Table 6c.

Select Common Causes of X-Linked Syndromic Hearing Loss

Gene(s)SyndromeHearing LossComment
COL4A5 Alport syndrome 1SNHLTypically after age 10 yrsVarying severity, progressive
TIMM8A Deafness-dystonia-optic neuronopathy syndrome (Mohr-Tranebjaerg syndrome)SNHLEarly childhoodProgressive, pre- or postlingualNonsyndromic HL mimic: HL is always presenting manifestation. Slowly progressive dystonia or ataxia develops in teens, & slowly progressive decreased visual acuity from optic atrophy develops at age ~20 yrs. Dementia develops at age ~40 yrs.

SNHL = sensorineural hearing loss


Three modes of inheritance are recognized for Alport syndrome: X-linked (COL4A5; 85% of Alport syndrome), autosomal recessive (COL4A3 and COL4A4), and autosomal dominant (COL4A3). Rarely, Alport syndrome is associated with digenic inheritance.

From: Genetic Hearing Loss Overview

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