fixation, narrow middle ears (OAEs probable
absent)
-use BC if can't use air conduction
-BAHA, preferential seating, FM system, IEP
Pfeiffer Syndrome - ✔✔-premature fusion of skull resulting in "clover-leaf" pattern
-webbed or angled fingers/toes
-low set ears
-may have cognitive problems/developmental delay
-autosomal dominant (FGFR 1,2,3)
Findings and Interventions for Pfeiffer Syndrome - ✔✔-most often a CHL, but could
have MHL
-SDT/SAT if not SRT
-ABR
-VRA audiometry
prevalence of Pfeiffer syndrome - ✔✔1 in 100,000 births
can pinna placement be a telling sign of crania-facial disorders? - ✔✔Yes!
Pierre Robin Sequence - ✔✔-cleft soft palate
-small jaw
-tongue falls back in throat
-difficulty breathing
-recurrent ear infections
-low set ears
, -works with SLPs and surgeons along with audiologists
-CHL
treacher collins syndrome - ✔✔-underdeveloped bones of head and face
-abnormalities of external and middle ear (atresia, stenosis, microtia)
-it's a new mutation in the person (TCOF1 gene that is responsible for bone and tissue
formation)
-CHL
prevalence of treacher collins syndrome - ✔✔1 in 10,000 to 50,000 births
apert syndrome - ✔✔-premature closure of skull sutures
-similar to crouzon syndrome but has large range of severity
-unique symptom: webbing on fingers and toes
-recurrent ear infections
-autosomal dominant: can be new mutation
-about 70% have reduced intelligence, while others have normal intelligence
-CHL
prevalence of apert syndrome - ✔✔1 in 200,000 live births
Alport syndrome (renal disorder) - ✔✔-progressive loss of kidney function
(sodium/potassium recycling problem)
-80% are x-linked (milder in females)
-different chains of type IV. collagen
-SNHL: onset in childhood or early adolescence
-visual defects
red flag symptom of aport syndrome - ✔✔microscopic hematuria: blood in urine that is
only found in lab.
prevalence of alport syndrome - ✔✔1 in 50,000 live births
Jervell and Lange-Nielsen syndrome - ✔✔-Congenital long QT syndrome
-Autosomal recessive, SNHL (severe to profound)
-mutations in KCNQ1 or KCNE1 genes
-cardiac conduction defects (fainting, drop attacks and sudden death) (half untreated
will die before age 15)
prevalence of Jervell and Lange-Nielsen Syndrome - ✔✔1 to 6 in 1 million people
worldwide
Pendred Syndrome - ✔✔-autosomal recessive
-one of most common syndromes with HL
-mutated gene responsible for pendrin protein generation (SLC6A4 mutation)