Dwarfism in Vizslas - skeletal dysplasia 3 (SD3)

Skeletal Dysplasia 3 (SD3) is a moderate form of disproportionate dwarfism in the Vizsla breed. Affected dogs have short legs and their height at withers is reduced by an average of 11 cm compared to unaffected dogs. The long bones of the limbs are markedly shortened and thickened with flattened articular surfaces. Femoral deformity leads to subluxation of the hip joint and secondary deformity of the acetabulum.

The defect is caused by a c.673T>C missense mutation in the PCYT1A gene, which encodes phosphocholine cytidylyltransferase alpha.

Mutation that causes SD3 in labrador retrievers is inherited as an autosomal recessive trait. That means the disease affects dogs with P/P (positive / positive) genotype only. The dogs with P/N (positive /negative) genotype are clinically without any symptom. They are genetically considered carriers of the disease (heterozygotes). In offspring of two heterozygous animals following genotype distribution can be expected: 25 % N/N (healthy non-carriers), 25 % P/P (affected), and 50 % N/P (healthy carriers). Because of high risk of producing affected offspring, mating of two N/P animals (carriers) can not be recommended.

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References:

Ludwig-Peisker, O., Ansel, E., Schweizer, D., Jagannathan, V., Loechel, R., Leeb, T. : PCYT1A missense variant in Vizslas with disproportionate dwarfism. Genes (Basel) 13:2354, 2022. Pubmed reference: 36553621