HEREDITARY ACHONDROPLASIA IN THE RABBIT : III. GENETIC ASPECTS; GENERAL CONSIDERATIONS.

Hereditary achondroplasia (chondrodystrophia foetalis) in the rabbit has been described in the present and preceding papers (1, 2). It is the first instance of this abnormality in rodents to be reported. The variation arose in pure bred Havana stock. The abnormality is determined by the expression of a simple recessive unit factor, affected individuals being homozygous for the factor. Females are somewhat more frequently affected than males, but the character is not sex-linked. Rabbits heterozygous for the factor as determined by appropriate breeding tests have a perfectly normal appearance at birth and in later life. The condition appears to be determined solely by the genetic constitution of the animal. Attention was drawn to the fact that although the development of the achondroplastic form proceeds to birth at term, death regularly occurs at the time of or very shortly after parturition. This feature of the condition is briefly discussed.