Clinical and genetic characterization of hereditary spastic paraplegia type 3A in Taiwan

Aim: To investigate the clinical and genetic features of hereditary spastic paraplegia (HSP) type 3A (SPG3A) in Taiwan. Methods: Mutational analysis of the ATL1 gene was performed for 274 unrelated Taiwanese HSP patients. The diagnosis of SPG3A was ascertained by the presence of a heterozygous pathogenic mutation in ATL1. The SPG3A patients received clinical, electrophysiological, and neuroimaging evaluations. Disease severity was assessed by using Spastic Paraplegia Rating Scale (SPRS) and disability score. Nineteen single nucleotide polymorphism (SNP) markers flanking ATL1 were genotyped for haplotype analysis of ATL1 p.R416C mutation. Results: Eighteen SPG3A patients from 11 families were identified. They typically presented a pure form HSP phenotype with disease onset ranging from age 1–68 years. Five heterozygous ATL1 mutations were identified, including p.R239C, p.V253I, p.Y336H, p.P342R and p.R416C. ATL1 p.R416C was the most common mutation and presented in five SPG3A pedigrees. Haplotype analyses demonstrated a shared haplotype in the 12 individuals carrying a p.R416C allele. Conclusion: SPG3A accounts for 4% (11 out of 274) of HSP in the Taiwanese cohort. Patents with the ATL1 p.R416C mutation in Taiwan may descend from a common ancestor. This study defines the clinical and genetic features of SPG3A in Taiwan and provides useful information for the diagnosis and management, especially in patients of Han Chinese descent.