Gene mapping of familial amyotrophic lateral sclerosis

Abstract

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disorder characterized by gradual death of motor neurons in cerebral cortex, brain stem, and spinal cord. The pathogenetic mechanism remains unclear for the vast majority of cases. About 10% of ALS cases are familial (FALS). Cu/Zn superoxide dismutase (SOD1) gene accounts for about 10% of autosomal dominant FALS and the gene(s) responsible for the rest of ALS/ FALS remain(s) to be found. METHOD: We recruited a large Chinese kindred without SOD1 mutation for linkage analysis. Peripheral blood samples were collected and DNA were extracted from peripheral lymphocyte. We screened the family with ~ 400 polymorphic microsatellite markers. The genotyping data were subjected to model-based and model-free linkage analysis. RESULT: Using MLINK of LINKAGE (Ver 5.2) package, we found a maximum LOD score of 4.357, ?[m=f]=0.0 at a microsatellite marker located at distal long arm of chromosome 8. Multipoint analysis by GENEHUNTER (Ver 1.2) revealed a maximum multipoint LOD score of 3.909 and NPL score 9.209. Haplotype analyses revealed a critical region which spanned 10.18-cM on chromosome 8. CONCLUSION: We identified a 10.18-cM critical FALS region on chromosome 8. Further analyses using positional cloning and candidate gene approach are indicated to delineate the underlying genetic defect for FALS in this family.