Genetics of sensorineural hearing loss
-
60% genetic; 40% environmental -
350 different conditions
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genetic cases are divided into SYNDROMIC or NONSYNDROMIC categories
- proportions of genetic cases:
- nonsyndromic autosomal recessive (DFNB) -56%
- syndromic (Alport, Usher, Jervell & Lange-Nielsen, Pendred, Branchio-oto-renal, Waardenberg, Stickler, Treacher Collins) - 30%
- nonsyndromic autosomal dominant (DFNA) - 12%
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mitochondrial - 2%
- human genes that are mutated encode for a wide variety of proteins
- connexins (gap junction proteins; esp. Cx26 which is only expressed in cochlea)
- tight junctions
- developmental regulators or transcription factors
- ion transporter proteins
- potassium channel proteins
- myosins (MYO7A is also only in the cochlea)
- tectorial membrane
- cytoskeleton, cadherin-like, transmembrane serine proteases, vesicle formation
- unknown