Dominant blue eyes in Maine Coon cats: New PAX3 variant and updated phenotypic data

Abstract

Feline minimal white spotting associated with blue eyes, a trait called DBE by breeders for dominant blue eyes, was selected recently to create various lineages of cats and the Celestial breed. Previously, we identified three Paired Box 3 (PAX3) gene variants that account for some of the DBE phenotypes in cats, confirming different founding effects. Using a candidate gene approach, we identified a fourth PAX3 variant in a purebred Maine Coon lineage segregating for DBE and lacking a previously identified genomic variant. Segregation of the variant was consistent with the dominant inheritance pattern observed in this DBE lineage called the "Agostino line" by breeders. This PAX3:c.160del frameshift variant, located in PAX3 exon 2, was predicted to produce a truncated PAX3 protein: PAX3:p.(His54ThrTer108) that would lack 78% of the amino acids of the wildtype protein. All 13 DBE Maine Coon cats from the line were heterozygous for the variant, that was absent in all non-DBE Maine Coon cats from the line and in all control cat genomes (n > 300). We propose that this PAX3:c.160del variant represents the DBE^AGO (Agostino Dominant Blue Eyes) allele in the domestic cat. In addition, we improved the phenotypic description of DBE in Maine Coon cats, highlighting the need to reassess the prevalence of deafness and revealing the existence of latent cats in the previously described DBE^RE (Rociri Elvis Dominant Blue Eyes) Maine Coon lineage.

Keywords: BAER; DBE; coat colour; deafness; eye; feline; fur; white spotting.

FIGURE 1

Dominant blue eyes (DBE) in the Agostino Maine Coon line. (a) DBE phenotype in a Maine Coon male from the Agostino line. Note the bicolour phenotype due to the W ^S allele and the two blue eyes (b) DBE phenotype in a Maine Coon female from the Agostino line. Note the discrete white spotting and the two blue eyes. (c) Partial pedigree‐tree of the studied family from the Agostino line segregating DBE. Circles represent females, squares represent males, diamonds represent kittens of unknown sex. DBE cats with heterochromia or two blue eyes are depicted with fully filled symbols. Cats showing bicolour, harlequin, or van phenotypes (white areas representing 25%–50%, 50%–75%, and >75% of the coat respectively, due to the presence of the W ^S allele) are surrounded in pink. Genotypes for the PAX3:C.160del variant are shown (+/+: wild‐type; +/del: heterozygous for the deletion). The star indicates the female that is not part of the family studied but is directly related to it. The green ellipse indicates the male shown on picture (a), the yellow circle indicates the female shown in picture (b). This pedigree‐tree was concordant with an autosomal dominant inheritance for DBE.