Genetic test that detects the two known variants of the KRT71 gene responsible, respectively, for the hairless coat of the Sphynx and the curly coat of the Devon rex. Both are distinct alleles of the same locus and can combine in compound animals with an intermediate phenotype. The test allows carriers to be distinguished from non-carriers and prevents the birth of compound animals. It does not detect other curly-coat variants (Cornish rex, Selkirk rex).

The SPH variant is specific to the Sphynx and to lines with Sphynx introgression. The DRX variant is specific to the Devon rex. Limited data on the actual frequency of carriers in unscreened populations and in derived breeds.

- Sphynx homozygote SPH/SPH: almost hairless skin with sparse fine down, whiskers absent or fragile\n- Devon rex homozygote DRX/DRX: short, curly, soft coat, curved whiskers\n- Heterozygote SPH/+: apparently normal coat (silent carrier)\n- Compound SPH/DRX: intermediate phenotype with very sparse, fine coat\n- Tendency to seborrhoea and dermatitis in the skin folds of hairless animals

The Sphynx mutation comes from a Canadian line originating in 1966 from the kitten 'Prune', in Ontario. The Devon rex mutation comes from a curly-coated male called 'Kirlee' found in Devonshire (United Kingdom) in 1960. The common molecular basis was resolved in the 2010s when distinct variants of the KRT71 gene were identified for each breed. Historically the Sphynx was crossed with the Devon rex to broaden the Sphynx gene pool, which produced compound animals and prompted the development of specific tests for each allele.

- Screen every Sphynx and Devon rex breeding animal before mating\n- Do not mate two carriers of the same variant: risk of affected offspring\n- Expressly avoid Sphynx × Devon rex matings: they produce SPH/DRX compounds with an unwanted intermediate phenotype and increased dermatological risk\n- Carriers can be paired with clear animals, progressively removing the variant from the line\n- Clear animals can be used for breeding without risk of transmitting the trait

A negative result only rules out the SPH and DRX variants, not other curly-coat variants (Cornish rex, Selkirk rex, Ural rex) or other skin defects. The Sphynx's skin requires specific fold hygiene and sun protection. Differentiate the physiological seborrhoea of the Sphynx from infectious dermatitis. The presence of compound animals in the pedigree must be explicitly recorded.

1. Gandolfi B et al. 2010. The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71. Mamm Genome. PMID: 20953787
2. OMIA:001583-9685 / OMIA:001581-9685 (gen KRT71).