Retinoblastoma in a boy with a de novo mutation of a 13/18 translocation: the assumption that the retinoblastoma locus is at 13q141, particularly at the distal portion of it.

In serial cytogenetic examinations of peripheral lymphocytes from retinoblastoma patients, we found a patient with sporadic bilateral retinoblastoma with a de novo mutation of a 13/18 translocation, with their respective breakpoints at 13q141 and 18q122. The simultaneous de novo occurrence of retinoblastoma and the chromosomal rearrangement involving 13q14 in the proband suggests that the gene locus for retinoblastoma is at 13q141, particularly at the distal portion of it. Deletion mapping data are compatible with this suggestion.