Congenital Osteochondrodysplasia with Systemic Subcutaneous Edema (ocd/ocd): A New Lethal Autosomal Recessive Mutant of the Rat

The inheritance of a new lethal mutant rate showing congenital osteochondrodysplasia with systemic subcutaneous edema (ocd for the gene symbol) was examined by crossings between the carriers and between F1s derived from the carrier x Long-Evans crossing. The ratio of the affected to phenotypically normal was 276:89 in pups derived from the crossings between the carriers and 83:17 in those at the LE-F2 generation derived from the proven carriers of the LE-F1 animals, thus showing that the ratio is 3:1. The female:male ratio was 47:42 in the affected and 133:143 in the phenotypically normal pups, showing the sex ratio is 1:1, irrespective of the affected or phenotypically normal. The ratio of affected:carrier:noncarrier was 26:58:27 in littermates derived from the crossings between the carriers, showing the ratio is 1:2:1. The results fitted well to the hypothesis that the inheritance is a single autosomal recessive trait. Independence of the gene from linkage group I was also revealed, because the ratio of colored to albino was 14:3 and 65:18 in affected and phenotypically normal pups at the LE-F2 generation, respectively, which fitted to the ratio of 3:1.