A presumed deletion covering theWandPhloci of the mouse

Abstract

SUMMARY: A new allele at theW-locus (W^19H), found in a mutagenesis experiment in which females were irradiated, involves a presumed deletion. The deletion covers thePhlocus (which forms part of a gene complex with theW,PhandRwloci), and the locus of a recessive lethal 2 cM distal toW. It does not extend distally to thebllocus; nor does it involve theRwlocus,W^19H/Rwcompounds being viable and fertile. Thus, the length of the deletion is 2–7 cM. The non-involvement ofRwshows that, in the gene tripletRw,W,Ph,Rwmust lie proximal toWandPh, whose relative position remains unknown. Heteozygotes forW^19Hare not anaemic, show only minimal white spotting and no pigment dilution; they thus resemble heterozygotes for the originalWmutant allele and differ fromW/Phtrans heterozygotes, which have extensive white spotting. In additionW^19Hheterozygotes may be small and runted, many are believed to die prenatally, and some in the nest. Their radiosensitivity is increased. Homozygotes die at the pre-implantation stage.