Frequency of occurrence of recessive 35delG mutation in GJB2 gene in children with sensorineural hearing loss

Introduction: A human being is known to have about 100 genes associated with deafness and hearing loss, which are located in both the nucleus and mitochondria. Most commonly detected mutations are those in the GJB2 gene, mononucleotic deletion 35 delG including, which accounts for up to 50% of cases of neurosensory hearing loss in Europeans.We studied frequency of occurrence of the above-mentioned mutation among Belarusian schoolchildren with the impaired hearing. Methods: 35delG mutation was detected with the help of blood's polymerase chain reaction. The children's parents were asked about the presence of risk factors and timely diagnosis of sensorineural hearing loss by means of questionnaires.Results: 68 children aged 6-19 years old with severe to profound bilateral sensorineural hearing loss (according to the WHO classification) were examined. Autosomal recessive genotype was detected in 51.4%, heterozygous genotype in 2.9% of children.The questionnaires showed that impaired hearing was first noted by the parents when the child was under 1 year old in 42.6%, from 1 to 3 years old in 38.2%, and above 3 years old in 19.1% of children.Reasons for impaired hearing as reported by the parents were as follows: ototoxic antibiotics intake in 32.3%, heredity in 30.9%, unknown factors in 25%, other factors in 11.8% of children.Conclusion: The conducted study demonstrates frequent occurrence of 35delG nuclear mutation (53.4%) in sensorineural hearing loss in children from Minsk-city. Possible risk factors for sensorineural hearing loss such as ototoxic antibiotics intake and heredity have been determined. Impaired hearing loss has been noted by parents in almost half of the children (42.6%) under 1 year old