This is the first book on X and Y chromosomal disorders to address these common but rarely diagnosed conditions. This book seeks to present the latest in research and clinical care addressing neuroimaging, the interaction between hormones, brain development, and neurodevelopmental progression. This book will primarily focus on 47, XXY (Klinefelter syndrome, or KS), 47, XYY (Jacobs' syndrome), and 47, XXX (Triple X). More variant disorders such as 48, XXXX, 48, XXXY and 49, XXXXY will be discussed. Topics of interest include neurological functioning, neuroimaging, social language, and the evolving perspectives of these XY chromosomal disorders. The effects of testosterone supplementation in males with 47, XXY will also be examined.