The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71

Area of Science:

• Genetics
• Mammalian Biology
• Dermatology

Background:

• Hair is a defining characteristic of mammals, crucial for homeostasis and tissue integrity.
• Previous research linked Keratin 71 (KRT71) gene polymorphisms to curly or wavy hair phenotypes in dogs, mice, and rats.

Purpose of the Study:

• To investigate the genetic basis of hairless and curly coat mutations in domestic cats.
• To identify specific polymorphisms in the KRT71 gene associated with Sphynx and Devon Rex breeds.

Main Methods:

• Direct sequencing of the KRT71 gene's coding sequence and 3' UTR in cats with various pelage mutations.
• Genotyping of identified polymorphisms in approximately 200 domestic cats.
• Analysis of sequence alterations and their correlation with observed phenotypes.

Main Results:

• A splice site altering single nucleotide polymorphism (SNP) in KRT71 was identified as the hairless (hr) allele in Sphynx cats.
• A complex splice variation in KRT71 was identified as the curly (re) allele in Devon Rex cats.
• Genotyping confirmed a strong association between these KRT71 variants and the respective coat phenotypes, with Devon Rex cats being homozygous for the re allele and Sphynx cats predominantly homozygous for hr or compound heterozygous with re.

Conclusions:

• The identified KRT71 polymorphisms are the causative mutations for the hairless (Sphynx) and curly (Devon Rex) phenotypes in domestic cats.
• An allelic series for KRT71 is proposed: KRT71( + ) > KRT71( hr ) > KRT71( re ).
• No other causative mutations were found for eight different rexoid and hairless cat phenotypes examined in the study.