[Japan Spastic Paraplegia Research Consortium (JASPAC)]

Japan Spastic Paraplegia Research Consortium (JASPAC), a nationwide clinical and genetic survey of patients with hereditary spastic paraplegia (HSP), was started in 2006 as a project of the Research Committee for Ataxic Diseases of the Ministry of Health, Labor, and Welfare, Japan. To date (April 4, 2014), 448 indexed patients with HSP have been registered from 46 prefectures in Japan. We are now performing molecular testing of the HSP patients using Sanger sequencing (SPG4, SPG11, SPG31, and ARSACS), comparative genomic hybridization (CGH) array (SPG1, 2, 3A, 4, 5, 6, 7, 8, 10, 11, 13, 15, 17, 20, 21, 31, 33, 39, 42, ABCD1, alsin, and ARSACS), and resequencing microarray (SPG1, 2, 3A, 4, 5, 6, 7, 8, 10, 11, 13, 17, 20, 21, 31, 33, and ABCD1). In 206 Japanese families with autosomal dominant HSP, SPG4 was the most common form, accounting for 38%, followed by SPG3A (5%), SPG31 (5%), SPG10 (2%), and SPG8 (1%). In 88 patients with autosomal recessive HSP, although SPG11 was the most common form, accounting for 6%, most showed significant genetic heterogeneity. The results of molecular testing will be applicable to patients in terms of improved positive diagnosis, follow-up, and genetic counseling. JASPAC will contribute to elucidating the molecular mechanisms underlying HSP, and will facilitate the development of better treatments for HSP.