Connexin 26 gene mutations in non-syndromic hearing loss among kuwaiti patients

To study connexin 26 [Cx26] gene mutations among autosomal recessive non-syndromal hearing loss in Kuwaiti patients and evaluate their effect on phenotypes. This cross sectional study included 100 patients aged between 6 months and 18 years, who were referred to the Sheikh Salem Al-Ali Centre for audiology and speech evaluation of autosomal recessive non-syndromic sensorineural hearing loss confirmed by clinico-genetic evaluation and a battery of diagnostic tests. Gene profiling and sequencing were performed to detect the presence and nature of Cx26 mutation. Of the 100 patients, mutation of Cx26 gene was detected in 15 patients [15%] of which 9 [60%] cases were heterozygous and 6 cases [40%] were homozygous. Eighty per cent of the 15 Cx26 positive cases resulted from the 35delG mutation. Among the heterozygous cases, 6 [66.6%] were positive for 35delG. All 6 homozygous patients were positive for the 35delG mutation. A significant correlation was found between genetic findings [p = 0.013] and family history [p = 0.029], as well as the onset [p = 0.015], course [p = 0.033], degree and configuration of hearing loss [p = 0.001]. Among the selected Kuwaiti population sample, the Cx26 gene mutation was responsible for 15% of autosomal recessive non-syndromic sensorineural hearing loss. We recommend that screening for Cx26 gene mutation be considered in the screening strategy of patients with non-syndromic childhood hearing loss for counselling and management purposes

Segregation of acrocentric chromosome association in familial dicentric Robertsonian translocation t(14p;22p), aneuploidy (trisomy-21) and heteromorphism.

The frequency and types of acrocentric chromosome association were quantitatively analysed in a Down syndrome child with unusual karyotype, 46, XX, -14, -22, t dic (14p;22p), +21, 21S+. Father and 4 sibs were heterozygous carriers for t dic (14p;22p). The variant 21S+ was inherited from the mother. The occurrence of translocation and trisomy in the same individual is extremely rare. Acrocentric chromosome association was analysed in this interesting family to understand the interrelationship of acrocentric chromosome association, Robertsonian translocation and heteromorphism, as possible predisposing factors for nondisjunction. Our findings suggest that acrocentric chromosome association is a heritable and nonrandom phenomenon. Heterozygous carriers for translocations and variants are likely to be at increased risk of nondisjunction. Long term family studies will enable to ascertain the causal-relationship of these factors more precisely.

Familial fragile secondary constriction on chromosome 2 (2q11) with unusual features and psychomotor retardation.

A child with fragile secondary constriction 2q11 associated with unusual clinical features and psychomotor retardation is described. The pathogenetic significance of this fragile site still remains unclear, and heterogeneity of clinical manifestations is not well understood.