Complementation analyses for 45 mutations encompassing the pink-eyed dilution (p) locus of the mouse

The homozygous and heterozygous phenotypes are described and characterized for 45 new pink-eyed dilution (p) locus mutations, most of them radiation-induced, that affect survival at various stages of mouse development. Cytogenetically detectable aberrations were found in three of the new p mutations (large deletion, inversion, translocation), with band 7C involved in each case. The complementation map developed from the study of 810 types of compound heterozygotes identifies five functional units: jls and jlm (two distinct juvenile-fitness functions, the latter associated with neuromuscular defects), pl-1 and pl-2 (associated with early-postimplantation and preimplantation death, respectively), and nl [neonatal lethality associated with cleft palate (the frequency of rare "escapers" from this defect varied with the genotype)]. Orientation of these units relative to genetic markers is as follows: centromere, Gas-2, pl-1, jls, jlm p, nl (equatable to cp 1 = Gabrb3); pl-2 probably resides in the c-deletion complex. pl-1 does not mask preimplantation lethals between Gas2 and p; and no genes affecting survival are located between p and cp1. The alleles specifying mottling or darker pigment (generically, pm and px, respectively) probably do not represent deletions of p-coding sequences but could be small rearrangements involving proximal regulatory elements.