MUTATION IN BRIEF
HUMAN MUTATION Mutation in Brief #504 (2002) Online
© 2002 WILEY-LISS, INC.
Received 22 September 2001; revised manuscript accepted 21 February 2002.
GJB2 Mutations in Iranians With Autosomal
Recessive Non-syndromic Sensorineural Hearing Loss
Hossein Najmabadi1, Robert A Cucci2, Solmaz Sahebjam1, Nafiseh Kouchakian1, Mohammad
Farhadi3, Kimia Kahrizi1, Sanaz Arzhangi1, Naiimeh Daneshmandan1, Khalil Javan1, and
Richard JH Smith2
1Genetic Research Center, Welfare Science & Rehabilitation University, Tehran, Iran; 2 Molecular
Otolaryngology Research Laboratories, Department of Otolaryngology Head and Neck Surgery, University of
Iowa; Iowa, IA United States; 3 Department of Otolaryngology, Rasoul Akram Hospital, Iran University of
Medical Sciences, Tehran, Iran.
*Correspondence to: Dr. Hossein Najmabadi, Welfare & Rehabilitation University, Kodakyar St., Beheshti Ave.,
Evin, Tehran, Iran 19834; Tel.: 98212050174; Fax: 98212407814; E-mail: Hnajm@mavara.com
Contract grant sponsors: Iran Deputy of Research and Technology, Ministry of Health & Medical Education;
Contract grant number: P6193; Contract grant sponsor: National Institutes of Health; Contract grant number: R01-
Communicated by Mark H. Paalman
Hereditary hearing loss (HHL) is an extremely common disorder. About 70% of HHL is
non-syndromic, with autosomal recessive forms accounting for ~ 85% of the genetic load.
Although very heterogeneous, the most common cause of HHL in many different world
populations is mutations of GJB2, a gene that encodes the gap junction protein connexin 26
(Cx26). This study investigates the contribution of GJB2 to the autosomal recessive non-
syndromic deafness (ARNSD) load in the Iranian population. One hundred sixty eight
persons from 83 families were studied. GJB2-related deafness was diagnosed in 9 families (4,
35delG homozygotes; 3, 35delG compound heterozygotes; 1, W24X homozygote; 1, non-
35delG compound heterozygote). The carrier frequency of the 35delG allele in this
population was ~1% (1/83). Because the relative frequency of Cx26 mutations is much less
than in the other populations, it is possible that mutations in other genes play a major role in
ARNSD in Iran. © 2002Wiley-Liss, Inc.
KEY WORDS: Autosomal recessive non-syndromic deafness, ARNSD; hereditary hearing loss; HHL; Connexin 26; Cx26;
Genetic hearing impairment is one of the most prevalent inherited sensory disorders, affecting approximately
1/2000 live births (Nance et al., 1997). Autosomal recessive non-syndromic sensorineural deafness (ARNSD) is
the most common form of severe inherited hearing loss (Reardon, 1992). It is an extremely heterogeneous disorder
with at least 30 reported loci (Van Camp et al., 1997; Zbar et al., 1998; Keats and Berlin, 1999, Van Camp and
Smith, 2001; http://www.uia.ac.be/dnalab/hhh).
Serendipitously, mutations in one gene, GJB2 (MIM# 121011), have been shown to be the major cause of