XXY (Klinefelter syndrome): a pediatric quantitative brain magnetic resonance imaging case-control study.

Objective: An extra X chromosome in males (XXY), known as Klinefelter syndrome, is associated with characteristic physical, cognitive, and behavioral features of variable severity. The objective of this study was to examine possible neuroanatomical substrates of these cognitive and behavioral features during childhood and adolescence.

Methods: MRI brain scans were acquired for 42 XXY and 87 healthy XY age-matched control males.