Non-Syndromic Hearing Loss

​​Approximately 70% of all genetic hearing losses caused by genetic mutations are non-syndromic (hearing loss that occurs without any other symptoms). This type of hearing loss occurs by itself and can be classified by the following patterns of inheritance.

Autosomal Recessive

Connexin 26 (CX26) on the GJB2 (or DFNB1) ​gene is responsible for the most common non-syndromic recessive genetic hearing loss and may account for up to 50% of recessive hearing loss in children. Although there is no consistent hearing loss pattern, roughly 50-80% of those affected have severe to profound hearing loss. There are many other autosomal recessive non-syndromic hearing loss genes.

Characteristics of CX26 Hearing Loss

  • Degree of hearing loss may vary among siblings
  • Progressive in 30%
  • Both ears (bilateral) and no structural changes
  • Sometimes a change in CX26 is paired with a missing gene, Connexin 30 (CX30 or GJB6) to cause hearing loss

More information about Connexin 26

Autosomal Dominant

Several genes (DFNA) are known to cause dominant non-syndromic hearing loss. Age of onset, rate of progression, and degree of DFNA-related hearing loss vary even among family members.​

X-Linked (Sex-Linked)

Several genes (DFNX) are responsible for this type of hearing loss. The type and degree of hearing loss varies depending on the gene affected.

Mitochondrial

1555DELG: a type of sensorineural hearing loss that may be progressive and may lead to sudden hearing loss when exposed to aminoglycoside antibiotics (e.g., neomycin, gentamycin, streptomycin, kanamycin, tobramycin, or amikacin).