Genetic study of syndromic inherited deafness

ABSTRACT

The study comprised 25 patients with Syndromic genetic hearing loss. They were selected from the Audiology Unit, Faculty of Medicine, and the Human Genetics clinic, Medical Research Institute, Alexandria University. Their ages ranged from 2.5 to 19 years. Males were more affected than females [M/F ratio = 21]. The high parental consanguinity [63.2%] emphasizes the contribution of autosomal recessive gene or multiple genes in the etiology of deafness. Thorough clinical examination, and complete investigation including metabolic screening tests, cytogenetic studies and other specific investigations, together with pedigree analysis were the main criteria for diagnosis. Fundus examination was essential as ocular involvement was found in association with most cases of genetic hearing loss. Results of the studied patients revealed that deafness was inherited either dominantly, recessively or in X-linked manner in association with other anomalies in the following syndromes Down syndrome [one case, 4%], external ear malformation [4%], distal arthrogryposis [one case, 4%], Optic atrophy and ataxia [one case, 4%], Stickler-Wagner syndrome [one case, 4%], Usher syndrome [2 cases, 8%], Waardenburg syndrome types I and II [2 cases, 8%], Charcot-Marie-Tooth syndrome [2 cases, 8%], Alport syndrome [3 cases, 12%], Pendred syndrome [5 cases, 20%], and Hunter syndrome [3 cases, 12%]. For the idiopathic cases [2 cases, 8%], a possible genetic cause was also suggested, probably autosomal recessive