Influence of X chromosome and hormones on human brain development: A magnetic resonance imaging and proton magnetic resonance spectroscopy study of Turner syndrome

Background: Women with Turner syndrome (TS; 45,X) lack a normal second X chromosome, and many are prescibed exogenous sex and growth hormones (GH). Hence, the allow its an opportunity to investigate genetic and endocrine influences on brain development. Methods: We examined brain anatomy and metabolism in 27 adult monosomic TS women and 21 control subjects with volumetric magnetic resonance imaging and magnetic resonance spectroscopy. Results: In TS women, regional gray matter volume was significantly smaller in parieto-occipital cortex and caudate nucleus and larger in cerebellar hemispheres. White matter was reduced in the cerebellar hemispheres, parieto-occipital regions, and splenium of the corpus callosum but was increased in the temporal and orbitofrontal lobes and genui of corpus callosum. Women with TS bad a significantly lower parietal lobe concentration of N-acetyl aspartate, and higher hippocampal choline. Also, among women with TS, there were significant differences in regional gray matter volumes and/or neuronal integrity, depending upon. parental origin of X chromosome and oxandrolone and GH use. Conclusions. X chromosome monosomy, imprinting and neuroendocrine milieu modulate human brain development-perhaps in a regionally specific manner.