[Hereditary tumors and chromosome aberrations with special reference to retinoblastoma].

An absence of gene(s) on the Rb locus of chromosome 13 or a disturbance of its normal expression in the retinoblasts of the embryonic retina predisposes an individual to the development of retinoblastoma. Chromosome aberrations involving 13q14 comprised about 14% of newly arising germinal mutations. Chromosome analysis of retinoblastoma tumor cells revealed that the generation of an extra copy of the long arm of chromosome 1 or the short arm of chromosome 6 is an early event in many of the tumors and plays a significant role in engendering tumorigenicity of retinoblasts already having one mutation at the Rb locus.