SLC35A2-CDG: novel variants with two ends of the spectrum

Congenital disorders of glycosylation (CDGs) are rare inherited metabolic disorders associated with facial dysmorphism and in the majority of the patients, there is an important neurological impairment. Epilepsy was a main concern in rare forms of the disease. There are two groups of the disease: CDG-I results from the defects in glycan addition to the N-terminal and CDG-II occurs due to defects in the processing of protein bound glycans. SLC35A2-CDG is a rare form of CDG caused by mutations in the X-linked gene that encodes a UDP-Galactose transporter. The manifestations of the disease include seizures, failure to thrive, delayed myelination, and cerebral atrophy.

We describe herein a severe female child with intractable seizures, microcephaly, growth retardation, hypotonia, global developmental delay, facial dysmorphism, skeletal findings, cerebral/cerebellar atrophy, and thin corpus callosum, and a mildly affected male carrying a novel variant with seizures and mild global developmental delay who were found by whole exome sequencing (WES) for SLC35A2 mutations previously not reported.

Our findings expand the number of reported cases and add novel variants to the repertoire of SLC35A2-CDG.