Genetic and cytogenetic studies in children with retinoblastoma

Genetic and cytogenetic studies were performed in 110 children with retinoblastoma (57 girls and 53 boys), with 70% of cases being unilateral and 30% bilateral. The mean age of the patients at diagnosis was 22.6 months in unilateral and 11.1 months in bilateral cases. Sporadic cases were 94.5%, and the remaining were familial. There was no difference when the paternal age of sporadic cases was compared with that of familial cases. Three patients from a family exhibiting unilateral retinoblastoma had an interstitial deletion at band 13q14. The presence of other neoplasms and the importance of the genetic and chromosomic studies, for the purpose of genetic counseling, are discussed.