Incidence of genetic factors in the causation of deafness in childhood.
Routine investigations of 1568 children with severe-profound hearing loss, during a 15 years' period, revealed the following classification: Hereditary Deafness 25%, Acquired Deafness 43% (prenatally 11%, perinatally 16%, postnatally 16%), Unknown Deafness 32%. This group of unknown causes is usually large in any surgery of deafness and in many of these children deafness is believed to have a genetic basis. In the light of this premise, we performed more careful genetic and clinical investigation in 268 children coming under observation in the 3 last years. Moreover, we examined a group of 44 asymptomatic parental pairs of these children to determine if any were carriers of genes for deafness. The criteria used for identification were: pure tone audiometry, speech discrimination score, threshold of the acoustic reflex, Lüscher test, loudness discomfort level for 1-2-4 kHz, continuous Bekesy audiometry. Children follow-up enabled us to place 14 cases in the range of hereditary syndromes. Therefore, the group of unknown deafness decreased from 32% to 27%. The audiological investigation, performed on the parental pairs, pointed out an abnormal auditory function in 30.6% of subjects, who for these reasons should be considered as heterozygous carriers.
Lenzi
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Department of Audiology, University of Milan, Italy.
Zaghis
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D002648:Child; D003638:Deafness / Q000151:congenital / Q000235:genetics*; D005128:Eye Diseases / Q000235:genetics; D006042:Goiter / Q000235:genetics; D006331:Heart Diseases / Q000235:genetics; D006801:Humans; D009083:Mucopolysaccharidoses / Q000235:genetics; D009394:Nephritis, Hereditary / Q000235:genetics; D010003:Osteoarthritis / Q000235:genetics; D012174:Retinitis Pigmentosa / Q000235:genetics; D013575:Syncope / Q000235:genetics; D013577:Syndrome