A GENETIC ETIOLOGIC SURVEY OF SEVERE CHILDHOOD DEAFNESS IN THE UNITED-ARAB-EMIRATES

The aim of this study was to provide a genetic aetiological survey of children attending classes for the deaf in the United Arab Emirates (U AE) in whom a known acquired cause for their deafness had been exclude d. Four schools in four different Emirates participated in the study ( Sharjha, Khor Fakan, Dubai and Al-Ain). In each child a detailed histo ry was obtained. This included a detailed family history, the level of consanguinity between the parents, ethnic origin, and the age of onse t and progression of the deafness. The deafness was classified into sy ndromic and non-syndromic groups. These were then subdivided into auto somal recessive (AR), autosomal dominant (AD), X-linked recessive (XR) , and sporadic. A total of 74 children from 51 families were included in the study. Fourteen of these (19 per cent) had syndromic deafness a nd 60 (81 per cent) had non-syndromic deafness. Overall there was a hi gh prevalence of AR deafness (92 per cent) with AD deafness constituti ng 7 per cent and sporadic deafness 1 per cent, and no X-linked cases. In the syndromic group AR syndromes comprised 57 per cent of cases, A D 43 per cent, with no X-linked or sporadic cases. In the non-syndromi c group almost all cases were AR (98 per cent), with no AD or X-linked cases, and one sporadic case. The level of consanguinity in the study group was 74 per cent with a high number of complexly consanguineous families (34 per cent). Eighty-six per cent of the children had a posi tive family history, 54 per cent of those had affected siblings, 50 pe r cent of which had more than one affected sibling. However, almost al l the parents were not aware that the deafness in their children was g enetic in origin.