COCH
The Clinical
Diagnostics Service of
the Molecular Otolaryngology Research Laboratory is a Joint
Commission-approved CLIA-accredited diagnostic laboratory that
offers mutation screening of several genes.
DFNA9 (OMIM#: #
601369)
Mutations in the cochlin gene COCH are
responsible for autosomal dominant nonsyndromic sensorineural
hearing loss at the DNFA9 locus. This gene maps to chromosome
14q12-q13. Persons with hearing loss caused by a mutation in COCH can
have vestibular symptoms such as vertigo or vestibular
hypofunction as assessed by electronystagmography. For this
reason, some investigators have described COCH-related
hearing loss as being Ménière’s-like.
Ménière’s Disease (OMIM#: #156000)
Symptoms of Ménière’s disease include hearing
loss, vertigo, tinnitus and aural fullness.
COCH (OMIM#: *603196)
COCH is
a major component of the extracellular matrix of the inner ear.
The gene has 12 exons that encode a 550-amino acid protein. At
least nine different mutations in COCH have
been identified in families segregating autosomal dominant
nonsyndromic hearing loss with a range of clinical vestibular
involvement.
MORL screening methodology
Screening for COCH is
performed via DHPLC and sequencing. Oligonucleotide primers
have been designed to amplify each exon. Amplified samples are
run on the DHPLC; abnormal elution profiles are sequenced to
identify specific mutations. Exons carrying known SNPs are
directly sequenced
Sensitivity
Sensitivity is greater than 99%.
Turn-around time
Turn around time is approximately 3 months.
Cost: $500
Indications for screening
This test is appropriate for any patient with
autosomal dominant hearing loss at the DFNA9 locus or persons
with a Ménière’s-like phenotype.
GeneTests GeneReviews – Deafness and
Hereditary Hearing Loss
References
Morrison, A.W. et al.: Genetics
(molecular biology) and Ménière’s disease. Otolaryngol Clin
North Am. 35(3): 497-516, 2002.
PubMed ID: 12486836
PubMed Search
Fransen,E. et al: High
prevalence of symptoms of Ménière’s disease of three families
with a mutation in the COCH gene. Hum
Mol Genet. Aug. 8(8):1425-9, 1999
PubMed ID: 1040098
PubMed Search
Verstreken, M. et al: Hereditary
otovestibular dysfunction and Ménière’s
disease in a large Belgian family is caused by a missense
mutation in the COCH gene. Otol
Neurotol. Nov. 22(6):874-81, 2001.
PubMed ID: 11698812
PubMed Search
Usami, S. et al.: Mutations
in the COCH gene are a frequent cause of autosomal dominant
progressive cochleo-vestibular dysfunction, but not of Ménière’s
disease. Eur J
Hum Genet. Oct.,11(10):744-8, 2003
PubMed ID: 14512963
PubMed Search
Sanchez, E. et al.: Absence
of COCH mutations in patients with Ménière’s disease. Eur
J Hum Genet. Jan.,12(1):75-8, 2004.
PubMed ID: 14704763
