Volumetric Magnetic Resonance Imaging Study Of The Brain In Subjects With Sex Chromosome Aneuploidies

Objectives-Cognitive impairment has been reported in people with sex chromosome aneuploides (SCAs) and it has been proposed that the presence of an extra sex chromosome may have an adverse effect on neurodevelopment. This study examines the hypothesis with structural MRI of the brain.Methods-Thirty two subjects with SCA (XXX (n=12), XYY (n=10), and XXY (n=10)) from a birth cohort study were matched groupwise for age, parental social class, and height with normal controls (13 female, 26 male). Brain MRI, measurements of IQ, and a structured psychiatric interview were performed.Results-The XXX females and XXY males had significantly smaller whole brain volumes than controls of the same phenotypic sex (p=0.003 and p less than or equal to 0.05 respectively). The bilaterally enlarged lateral ventricles (p less than or equal to 0.05). No significant differences were found between the XYY group and controls. IQ scores in all SCA groups were lower than in the control groups.Conclusions-The main result of reduced brain volumes in XXX and SSP subjects, but not in XYY subjects, indicates that the presence of a supernumerary X chromosome has a demonstrable effect on brain development.