Particular distribution of the GJB2/GJB6 gene mutations in Mexican population with hearing impairment.
BACKGROUND
Hereditary sensorineural hearing loss (SNHL) is a genetically heterogeneous disorder worldwide. Mutations in the GJB2 gene are a frequent cause of hereditary SNHL. There is a prevalence of certain mutations in various populations which suggests that specific mutations may be influenced by ethnic background.


OBJECTIVE
To analyze the prevalence of GJB2, GJB6 mutations in several geographic areas of Mexico in patients with hereditary SNHL.


METHODS
One hundred and forty Mexican unrelated propositi with prelingual SNHL were included in the study. All patients had three previous generations born in Mexico and belonged to no specific ethnic group. Analyses of the GJB2 and GJB6 genes and mt.1555A<G were performed in all subjects.


RESULTS
Twenty-three homozygous mutations, 57 heterozygous mutations, 1 double heterozygous (GJB2/GJB6) and 59 wild-type genotypes in the GJB2 gene were observed. Three patients had the homozygous c.del35 mutation whereas 26 patients were heterozygous for this gene defect. Only one patient with the GJB6 gene deletion was present (it includes the double heterozygous GJB2/GJB6). The mt.1555A>G mutation was not detected.


CONCLUSIONS
We found a great variety of mutations depending on the analyzed region in patients with SNHL; 57.86% of patients had affection in one or two alleles in GJB2 or GJB6 genes whereas 42.14% were wild-type. In some cases, allele distribution depended on region. Molecular studies of more genes involved in hereditary non-syndromic SNHL are required to completely confirm the molecular basis of hearing loss in Mexican population.
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
Francisco
F
Loeza-Becerra
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
María del Refugio
Mdel R
Rivera-Vega
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
Mirna
M
Martínez-Saucedo
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
Luz María
LM
Gonzalez-Huerta
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
Héctor
H
Urueta-Cuellar
Servicio de Audiología, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico.
Pedro
P
Berrruecos-Villalobos
Servicio de Genética, Hospital General de México, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico. Electronic address: sercuevas@yahoo.com.
Sergio
S
Cuevas-Covarrubias
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008800:Mexico; D009154:Mutation; D017422:Sequence Analysis, DNA; D055815:Young Adult
D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26
Connexins; GJB2 gene; GJB6 gene; Gene mutations; Hypoacusia