Genetics of congenital deafness in the Palestinian population: multiple connexin 26 alleles with shared origins in the Middle East.
In some Palestinian communities, the prevalence of inherited prelingual deafness is among the highest in the world. As an initial step towards understanding the genetic causes of hearing loss in the Palestinian population, 48 independently ascertained probands with non-syndromic hearing loss were evaluated for mutations in the connexin 26 gene. Of the 48 deaf probands, 11 (23%) were homozygous or compound heterozygous for mutations in GJB2. Five different mutations were identified: ivs1(+1) G-->A, 35delG, 167delT, T229C, 235delC. Nine deaf probands were homozygous and only two compound heterozygous. Among 400 hearing Palestinian controls, one carrier was observed (for 167delT). We show that GJB2 ivs1(+1) G-->A disrupts splicing, yielding no detectable message. Linkage disequilibrium analysis suggests, in the Palestinian and Israeli populations, a common origin of the 35delG mutation, which is worldwide, and of 167delT, which appears specific to Israeli Ashkenazi and Palestinian populations. A high prevalence of deafness, high frequency of homozygosity rather than compound heterozygosity among deaf, and low mutation carrier frequency together reflect the high levels of consanguinity of many extended Palestinian families. Some of the 25 families with multiple cases of inherited prelingual deafness and wildtype GJB2 sequences may represent as-yet-unknown genes for inherited hearing loss.
Shahin
Hashem
H
Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978 Israel.
Walsh
Tom
T
Sobe
Tama
T
Lynch
Eric
E
King
Mary-Claire
MC
Avraham
Karen B
KB
Kanaan
Moien
M
D000483:Alleles; D018912:Arabs / Q000235:genetics*; D001483:Base Sequence; D016022:Case-Control Studies; D002648:Child; D002874:Chromosome Mapping; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003241:Consanguinity; D004247:DNA / Q000235:genetics; D004252:DNA Mutational Analysis; D003638:Deafness / Q000151:congenital* / Q000235:genetics*; D005260:Female; D006239:Haplotypes; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008877:Middle East; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree
D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26; D004247:DNA