
Testing of dogs: MDL in AmStaf
Muscular dystrophy, Ullrich type (MDL) in American Staffordshire Terrier
Ullrich muscular dystrophy is a rare genetic disorder that disrupts the function of collagen VI, which is important for the structural integrity of muscle and connective tissue. Clinical manifestations usually appear in puppies and include mainly muscle weakness and excessive joint mobility.
In American Staffordshire Terriers, the disease is caused by the c.6398del mutation in the COL6A3 gene.
The mode of inheritance of the mutation is autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.
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Reference:
Jankelunas, L., Murthy, V.D., Chen, A.V., Minor, K.M., Friedenberg, S.G., Cullen, J.N., Guo, L.T., Mickelson, J.R., Shelton, G.D. : Novel COL6A3 frameshift variant in American Staffordshire Terrier dogs with Ullrich-like congenital muscular dystrophy. J Vet Intern Med 37:2504-2509, 2023. Pubmed reference: 37706358.