SLC35A2 and Epileptic encephalopathy: Recent research discovered that mosaic variants of the SLC35A2 gene, which encodes the major Golgi-localized UGT that necessary for the glycosylation in both sphingolipid and protein, became the main cause of a rare genetic disease named congenital disorder of glycosylation (CDG) in which the majority of affected individuals suffer from varying degrees of neurological impairments, such as intellectual disabilities, dysmorphisms, and epileptic encephalopathies [18,19,20].