A genetic aetiological 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 (UAE) in whom a known acquired cause for their deafness had been excluded. Four schools in four different Emirates participated in the study (Sharjha, Khor Fakan, Dubai and Al-Ain). In each child a detailed history was obtained. This included a detailed family history, the level of consanguinity between the parents, ethnic origin, and the age of onset and progression of the deafness. The deafness was classified into syndromic and non-syndromic groups. These were then subdivided into autosomal 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 and 60 (81 per cent) had non-syndromic deafness. Overall there was a high prevalence of AR deafness (92 per cent) with AD deafness constituting 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, AD 43 per cent, with no X-linked or sporadic cases. In the non-syndromic 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 positive family history, 54 per cent of those had affected siblings, 50 per cent of which had more than one affected sibling. However, almost all the parents were not aware that the deafness in their children was genetic in origin.