title: Preferential mutation of paternally derived RB gene as the initial event in sporadic osteosarcoma.
abstract: Successive loss of function of both alleles of the retinoblastoma susceptibility gene (RB) on human chromosome 13 seems to be critical in the development of retinoblastoma and osteosarcoma. In cases where the tumour is familial and susceptibility is inherited, a mutation in one of the alleles is carried in the germline. We have recently shown that cytogenetically visible germline mutations are usually in the paternally derived gene. Such a bias would not be expected for sporadic (non-familial) tumours, where both mutations occur in somatic tissue, but there has been some indication of a bias towards initial somatic mutation in the paternally derived gene on chromosome 11 in sporadic Wilms tumour. We have now examined 13 sporadic osteosarcomas and find evidence which indicates that in 12 cases the initial mutation was in the paternal gene, suggesting the involvement of germinal imprinting in producing the differential susceptibility of the two genes to mutation.
authors.affiliation: Radiation Biology Center, Faculty of Medicine, Kyoto University, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Toguchida
authors.forename: K
authors.initials: K
authors.lastname: Ishizaki
authors.forename: M S
authors.initials: MS
authors.lastname: Sasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Ikenaga
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Sugimot
authors.forename: Y
authors.initials: Y
authors.lastname: Kotoura
authors.forename: T
authors.initials: T
authors.lastname: Yamamuro
mesh_terms: D015139:Blotting, Southern; D002882:Chromosomes, Human, Pair 13; D006801:Humans; D009154:Mutation; D012516:Osteosarcoma / Q000235:genetics*; D012175:Retinoblastoma / Q000235:genetics*