Partial duplication of the short arm of chromosome 10. Karyotype: 46,XX,dup(10p)(pter to p12::p12::p12 to qter).

A 21-year-old mentally retarded female with 10p12 trisomy is reported. She presented a slight craniofacial dysmorphism very similar to that found in the full 10p-trisomy syndrome. Other features usually found in full 10p trisomy, however, such as failure to thrive and internal malformations, were absent.