Consanguinity and hearing impairment in developing countries: a custom to be discouraged.

Consanguineous marriage is a tradition which is commonly practised among Asian, African, and Latin American communities whether they are living in their own countries or settled in Europe or the USA. These communities, in addition to their custom of interrelated marriage, have large families and are a rapidly growing population. The siblings of consanguineous marriages have a significantly higher incidence of autosomal recessive diseases including hearing impairment. Two epidemiological surveys were carried out 10 years apart. There were 6,421 subjects from Riyadh City and 9,540 from all other parts of the Kingdom of Saudi Arabia. A random sample was examined otologically and a questionnaire was filled in that included age, sex, family relation, number of siblings, etc. ENT examination and audiological assessment were performed. Consanguinity was found among 22 per cent as first cousins and 23 per cent as second cousins in the first survey. In the second survey 19 per cent were first cousins and 28 per cent second cousins. The rate of consanguinity was 45 per cent in the first survey and 47 per cent in the second. The prevalence of hereditary sensorineural hearing loss (SNHL) was 66.07 per cent and 36.6 per cent in the first and second survey respectively. The incidence of hereditary hearing impairment is very high in developing countries compared to developed countries. Prevention is essential to reduce the incidence of genetic hearing loss. Consanguinity should be discouraged through health education of the public about the adverse effect of interrelated marriage. Genetic counselling, premarital and antenatal screening are to be applied whenever possible, at least for those at risk of developing genetic diseases including hearing impairment.