[Causes of pre-verbal deafness in an institutionalized population, emphasizing genetic etiology]

To investigate the causes of pre-verbal deafness in an institutionalized population emphasizing genetic etiology, considering the scarceness of national data in this field.

Based on the promptuaries of 658 pupils from 18 institutions for deaf people in Recife, information about audiological tests, laboratory examinations, etiology, associated anomalies, consanguinity and other deaf persons in the family was obtained; dysmorphologic examination was performed in 557 pupils; all the families with recurrent cases of deafness were investigated, having the pertinent pedigrees been constituted.

About 13% of the studied population probably manifest genetic deafness; the autosomal recessive, autosomal dominant and X-linked recessive patterns of inheritance were observed, respectively, in 87.7%, 8.8% and 3.5% of the familial cases; among the examined pupils, 4.3% presented specific dysmorphic syndromes or anomalies associated with deafness; the acquired causes and unknown etiology were represented by 41.5% and 45.5% respectively.

Obtained frequencies for the distinct causal factors of pre-verbal deafness are within the spectrum of variation of the frequencies observed in similar works, pointing out that in a great number of cases the etiology is unknown.