SLC35A2-CDG is a congenital disorder of glycosylation caused by mutations in the SLC35A2 gene encoding a Golgi-localized UDP-galactose transporter. This transporter plays an essential role in glycan synthesis by transporting UDP-galactose from the cytoplasm into the Golgi lumen. Its dysfunction leads to impaired galactose-containing glycans and various neurological symptoms, although the underlying mechanisms remain largely unknown. We identified a novel SLC35A2-CDG patient carrying a pathogenic variant (c.617_620del, p.(Gln206ArgfsTer45)) who exhibited neurological abnormalities including bilateral ventriculomegaly. To investigate the disease mechanism, we established the first Drosophila model of SLC35A2-CDG.