It is noteworthy that almost all the site mutants, including the SOD CallA (40) (Table 1) which abolishes disulfide bond formation, and H46R/H48Q (50, 51) (Table 1) which demonstrates compromised Zn binding, can still present as dimers in a crystal, indicating that most of the ALS-associated mutants except the truncated ones such as SOD1 L126Z (52) (Table 1) can also form dimers in vivo, but these malformed SOD1 mutants should be unstable due to a dysfunctional disulfide bond and abnormal metal coordination (40). This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.