Aneuploidy of sex chromosomes in a tortoiseshell cat – case report

Cytogenetic analysis is an important step in the diagnosis of animals with a history of infertility or sterility. While chromosomal studies have been indicated for livestock species for years, the demand for such analyzes in companion animals has recently increased. The coat color in cats known as tortoiseshell presents predominance of black hair mixed with white and orange hair all over the body and, in the color pattern known as calico, these three colors are presented as independent spots with predominance of white hair. However, all of these patterns are limited to females due to sex-linked inheritance. Male tortoiseshell or calico cats occur rarely, due to the occurrence of chromosomal aberrations. This article reports the chromosomal analysis of a male cat with tortoiseshell pelage that presented an extra X chromosome (diploid chromosome set of 2n = 39,XXY), a condition which is similar to Klinefelter syndrome in humans.