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

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