Follow-up study of 22 Chinese children with Alexander disease and analysis of parental origin of de novo GFAP mutations.

To delineate the phenotype and genotype in Chinese children with type I Alexander disease (AxD) and the parental origin of de novo glial fibrillary acidic protein (GFAP) mutations. Twenty-two children with clinically diagnosed type I AxD were followed up for 1.66-6.62 years. Allele-specific PCR was used for the analysis of parental origin of the allele harboring the de novo mutation. Phenotype of these patients were consistent with type I AxD described in other population, with developmental delay (motor delay in 81.82%, cognitive delay in 63.64%), macrocephaly (100%), seizures (95.45%), paroxysmal deterioration (27.27%) and typical brain magnetic resonance imaging (100%). Progression was slower than reported. At 8.55 years of age (5.29-13.25), all patients who underwent the second follow-up were alive. Eleven heterozygous missense mutations of GFAP were identified in 21 patients, with three novel mutations. Reported hot spot mutations, p.R79, p.R239 and p.R88, were also identified in Chinese patients. Mutations were de novo in all but one case. The mother of a proband was demonstrated to be a presymptomatic patient with type II AxD with a p.R79H mutation. Ninety percent of de novo mutations were on the paternal allele demonstrated by allele-specific PCR. This is the largest follow-up study on Chinese children with AxD. The phenotypes of these patients are consistent with reports in other populations. GFAP mutations were identified in 95.46% of Chinese children with clinically diagnosed type I AxD. Our data suggested a male germ-line transmission.