Genetic hearing loss: a study of 228 Brazilian patients

Abstract

We studied 228 patients, with suspected or confirmed genetic hearing loss, in order to determine the clinical and genetic diagnoses and etiology of each case. Deafness with no associated abnormalities was found in 146 patients (64%) belonging to 112 families. Syndromic deafness was diagnosed in 82 patients (36%) belonging to 76 families. The genetic etiology was as follows: autosomal recessive inheritance in 40.8% of syndromics and non-syndromics, autosomal dominant inheritance in 13.2% and X-linked recessive in 1.3%. In 44.7% of the cases, the etiology of the hearing loss could not be determined. Monogenic causes are the most possible etiology in the latter cases. Parental consanguinity was found in 22.4% of the cases, and deafness was bilateral, profound and neurosensorial in 47.4% of the patients. An early onset of hearing loss (< 2 years of age) occurred in 46.5% of the cases. These results are similar to previous literature reports.

Study of the hearing loss in children and adolescents, comparing the periods of 1990–1994 and 1994–2000

“…In the period of 1994-2000, however, less cases were detected than in the previous period. In the study by Longhitano and Brunoni [12], consanguinity occurred in 22.4% of the cases.…”

“…It is possible that patients affected by familial and syndromic hearing loss could be seeking the multidisciplinary attention offered by that service, which published a study [12] including 228 individuals affected by hearing loss, including some of the patients studied here, in which the authors found isolated deafness without association with other anomalies in 64% of the cases; in the remaining 36%, deafness was syndromic. The inheritance was recessive autosomal in 40.8%, dominant autosomal in 13.2% and connected to the X chromosome in 1.3% of the cases.…”

Perda auditiva hereditária: relato de casos

“…Analisandose as duas casuísticas como um todo, os casos de perda auditiva isolada predominaram sobre os sindrômicos, com 59,6% do total (112 famílias em 188). Quanto ao padrão de herança 49,9% entre sindrômicos e não-sindrômicos foram de herança autossômica recessiva e 10,6% foram de herança autossômica dominante 12 .…”