Other data on brain development in 47,XYY subjects had been limited to case reports. Abnormalities were reported on ultrasound examination of two 47,XYY fetuses. One was done as part of a workup of an abnormal midgestational serum marker screening test, and identified agenesis of the corpus callosum. The second was evaluated as part of evaluation of increased nuchal translucency; increased size of the cisterna magna and cerebellar vermal deficiencies were seen, consistent with Dandy-Walker syndrome [Maymon et al., 2002]. A separate report of a postmortem examination of a 47,XXY infant found abnormal gyral formation in the frontal lobes [Austin and Sparkes, 1980].
