The commonalities across types of brain structural and functional abnormalities are also seen in the behavioral domain, where there is an intriguing suggestion of dosage effects on common domains of cognitive and behavioral abnormalities across the X chromosome SCAs. For example, individuals with Turner’s syndrome who have haploin-sufficiency of the X chromosome tend to have impaired visuospatial cognition in the presence of intact language capabilities [Bender et al., 1984a; Haberecht et al., 2001; Ross et al., 2006]. Conversely, as described earlier, the most common cognitive abnormality in either males or females with an extra X chromosome is delayed or impaired language development, whereas in XXY males visuospatial abilities are relatively preserved.
