[A genetic and clinical study of retinoblastoma in twins].

A pair of monozygotic twins, confirmed by blood grouping (ABO, MN, Rh, P), serum typing (Hp, Gc), EsD phenotyping and HLA(A, B, Cw), both developed the "cat eye" 45 days after birth; the diagnosis of retinoblastoma (Rb) was established pathologically after enucleation. From data of 33 pairs of twins with Rb in literature of this century, the concordance rate of Rb twins and genetic index of Rb (76.56%) were calculated. In addition, the reliability of zygosity determination, the "mirror image" phenomenon, and the use of the second-mutation hypothesis of Knudson for cancer initiation were briefly discussed.