Linkage of hooded and hood-modifier genes in the rat.

The linkage of hooded (h) and hood-modifier (Hm) loci was studied in the backcross of inbred rat strains (ACI X DI)F1 X DI. Four distinct hooded phenotypes were found in 128 offspring. Two had the parental phenotype and two were recombinants. The results of statistical analyses showed that the h and Hm autosomal loci are linked; the corrected distance is 47 +/- 4 cm. The Hm gene is transmitted in normal Mendelian pattern and has two alleles that manifest short (HmS) or long (HmI) pattern of the hooded pigmentation.