Mosaic variegated trisomy (42,XY/43,XY, + variable) in a male pigtail macaque monkey.

We identified an infant male pigtail macaque monkey with a bizarre karyotype which, to the best of our knowledge, has never before been reported in any species. Examination of 107 nuclei from cultured lymphocytes revealed 81 (75.7%) to be trisomic, but with the supernumerary chromosome varying from cell to cell, trisomy 16 being the most common. A small percentage (11.2%) of the nuclei had a normal 42,XY karyotype, and the balance, with the exception of one apparent monosomic (possibly a technical artifact), had multiple chromosome abnormalities. Examination of cultured skin fibroblasts revealed a similar karyotype. We called this karyotype a mosaic variegated trisomy. At birth, the animal had a cleft lip and palate and situs inversus of the heart. He subsequently showed significant developmental delay and apparent mental retardation. There were no clinical symptoms of hematological malignancy, which often have associated acquired chromosome abnormalities such as those described here. The animal survived for 2 yr and 8 mo under intensive care.