Mutational analysis of the Cu/Zn superoxide dismutase gene in a Catalan ALS population: should all sporadic ALS cases also be screened for SOD1?
BACKGROUND
SOD1 gene mutations are the most common identified cause of ALS, accounting for approximately 20% of familial ALS cases and around 4% of sporadic ALS cases. However, the prevalence of SOD1 varies in different ethnic groups. No previous epidemiological studies have been carried out in Catalonia.


OBJECTIVE
To determine the prevalence of SOD1 gene mutations in a Catalan ALS population, and to analyze the genotype-phenotype relationship.


METHODS
30 different FALS pedigrees and 94 sporadic ALS patients were screened for SOD1 mutations using direct sequence analysis.


RESULTS
Five of the 30 FALS pedigrees (16.6%) carried a SOD1 mutant. The mutations identified in this group were G37R, D76V, S105L, I112M and N139H. Four SOD1 mutants (4.25%) were found in the sporadic ALS group (SALS). The overall frequency (FALS plus SALS) of SOD1 mutations in our series was 6.45%. In the SALS group, D90A was identified in a patient presenting the typical Scandinavian phenotype. A 53-year-old woman with no family history of ALS carried the N139H mutation. Two unrelated sporadic ALS cases carried the A140A SOD1 mutant.


CONCLUSIONS
The prevalence of the SOD1 mutation in FALS in Catalonia is similar to levels in other Mediterranean countries, but lower than those in reports studying the Belgian, Japanese, and Scottish populations. The prevalence of the SOD1 mutation was 4.25% in patients with no family history of ALS. These results may have significant repercussions on genetic counseling, and screening for the SOD1 mutation in sporadic ALS cases must therefore be considered.
Gamez
Josep
J
Department of Neurology, Hospital Universitari Vall d'Hebron, UAB, Passeig Vall d'Hebron, 119-135, 08035 Barcelona, Spain. 12784jgc@comb.es
Corbera-Bellalta
Marc
M
Nogales
Gisela
G
Raguer
Nuria
N
García-Arumí
Elena
E
Badia-Canto
Mercè
M
Lladó-Carbó
E
E
Alvarez-Sabín
José
J