A mutant rat with congenital skeletal abnormalities and polycystic kidneys.

The newly found mutant rat was characterized by small body size, shortened broad skull, slightly shortened limbs and flattened thorax due to shortened ribs and lordosis of thoracic vertebrae. Another distinctive feature of this mutant was polycystic kidneys. The reproductive ability was poor and it died at 6-11 months of age. These constitutional skeletal abnormalities and polycystic kidneys were found to be inherited by an autosomal recessive gene, to which the gene symbol, chi, was proposed.