Occurrence of del(GIB6-D13S1830) mutation in Italian non-syndromic hearing loss patients carrying a single GJB2 mutated allele.
Molecular screening for GJB2 (connexin 26) mutations represents the standard diagnostic approach for the genotype definition of non-syndromic deafness. Nevertheless, a single GJB2 pathogenic mutation is detectable in a relevant number of cases, therefore failing to explain the phenotype. We aimed at assessing the occurrence of the recently described del(GIB6-D13S1830) mutation, occurring in the connexin 30 gene, in a group of Italian hearing-impaired patients carrying a single GJB2 mutated allele. A total of 59 non-syndromic hearing loss (NSHL) patients were screened for GJB2 mutations. Among these, nine NSHL patients were found to be heterozygous for a single GJB2 mutation. These patients, heterozygotes for different GJB2 mutated alleles (35delG, L90P, M34T, V153I), together with 11 additional 35delG/neg cases previously described, were studied for the presence of the del(GIB6-D13S1830) mutation. Two double heterozygotes del(GIB6-D13S1830)/35delG were identified. In both cases the degree of hearing loss was profound. Furthermore, GJB2 molecular screening led to the identification of a novel change (T55G) occurring in compound heterozygosity with the V37I mutation. In conclusion, our data suggest a significant frequency of del(GIB6-D13S1830) mutation in Italian hearing-impaired subjects (10% of unexplained GJB2 heterozygotes) similar to that reported in other European countries.
Gualandi
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E
Dipartimento di Medicina Sperimentale e Diagnostica, Sezione di Genetica Medica, Università di Ferrara, Italy. gdf@dns.unife.it
Ravani
A
A
Berto
A
A
Burdo
S
S
Trevisi
P
P
Ferlini
A
A
Martini
A
A
Calzolari
E
E
D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D005820:Genetic Testing; D034381:Hearing Loss / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007558:Italy; D019656:Loss of Heterozygosity; D020125:Mutation, Missense; D010641:Phenotype
D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26