Abstract
BackgroundWe studied the molecular basis of NSHL in Republic of Altai (South Siberia, Russia). The Altaians are the indigenous Asian population of the Altai Mountain region considered as a melting-pot and a dispersion center for world-wide human expansions in the past.MethodsA total of 76 patients of Altaian, Russian or mixed ethnicity and 130 Altaian controls were analyzed by PCR-DHPLC and sequencing in the GJB2 gene. The GJB6 deletion and the common non-syndromic deafness-causing mitochondrial mutations were also tested when appropriate.Results8.3% of the Altaian chromosomes were carrying GJB2 mutations versus 46.9% of the Russian chromosomes. The 235delC mutation was predominant among Altaians, whereas the 35delG mutation was most prevalent among Russian patients.ConclusionWe found an Asian-specific GJB2 diversity among Altaians, and different GJB2 contribution for deafness in the Altaian and Russian patients. The high carrier frequency of 235delC in Altaians (4.6%) is probably defined by gene drift/founder effect in a particular group. The question whether the Altai region could be one of founder sources for the 235delC mutation widespread in Asia is open.
Highlights
We studied the molecular basis of Non-syndromic hearing loss (NSHL) in Republic of Altai (South Siberia, Russia)
We report here the results of a study based on patients presenting mainly prelingual deafness, with the mutation analysis of the GJB2 gene, the screening of the GJB6D13S1830 deletion, and the study of five mitochondrial mutations involved in NSHI
GJB2 gene GJB2 mutations were detected in 23.7% of the patients (18 out of 76) (Table 1)
Summary
The Altaians are the indigenous Asian population of the Altai Mountain region considered as a melting-pot and a dispersion center for world-wide human expansions in the past. Mutations in the GJB2 gene, encoding the connexin 26 gap-junction protein, account for a significant proportion of NSHL [2]. The substantial contribution of several nuclear genes [3,4] and the pathogenic mitochondrial mutations in NSHL was established in some populations [5,6]. The high frequencies of the 35delG mutation in the Caucasians, the 167delT in Ashkenazi Jews, and the 235delC mutation among east Asian populations have been shown to be the results of founder effects [8,9,10,11,12].
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