This comprehensive guide to X and Y chromosome aneuploidy is written in lay language for affected individuals and their families, providing an authoritative volume that explains X and Y chromosome variations in clear and accurate terms. These surprisingly common genetic conditions, affecting 1 in 500 individuals, include Klinefelter syndrome, Trisomy X and 47,XYY. This guide provides a lifespan approach to the three trisomy conditions, as well as their less common variations involving 48 and 49 chromosomes. Readers are provided clear explanations of the genetics involved, diagnosis and disclosure issues, development from infancy through early adulthood, potential health and fertility concerns, and educational and psychosocial considerations. The text is illustrated with actual quotations from those who live with the disorders, and provides not only descriptions of potential concerns, but also strategies for successfully addressing the challenges that may develop. Written by an experienced social worker in the field of developmental disabilities, who is also the mother of a young adult with 47,XXY, the book is an invaluable resource for families as well as for the professionals who work with these children and adults. The material on which the book is based includes a survey of over 800 adults and families who live with sex chromosome aneuploidy, as well as the most recent professional articles available summarizing research into the genetic mechanism of the disorder, characteristics of the population of each condition, co-morbid medical issues, and current treatment recommendations. The guide dispels myths that have been associated with these poorly understood disorders, including their association with mental disability and criminal behavior. It provides families and persons facing the diagnosis of one or more extra X or Y chromosomes excellent reason to expect a fulfilling and rich life, as well as detailed and practical information to use in obtaining state-of-the-art medical care and appropriate educational and social services.