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ENT · Genetic hearing loss: connexin 26
Sample itemWhich gene mutation is the commonest cause of non-syndromic autosomal recessive congenital sensorineural hearing loss?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. GJB2 (connexin 26)
Mutations in GJB2, encoding connexin 26, cause the most frequent non-syndromic congenital sensorineural loss. Connexin 26 forms gap junctions that recycle potassium in the cochlea. SLC26A4 is linked to Pendred syndrome and COL4A5 to Alport syndrome.
Option by option
A. SLC26A4
SLC26A4 mutation causes Pendred syndrome.
B. MYO7A
MYO7A mutation causes Usher syndrome type 1B.
C. COL4A5
COL4A5 mutation causes X-linked Alport syndrome.
D. GJB2 (connexin 26) (correct)
Correct. GJB2 is the commonest gene.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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