Retinoblastoma and chromosome 13 deletion.

Two cases of association of unilateral and bilateral retinoblastoma, respectively, with interstitial deletions of long arms of chromosome 13 are presented. The clinical pictures of both children corresponded to the moderate extent of the deletions, with both somatic and mental retardation in both children, and mild phenotypic manifestations (hypertelorism, slight epicanthi, mild facial hirsutism, and partial syndactyly in the child with unilateral retinoblastoma). Opinions concerning the association of chromosome 13 deletion with retinoblastoma are discussed.