Single gene inheritance of occurrence of head spots in mice

Abstract

Results from earlier selection studies indicated that while the size of head spots in mice descended from the Goodale head-spot strain was a quantitative, polygenic trait, head-spot occurrence was probably a qualitative trait inherited by one or two genes. The present study was undertaken to examine this possibility by crossing a head-spot stock with three inbred strains and with two noninbred stocks carrying mutant genes. Observed segregation ratios in the F2 and backcross generations of these crosses were compared to results expected under various models of qualitative inheritance. Evidence of linkage between known loci and a putative head-spot gene also was sought. Results indicated that head spotting was inherited primarily by the action of a recessive autosomal gene, head spot (hs). The action of this gene was subject to modification, in some crosses, by other genes or by environmental factors. Attempts to demonstrate linkage between the head spots and known single-locus traits were unsuccessful.

Strain‐Specific White‐Spotting Patterns in Laboratory Mice

“…Doolittle (1979) used random breeding, inbreeding, and selection techniques to demonstrate that the occurrence of spots in mice descended from the Goodale (1937) stocks was controlled by a single major gene locus, while spot size was controlled by a polygenic quantitative inheritance system. Spot size is also influenced by gender, parity and age of dam (Wildman and Doolittle, 1986), suggesting an influence of growth rate or other nonspecific variables, and by background coat color (Lamoreux and Russell, 1979;Lamoreux, 1983). Thus, the presence of a major spotting gene is not a simple predictor of the white-spotting phenotype.…”

Population Genetics

“…The average effect of the substitution of A1 for A2 is The hs gene in mice causes white head spots (Wildman 1984, Wildman andDoolittle 1986). There are q A2 genes in the population; therefore, we can substitute A1 for A2 with frequency q.…”