Breeds Affected: German Shepherd Dog, White Shepherd Dog, mixes
Samples Accepted: Blood, Buccal Swabs
Disease Information: Affected pups can be identified at birth by the lack of hair on areas of their head and lower back. Some teeth may be absent or abnormally shaped, and the dogs cannot produce normal tears, so eye problems may develop. Nasal discharge and respiratory problems are also common.
Inheritance Information: Ectodermal Dysplasia is X-linked recessive, because the EDA gene is located on the X-chromosome. Male animals with the mutation (which have only one X chromosome) are affected. Females may have one normal and one mutated version and be asymptomatic carriers.
The possible genotypes are:
XX This dog is a normal female.
XXed This dog is a carrier female. Carrier females of this disorder may occasionally show mild symptoms of the disorder, and will pass the mutation (Xed) to 50% of her offspring. When bred to a normal male, she can have pups of all four genotypes: normal female (XX), carrier female (XXed), normal male (XY), and affected male (XedY).
XY This dog is a normal male.
XedY This dog is an affected male. When bred to a normal female, all daughters will be carriers (XXed), but all sons will be normal (XY).
– Female offspring of a carrier female should be genetically tested to determine if they are normal or carriers (XX or XXed).
– Carrier females (XXed) should not be bred, because affected males can be produced. Some carrier females may also have mild symptoms of the disorder.
– Affected males (XedY) should not be used for breeding.
Test Information: This mutation test identifies a single base change in intron 8 in the EDA gene.
Casal, ML., Scheidt, JL., Rhodes, JL., Henthorn, PS., Werner, P.: Mutation identification in a canine model of X-linked ectodermal dysplasia. Mamm Genome 16:524-31, 2005. Pubmed reference: 16151697. DOI: 10.1007/s00335-004-2463-4
Further information is available at the Online Mendelian Inheritance in Animals website.