Abstract: Objective To summarize the clinical characteristics of ATP 1 A 3 gene associated paroxysmal diseases, and to explore clinical phenotype and genotype relationship. Methods Clinical data and genetic test results of four children with ATP 1 A 3 gene associated paroxysmal diseases recruited from September, 2018 to December, 2019 were retrospectively analyzed. Results Four male patients were recruited. The median age of onset was 5 months (ranged from 20 days to 9 months) . Clinical phenotypes of the four children were alternating hemiplegia of children (AHC), AHC with epilepsy, epilepsy, and CAPOS (cerebellar ataxia, areflexia, pes cavus, opticatrophy, and sensorineural hearing loss) syndrome respectively. The initial symptoms and clinical manifestations were different, but there was some overlap. All four children were found with heterozygous mutations in the ATP 1 A 3 gene, including three de novo and one maternal inherited missense mutation. Among which, c.2423 C>T, has not been reported, and c.2839 G>C, c.2401 G>A and c.2452 G>A are reported as pathogenic mutations. Conclusions ATP 1 A 3 gene mutations can cause different clinical phenotypes such as AHC, CAPOS syndrome and epilepsy. c.2423C>T, is a novel pathogenic mutation that has not been reported.

Key words: ATP 1 A 3 gene; CAPOS syndrome; alternating hemiplegia of child; epilepsy