RESUMO
INTRODUCTION: Mutations in the gene encoding the free radical scavenging enzyme CuZn-superoxide dismutase have been associated with amyotrophic lateral sclerosis (ALS). Ninety-eight mutations have been found worldwide in patients with ALS, all but one showing a dominant pattern of inheritance. The exception is the D90A mutation which in Finland, northern Norway and northern Sweden exists with an allele frequency of 1-2.5% and is in these regions associated with ALS inherited as a recessive trait. METHODS AND RESULTS: In this study we searched for the D90A CuZn-SOD mutation in different ethnic populations of the Russian Federation and found the D90A mutation not only in locations close to the Scandinavian peninsula but also in remote populations in Asia. CONCLUSION: The finding makes the D90A mutation the most prevalent CuZn-SOD mutation globally and has implications for interpreting the recent reports of D90A-heterozygous ALS patients in North America and Europe.