MOLECULAR ETIOLOGY OF LOW-PENETRANCE RETINOBLASTOMA IN 2 PEDIGREES

In one family with low-penetrance retinoblastoma, a germ-line deletion is shared by affected and unaffected, obligate carriers. The deletion encompasses exon 4 of the retinoblastoma gene and corresponds to a mu tant protein without residues 127-166. In a second family, RFLP analys is shows that two distant relatives have independently derived mutatio ns. These families, together with others reported elsewhere, indicate that attributes of alleles at the retinoblastoma locus specify penetra nce.