Analysis of the dominance effect of a spontaneous recessive lethal in the mouse on homozygous and heterozygous genetic background.

A spontaneous lethal (l-15) without detectable dominant phenotypical effects has been studied in F-4 offspring on a homozygous (CBA/CBA) or a heterozygous (CBA/Ajax) genetic background. No significant dominance effect resulting in increased intra-uterine death or decreased mating ability was found irrespective of the genetic background.