FAMILIAL OCCURRENCE OF UNILATERAL VESTIBULAR SCHWANNOMA

Vestibular schwannoma (VS) may present clinically in one of two forms: sporadic unilateral or hereditary bilateral. Almost all cases of fami lial transmission have been associated with the diagnosis of neurofibr omatosis type II (NF-2). In this report, we describe nine families (18 individuals) presenting with unilateral VS without evidence of NF-2, In four of the nine families, the affected individuals were of parent- offspring relationship, in three families they were cousin-cousin, and in the remaining two families, they were sibling-sibling and aunt-nep hew. No other members of the families were diagnosed with NF-2. There was no evidence for gender predilection or genomic imprinting among af fected individuals. This study suggests that familial occurrence of un ilateral VS may be genetically inherited as it occurs more commonly th an would be estimated by chance alone. Future genetic studies will elu cidate whether occurrence of unilateral VS in these families represent s a variable expression of NF-2, chance occurrence of unilateral VS in families, or a new genetic disorder.