| A congenital disorder of glycosylation with characteristics of severe or profound global developmental delay, early epileptic encephalopathy, muscular hypotonia, dysmorphic features (coarse facies, thick eyebrows, broad nasal bridge, thick lips, inverted nipples), variable ocular defects and brain morphological abnormalities on brain MRI (cerebral atrophy, thin corpus callosum). Caused by hemizygous or heterozygous mutation in the SLC35A2 gene on chromosome Xp11. |