Sox18^ra, ragged, semidominant. Arose spontaneously in a crossbred stock. In heterozygotes the first coat develops a little more slowly than normal. The coat contains guard hairs and awls but no auchenes and very few zigzags. This gives the coat a thin ragged appearance. The agouti pattern is modified, the entire coat being unusually dark. Heterozygotes are normally viable and fertile. Homozygotes are almost completely naked. Many are edematous at birth, and almost all die before weaning. A few survive and may breed (J:86). Developmental studies have shown that in Sox18^ra/+ mice, growth of the late differentiating hair follicles which produce auchenes and zigzags is very retarded or arrested (J:12991). A low percentage of Sox18^ra/+ mice in some stocks were found by Herbertson and Wallace (J:13089) to have a white chylous fluid in the abdomen from shortly after birth until a week or so of age. The incidence of chylous ascites in these mice is affected by one or more genes unlinked to Sox18^Ra, and also by two mutant genes linked to Sox18^Ra, (fi, we) and one on a different chromosome (py, Chr 1) (J:6220).

The phenotypes of Sox18^Ra and Sox18^ra-J have been described as indistinguishable (J:51188).