Chromosomal anomalies in patients with retinoblastoma.

Karyotypes from 50 persons with retinoblastoma confirmed by histopathological examination were studied by conventional staining and Giemsa-banding techniques. Two chromosomal anomalies were found. An interstitial deletion of the long arm of No. 13 chromosome was identified by Giemsa-banding in the karyotypes from a boy with unilateral retinoblastoma. Another boy with unilateral tumor had a karyotype of 47,XXY. These findings provide additional evidence that a deletion of chromosome No. 13, most likely involving band 13q14, is associated with the development of retinoblastoma. In conjunction with other reports, our findings also suggest that retinoblastoma may be found more frequently in children with chromosomal aneuploidy.