Beverly R. Rollnick

1207 FAMILIAL FACTORS IN SYNDROMIC AND NON-SYNDROMIC EAR MALFORMATIONS

Ear malformations, minor or severe, occur in 1% of the population. When observed in combination with other anomalies, a wide variety of syndromes has been identified. We surveyed 350 patients with ear malformations, of whom 45 subjects with monogenic syndromes were identified. Of interest were families of probands with the Treacher Collins syndrome, an autosomal dominant (AD) disorder with incomplete penetrance; a high percentage of cases are assumed to result from new mutation. In 2/32 families, 2 affected siblings were born to phenotypically normal parents with negative family history, suggesting that caution be exercised in genetic counselling in this situation. Patients not identified as having monogenic syndromes are being evaluated to assess familial factors in the etiology of ear malformations. Ear anomalies were found to be familial in 32/84 families studied. In familial cases, pedigrees appeared to be suggestive of AD inheritance with incomplete penetrance, or of multifactorial inheritance. 8.8% (33/376) of first-degree relatives exhibited ear anomalies. The following conclusions are suggested: 1) The presence of an ear malformation should alert the clinician to the possible presence of a syndrome with a high recurrence risk; 2)Apparently non-syndromic ear malformations are often familial; genetic counselling with recurrence risk estimation is indicated.Supported by grant DE02872, National Institutes of Health