Autistic disorder associated with an iso-dicentric Y chromosome.

The relationship between a fragile site on the X chromosome and autism has been well documented. The authors report a three-year-old child with partial duplication of the short arm of chromosome Y, who had an autistic disorder. He was microcephalic, but otherwise had a normal phenotype. There was a history of preterm birth and maternal diabetes. This is the sixth case of sex chromosome Y aneuploidy associated with autism, but the first with an isodicentric Y. In well-substantiated cases of autism, clinicians should now consider abnormalities of the Y as well as the X chromosome.