Partial triplication and deletion of 13q: study of a family presenting with bilateral retinoblastomas

This report compares the pathogenetic influences of selective deletion and triplication of chromosome 13 derived from a familial 12; 13 insertional translocation. In the proband a heritable chromosomal basis for his bilateral retinoblastomas is established [46, XY, del (13) (pter q12.5::q22.qter)mat], and in his sister the relatively modest effects of triplication of the mid–portions of 13q are demonstrated [46, XX, ins(12;13) (12pter–12pll.2::13q22.113q12.5::12pll.212qter)mat]. Qualitative and quantitative gene marker studies and chromosomal staining techniques to differentiate timing of DNA replication failed to indicate functional gene changes about the breakpoints.