[Clinical characteristics of SLC35A2 gene variants related congenital disorders of glycosylation typeⅡ].

To summarize the clinical characteristics of children with SLC35A2 gene variants related congenital disorders of glycosylation (SLC35A2-CDG), so as to improve the clinicians' understanding of this disease. Clinical data and gene detection results of 6 epilepsy children with SLC35A2 gene variants were treated in the Department of Pediatrics Peking University First Hospital from April 2019 to February 2020 were analyzed retrospectively. Six children with SLC35A2 gene variants were identified, including 1 male and 5 females. The onset age of seizure was 5.5 (ranged from 2 to 20) months. All 6 cases had epileptic spasms, 2 cases had focal seizures, 2 cases had myoclonic seizures, 1 case had tonic seizures and 1 case had generalized tonic-clonic seizures. All patients with SLC35A2 gene variants were diagnosed as infantile spasm with developmental delay. Four cases had microcephaly, 4 cases had micro skeletal abnormalities, 3 cases had hypotonia and facial dysmorphism, 2 cases had inverted nipples. Visual abnormality, auditory anomaly, congenital cardiac disease and feeding difficulty were observed in one patient. The electroencephalography showed hypsarrhythmia in 6 patients. The brain magnetic resonance imaging (MRI) showed thinning of corpus callosum in 3 patients, delayed myelination in 2 patients and normal brain MRI in 3 patients. There were 2 cases of in-frame deletions, 1 case of missense variant, 1 case of splice site variant, 1 case of 2.14 kb deletion in Xp11.23 (only containing SLC35A2 gene) and 1 case of SLC35A2 gene mosaicism. All 6 cases had de novo variants. The last follow-up age ranged from 18 to 52 months. One patient was seizure free and 5 patients still had frequent seizures after treatment with antiepileptic drugs. SLC35A2 gene variants are mainly de novo variants. The characteristics of patients with SLC35A2-CDG are seizures and developmental delay, infantile spasms are most common diagnosis, micro skeletal anomaly, microcephaly, hypotonia, facial dysmorphism were accompanied features.