Cornish Rex — questions to ask before paying a deposit
A responsible breeder will have these readily available. Deflection is a red flag.
Neonatal isoerythrolysis risk (blood type B)Common in this breed
Cornish Rex is named by UC Davis VGL as one of the breeds with a high frequency of the blood type B allele. A type B queen mated to a type A or AB tom risks kittens developing neonatal isoerythrolysis after nursing colostrum containing anti-A antibodies. A 2022 screen found type B blood in 33.0% of 106 Cornish Rexes, about one in three.
Ask to see: AB blood typing test (UC Davis VGL and other labs). Both breeding partners should be blood-typed before pairing.
Feline AB Blood Type test -- notes Cornish Rex among breeds with high blood type B frequency, UC Davis Veterinary Genetics Laboratory (https://vgl.ucdavis.edu/species/cat) · Anderson et al. 2022, PLOS Genetics (Table 3, Cornish Rex row) (https://doi.org/10.1371/journal.pgen.1009804)
Progressive retinal atrophy (PRA rdAc, CEP290)can shorten life or cause chronic painCommon in this breed
An inherited, slowly progressive disease of the retina that ends in blindness. Affected kittens see normally at first; in affected Abyssinians the retina is already working less well by eight months, changes can be seen at the back of the eye at one to two years, and sight is impaired by five to six years. It is recessive, so a kitten is affected only if it inherits a copy from each parent. The mutation is common in the Cornish Rex: a 2022 screen of over 11,000 cats found 31 of 106 Cornish Rexes carrying it, roughly three in ten (29 with one copy and 2 with two copies); most of the Cornish Rexes screened came from Finland. A 2010 survey of North American cats found 1 carrier among 20 Cornish Rexes, and its authors name the Siamese as the likely source. No published study has examined the eyes of a Cornish Rex with two copies, so how the disease runs in this breed has not been described; in Siamese-group cats with two copies it looked like the Abyssinian disease.
Ask to see: UC Davis VGL PRA rdAc (CEP290) DNA test result, on both parents
Anderson et al. 2022, PLOS Genetics (Table 2 and S4 Table, Cornish Rex rows) (https://doi.org/10.1371/journal.pgen.1009804) · Menotti-Raymond et al. 2010, The Veterinary Journal (Table 1, Cornish rex row) (https://doi.org/10.1016/j.tvjl.2009.08.010) · Menotti-Raymond et al. 2007, Journal of Heredity (https://doi.org/10.1093/jhered/esm019) · OMIA — Retinal degeneration II (cat) (https://omia.org/OMIA001244/9685/)