Multiple lipomas linked to an RB1 gene mutation in a large pedigree with low penetrance retinoblastoma

Hereditary predisposition to lipomas is observed in familial multiple lipom atosis (OMIM 151900) and benign cervical lipomatosis (OMIM 151800) and can also be associated with mutations in the MEN1 and PTEN genes (OMIM 131100 a nd 153480, respectively). In addition, a recent report indicates that a few patients with hereditary retinoblastoma also have lipomas. Here we report on an extended family segregating a splice site mutation in the RB1 gene. A lmost all adult carriers of this mutation had multiple lipomas while penetr ance for retinoblastoma was incomplete. In an unrelated pedigree, which was reported previously, the identical mutation was only associated with low-p enetrance retinoblastoma but not lipomas. Our data indicate that lipoma pre disposition in hereditary retinoblastoma is not associated with specific RB 1 gene mutations but is influenced by modifying factors linked to this gene .