[Follow-up and genetic study of 43 Chinese children with type Ⅰ Alexander disease]

Objective: To identify the clinical and genetic characteristics in 43 Chinese children diagnosed with type Ⅰ Alexander disease (AxD). Method: Forty-three type Ⅰ AxD cases identified by glial fibrillary acidic protein (GFAP) gene mutations in Peking University First Hospital from 2005 to 2016 were followed up. The data of medical history, physical examination and magnetic resonance imaging (MRI) were collected. All these patients were followed up in December 2010, Febury 2012, June 2014 and January 2016, respectively. Result: Forty-three patients were genetically confirmed as type I AxD and the median age at the last visit was 11.71 years (10.27, 13.15). The characteristic clinical manifestations of these type Ⅰ AxD patients were developmental delay (79%, 34/43), seizures (86%, 37/43), macrocephaly (the median percentile of head circumference is 90%), and paroxysmal deterioration (27%, 13/43). All the 43 patients' brain MRI satisfied typical MRI features proposed by van der Knaap. According to the analysis of the long-term follow-up, patients with type Ⅰ AxD began to have obvious regression in motor function after 7 years of age, and the social life ability was milally impaired 8(6, 10)scores at the last follow-up. Seventeen heterozygous missense mutations of GFAP were identified in 43 genetically confirmed patients, and 4 mutations were novel. The mutations in 41 patients (95%, 41/43) were de novo. Three hot spots of mutation in Chinese patients were found: p. Arg239(35%, 15/34), p. Arg79 (26%, 11/43) and p. R88 (16%, 7/43). Conclusion: The characteristic clinical manifestations of type Ⅰ AxD patients are developmental delay, seizures, macrocephaly and paroxysmal deterioration. Moreover, a few patients may present with brain stem symptoms, mental abnormalities, scoliosis or kyphosis. Patients with type Ⅰ AxD may show significant regression in motor function after 7 years of age.