Breeds Affected: Cavalier King Charles Spaniel
Samples Accepted: Blood, Buccal Swabs
Disease Information: Muscular dystrophy (Duchenne-type) or DMD, is a disorder in which muscle fiber degeneration leads to weakness, a “bunny hop” gait, difficulty opening the jaw, curvature of the spine, and muscle wasting. Affected pups can be identified at 8-10 weeks of age. The disease is fatal.
Inheritance Information: DMD is X-linked recessive, because the DMD gene is located on the X-chromosome.
The possible genotypes are:
XX This dog is a normal female.
XXDMD This dog is a carrier female. She is clinically normal, but will pass the mutation (XDMD) to 50% of her offspring. When bred to a normal male, she can have pups of all four genotypes: normal female (XX), carrier female (XXDMD), normal male (XY), and affected male (XDMDY).
XY This dog is a normal male.
XDMDY This dog is an affected male.
– Female offspring of a carrier female should be genetically tested to determine if they are normal or carriers (XX or XXDMD).
– Carrier females (XXDMD) should not be bred, because affected males can be produced.
– Affected males (XDMDY) should not be used for breeding.
Test Information: This mutation test identifies a single base change in exon 50 of the DMD gene.
Walmsley, GL., Arechavala-Gomeza, V., Fernandez-Fuente, M., Burke, MM., Nagel, N., Holder, A., Stanley, R., Chandler, K., Marks, SL., Muntoni, F., Shelton, GD., Piercy, RJ.: A duchenne muscular dystrophy gene hot spot mutation in dystrophin-deficient cavalier king charles spaniels is amenable to exon 51 skipping. PLoS One 5:e8647, 2010. Pubmed reference: 20072625. DOI: 10.1371/journal.pone.0008647
Further information is available at the Online Mendelian Inheritance in Animals website.