A tortoiseshell male cat: chromosome analysis and histologic examination of the testis

Cytogenet Genome Res. 2014;142(2):107-11. doi: 10.1159/000356466. Epub 2013 Dec 6.


Tortoiseshell coat color is normally restricted to female cats due to X-linkage of the gene that encodes the orange coat color. Tortoiseshell male cats do, however, occur at a low frequency among tortoiseshell cats because of chromosome aberrations similar to the Klinefelter syndrome in man: the extra X chromosome of a 39,XXY karyotype introduces the possibility of an orange and a non-orange allele which produce the mixture of orange and non-orange coat spotting known as tortoiseshell. We analyzed the chromosome complement of a fibroblast culture and did histological examinations of testicular tissue from a tortoiseshell male cat referred to us. Chromosome analysis using RBA-banding consistently revealed a 39,XXY karyotype. Histological examinations of testis biopsies from this cat showed degeneration of the tubules, hyperplasia of the interstitial tissue, and complete loss of germ cells. Immunostaining using anti-vimentin and anti-VASA (DDX4) showed that only Sertoli cells and no germ cells were observed in the testicular tubules. As no sign of spermatogenesis was detected, we conclude that this is a classic case of a sterile, male tortoiseshell cat with a 39,XXY chromosome complement.

Publication types

  • Case Reports

MeSH terms

  • Animals
  • Cats / genetics*
  • Chromosome Aberrations / veterinary*
  • DEAD-box RNA Helicases / immunology
  • Germ Cells / cytology
  • Hair Color / genetics*
  • Karyotype
  • Klinefelter Syndrome / genetics
  • Klinefelter Syndrome / veterinary*
  • Male
  • Sertoli Cells / pathology
  • Spermatogenesis / genetics
  • Testis / pathology*
  • Vimentin / immunology


  • Vimentin
  • DEAD-box RNA Helicases