Approximately 1 in 1000 young children has a major hearing impairment (threshold >80dB).  Significant hearing loss also occurs in about 1 in 25 people under age 45, and in 1 in 10 by age 60 (threshold >25dB). Most of the hearing loss is genetic with over 30 autosomal recessive (70-80%), dominant (23-30%) and X-linked (2-3%) forms. A large proportion (60-75%) of nonsyndromic hearing loss in children has been localized to defects in a single gene, Connexin 26 (Cx26) on chromosome 13q11-12.

Recently a second gene locus, Connexin 30 (Cx30), has been identified that can also cause recessive hearing loss, although at a lower incidence than Cx26. Connexin 30 is located very close to Cx26 on chromosome 13 and is co-expressed as a prerequisite for proper development of the cochlea. The most important finding is that hearing loss can be a result of a compound heterozygote, with a single mutation in each gene. Consequently, affected patients in which only a single Cx26 mutation, is detected should also undergo testing for the Cx30 mutation. Both tests may be ordered together in a Connexin Hearing Loss Panel, or may be further combined with testing for mitochondrial hearing loss in a Nonsyndromic Hearing Loss Panel for the most efficient and economical diagnosis available.

• To identify a second mutation in children that carry a single CX26 mutation.
• To determine whether a hearing defect in a child is hereditary.
• To determine the genetic basis for hearing loss in an affected individual, in order to modify therapy.
• To evaluate the risk of having a child with hearing loss.

• Individuals at risk who wish prenatal diagnosis.

• This test is often included with testing for Connexin 26.

• Detection of a 342kb deletion involving the Cx30 gene.

• Blood EDTA (purple top) tubes:  

            Newborn: minimum 1-2 mL          

            Child/Adult: prefer 2 tubes of 3-5 mL

• Prenatal testing: Please contact the laboratory for instructions.

TURNAROUND TIME:     8 working days

CPT CODES: