Objective: To analyze the ATP1A3 mutations in patients with alternating hemiplegia of childhood (AHC) and recognize its value in diagnosing atypical cases.
Method: Data of all AHC patients seen at Peking University First Hospital from August 2005 to November 2014 were prospectively collected. Clinical information of the AHC patients and their family members were collected and analyzed. Genomic DNAs were extracted from their peripheral blood. Mutations in ATP1A3 were screened by Sanger sequencing after PCR.
Result: A total of 78 AHC patients were recruited, including 50 males and 28 females. Only three patients had family history of AHC. The first family case had affected mother with AHC; the second family case was the older one of a monozygotic male twins with AHC but their parents were normal; the third family case had a sister with AHC but their parents were normal. The age of onset ranged from six hours to eight years and six months (median: 4 months). According to the Aicardi's clinical diagnostic criteria, 72 patients were considered as typical AHC cases and the other six patients were considered as atypical AHC cases for their age of onset was older than 18 months. Twenty-seven different missense ATP1A3 mutations were detected in 71 (91.0%, 71/78) patients with AHC, including 66 typical and 5 atypical cases. 11 novel ATP1A3 mutations were first reported. ATP1A3 mutations were identified in the three AHC cases with family history. Parental analysis verified that the ATP1A3 mutation of 63 patients (95.5%, 63/66) were de novo origin except lack of five unavailable maternal or paternal genomic DNA. Mutation D801N was found in 20 cases (28.2%), and E815K in 12 cases (16.9%). In the six atypical AHC patients, ATP1A3 mutations were detected in five of them.
Conclusion: ATP1A3 was the major causative gene of AHC, and mutations were identified as de novo mostly. ATP1A3 mutations in AHC had mutational hotspot, and the most common mutations were D801N and E815K. ATP1A3 mutation screening is helpful for the genetic and definite diagnosis of the atypical AHC cases.