Sensorineural Hearing Impairment is a Common Feature of Consanguineous Marriage

Abstract

Introduction: Sensorineural hearing loss (SNHL) accounts for about 60%
of all hearing loss. This is sometimes also called “Nerve deafness”. The term “Sensorineural” is used to indicate that there is either a cochlear or an eight nerve lesion. The diagnosis of sensorineural hearing loss is made through audiometry, which shows a significant hearing loss without “The air-bone gap” that is characteristic of conductive hearing disturbances.
Among various risk factors described for deafness, consanguinity is an established high risk.
Aim of the Work: This work was carried out to study the prevalence of sensorineural hearing loss in offsprings of consanguineous marriage, who attended the Medical Genetics Center, Ain Shams University.
Patients and Methods: The study was performed on 950 children with congenital hearing loss.
Results: Consanguineous marriage was present in 71.2% of studied cases, 47.3% of these cases, parents were 1st cousin, in 36.7% parents were 2nd cousin, 16% had remote consanguinity. 28.8% of cases were the offspring of non-consanguinous marriage. Also, the results showed that 44.2% of cases had severe degree of sensorineural hearing loss (71-90 dBHL), 24.3% had profound hearing loss (>90 dBHL). Autosomal dominant inheritance (AD) hearing loss was detected in 40% of cases. Autosomal recessive inheritance hearing loss was discovered in 27% of cases, and in 18.7% of study cases the hearing loss was
associated with genetic syndromes, where 88.8% of these cases were associated
with Down syndrome.
Conclusion: The incidence of hereditary hearing impairement is commoner in developing counteries compared to developed counteries, so, prevention is essential to reduce the incidence of genetic hearing loss. Premarital and antenatal screening should be applied whenever possible, at least for those at risk of developing genetic diseases including hearing impairement.

Keywords: Consanguinity; hearing disorders;
preventive medicine.

Egypt. J. Hum. Genet Vol. 9 (1) 2008: pp. 85-92