Disorder of sex development in a cat with chromosome mosaicism 37,X/38,X,r(Y)

An 18-month-old European shorthair cat was subjected to genetic studies due to ambiguous external genitalia (underdeveloped both penis and scrotum). Further anatomic and histopathological studies revealed the presence of abdominal, atrophic testes and uterus. Cytogenetic analysis showed two cell lines, one with X monosomy-37,X [90% of the analysed metaphase spreads], and other line had 38 chromosomes with normal X chromosome and abnormally small Y-derived chromosome-38,X,der(Y) [10%]. Further fluorescence in situ hybridization study with telomeric probe revealed a ring structure of the der(Y). Eight Y chromosome-specific genes, SRY, TETY1, TETY2, CUL4BY, CYORF15, HSFY, FLJ36031Y and ZFY, were detected. We conclude that the described abnormality of the reproductive system, leading to sterility, was caused by a very rare type of chromosomal mosaicism-37,X/38,X,r(Y).