Scott Syndrome in German Shepherds

The disease is characterized by bleeding abnormalities due to deficiency of platelet binding of X-factor. In affected dogs, the initiation of the coagulation cascade is impaired because their platelets fail to catalyse the conversion of prothrombin to thrombin. In a clinical setting, the syndrome is typically manifested by the formation of postoperative hematomas and minor bleeding. Non-traumatic bleeding into joints and soft tissues and nosebleeds may also occur.

The causal variant for this disorder in German Shepherd dogs is the splice-site g.8912219 G>A mutation in the TMEM16F gene, also known as ANO6.

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.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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References:

Brooks, M.B., Catalfamo, J.L., MacNguyen, R., Tim, D., Fancher, S., McCardle, J.A. :  A TMEM16F point mutation causes an absence of canine platelet TMEM16F and ineffective activation and death-induced phospholipid scrambling. J Thromb Haemost 13:2240-52, 2015. Pubmed reference: 26414452.