[Chromosomal aberrations in a subfertile cotton-top tamarin]

The present case report describes a female cotton-top tamarin which was taken over by the Zoo Basel to form a new breeding pair. The animal demonstrated increased marking behavior without any obvious medical reasons, dominant behavior, failure to become pregnant and its external genitals were ambiguous. A disorder of the sexual development (DSD) was suspected by the zoo veterinarians and in a first step, the chromosomes of the monkey were analyzed. Six cell lines with different karyotypes were observed. The two most frequent cell lines had a 46,XX or a 46,XY karyotype which are normal chromosome complements of female and male cotton-top tamarins, respectively. The other much less frequent cell lines showed numerical aberrations with and without a marker chromosome. Specific biological features of the Callitrichidae, such as natural twinning and genetic chimerism impeded the clarification of the pathogenesis and prevented a reliable prognosis on the fertility of the cotton-top tamarin.