Breeds: Chinese Crested Dog, Mexican Hairless Dog (Xoloitzcuintli), Peruvian Hairless Dog (Inca Hairless)
Samples Accepted: Blood, Buccal Swabs
Trait Information: Ectodermal dysplasia results in varying amounts of hairlessness over all or most of the body; tufts may be present on the head, feet, and tail. Teeth may be abnormal or some might be missing.
Inheritance Information: Hairlessness is autosomal dominant, meaning that animals with just one copy of this allele will show the phenotype, and 50% of their offspring will also show this trait. Hairlessness is homozygous lethal, thus animals with two copies of the allele will not be born.
The possible genotypes are:
n/n The dog has a normal coat (in Chinese Crested, this is known as Powder Puff), and normal teeth.
H/n The dog is all or mostly hairless, and may have abnormal teeth.
– All dogs can be used for breeding, to maintain genetic diversity. If two Hairless (H/n x H/n) are bred, 25% of the offspring will be hairless embryonic lethal (H/H) and will not be born. 50% will be hairless (H/n) and 25% will have hair (n/n). Litter sizes will thus be smaller than normal, as 25% of the embryos will not carry to term. The live offspring will therefore be approximately 33% normally haired and 66% hairless. Breeding hairless (H/n) to normally haired (n/n) dogs will produce 50% hairless and 50% normally haired offspring.
Test Information: This mutation test identifies a duplication in the FOXI3 gene.
Drögemüller, C., Karlsson, E.K., Hytönen, M.K., Perloski, M., Dolf, G., Sainio, K., Lohi, H., Lindblad-Toh, K., Leeb, T.: A mutation in hairless dogs implicates FOXI3 in ectodermal development. Science 321:1462, 2008. Pubmed reference: 18787161. DOI: 10.1126/science.1162525
Further information is available at the Online Inheritance in Animals website.