SIMPLE AND DEFINED METHOD TO DETECT THE SOD-1 MUTANTS FROM PATIENTS WITH FAMILIAL AMYOTROPHIC-LATERAL-SCLEROSIS BY MASS-SPECTROMETRY

Mutations in Cu/Zn superoxide dismutase (SOD1) cause a subset of cases of familial amyotrophic lateral sclerosis (FALS). We established a si mple and defined method to detect the mutant SOD1 in erythrocytes by e lectrospray ionization mass spectrometry (ESIMS) using materials preci pitated with specific antiserum. Hemolysate was mixed with anti-SOD1 a ntiserum and the generated precipitate, which was soluble in the solve nt for MS analysis, was injected on to an LC column connected to an ES I-mass spectrometer. MS spectra of the reduced SOD1 prepared from norm al individuals showed ion peaks corresponding to free monomer SOD1. Th e spectra from FALS patients revealed doublet ion peaks corresponding to normal and mutant components. The ratios of mutant to normal SOD1 w ere about 1/2 in cases of (G37R) and (A4S), and about 0.15 in a case o f (H46R). This method provides for the rapid diagnosis using small amo unt of specimens, and will contribute to elucidate the pathomechanism of FALS through the quantification of SOD1 mutants in erythrocytes and in tissues of nervous systems. (C) 1998 Elsevier Science B.V. All rig hts reserved.