Frequency of the severe combined immunodeficiency disease gene among horses in Morocco.

Severe combined immunodeficiency disease (SCID) of horses is an autosomal, recessive hereditary disease occurring among Arabian or crossbred Arabian horses. The genetic defect responsible was previously identified as a 5-base pair deletion in the gene encoding the catalytic subunit of the DNA dependant protein kinase (DNA-PKcs). This study was carried out to determine the frequency of SCID and identify horses carrying the gene for SCID among Arabian and Arabian crossbred stallions and mares in Morocco using a DNA-based test. Twenty-one horses were SCID carriers: 14 (7%) Arabians, 6 (4%) Arab-Barbs and one (33%) Anglo-Arab. After analysing their genealogy, 3 imported stallions were identified that disseminated the mutant gene of DNA-PKcs in Morocco.