ABSTRACT
Sex Chromosome Aneuploidy Syndromes Approximately 35% of chromosome abnormalities in live-born infants involve sex chromosome aneuploidy. Affected individuals may have an additional X or Y chromosome or be lacking one. Patients with 47,XXX or 47,XYY karyotypes usually have no major birth defects or mental retardation, although the mean IQ may be 90 rather than 100. Patients with a 47,XXY karyotype (Klinefelter syndrome) have a tall, eunuchoid body habitus, small testes, and infertility. However, reproduction sometimes can be achieved through in vitro techniques with intracytoplasmic sperm injection. They are at increased risk for breast cancer, nongonadal germ cell tumors, and leg ulcers.
