Prevalence of the mutation in cyclophilinB (PPIB), a causal candidate gene for HERDA, among Quarter Horses in France

Hereditary equine regional dermal asthenia (HERDA) in Quarter Horses is an inherited degenerative skin disease. Initially reported as hyperelastosis cutis, HERDA has a phenotype of hyperextensible, fragile skin, with secondary seromas, haematomas, ulcers and scarring. It primarily affects the dorsal aspect of the body. An autosomal recessive mode of inheritance is considered likely, with affected horses more at risk to produce affected offspring. A mutation in cyclophilinB (PPIB) as a novel, causal candidate gene for HERDA has been described, and verified as segregating with carriers and affected horses. Screening of control Quarter Horses in the USA has indicated a 3.5% carrier frequency. The prevalence of this mutation among Quarter Horses in France was determined to be 1.6%.