Dr. Susumu Makino and his colleagues found several animals that had gait abnormalities among Wistar rats maintained at Shionogi Co. They named these animals osteogenic disorder (OD) rats because they exhibited prominent bone and joint abnormalities and systemic bleeding. Subsequent studies revealed that these symptoms were derived from an ascorbic acid (vitamin C) deficiency arising from defective gulonolactone oxidase (GLO) activity. This characteristic was confirmed to be the result of a mutation involving the autosomal single recessive gene od. Scurvy due to L-gulonolactone oxidase deficincy; phenotype normalizes if supplied with ascorbic acid 300mg/kg/d. od/od rats are more susceptible to dental caries as compared with +/+ rats, in only amoun parous females.