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More than 140 different mutations have been reported in the Cu/Zn superoxide dismutase-1 (SOD1) gene in patients with amyotrophic lateral sclerosis (ALS), some occurring as founder mutations. Occasionally, specific mutations are associated with a particular phenotype. We evaluated a possible genotype-phenotype correlation and looked for a founder effect in nine patients from six unrelated families with ALS, all carrying the G41S mutation, originating from north-west Tuscany in central Italy. Mutational analysis of the SOD1 gene was carried out by direct sequencing. A haplotype study was carried out using eight polymorphic markers flanking the SOD1 gene. The clinical pattern of the nine familial ALS (FALS) patients was characterized by spinal onset with early upper and lower motor neuron involvement, appearance of bulbar signs within one year, and death a few months later. Mean age at onset was 49.3 years and mean duration of disease was 0.9 years. Genotyping revealed a common haplotype for the G41S allele. We provide the first evidence that the G41S mutation in Italy originates from a common founder. In addition, our findings strengthen the data reported previously and indicate that the G41S mutation is consistently associated with a uniform and dramatic, fast-progressing phenotype.

Among the 140 Cu/Zn superoxide dismutase-1 (SOD1) gene mutations associated with ALS, only D90A, the most prevalent mutation in Europe, has been clearly shown to cause recessive and dominant ALS. Here we first describe two, apparently sporadic, Italian ALS patients heterozygous for the D90A mutation. One patient experienced early sensory involvement, confirmed by nerve biopsy. We review sensory symptoms in SOD1 ALS and discuss its possible origin in D90A heterozygous patients.

The Aspartate-90-Alanine (D90A) mutation on SOD-1 gene, the only known change causing recessive familial amyotrophic lateral sclerosis (FALS), is associated with a uniform phenotype characterized by slowly ascending paresis and long survival. Originally reported in Scandinavian cases, it has also been detected in patients from other countries. A common haplotype, probably of Scandinavian origin, has been demonstrated in D90A recessive pedigrees. In this study we screened the SOD-1 gene for the D90A mutation in 56 Italian patients from north-west Tuscany with sporadic ALS in order to evaluate the occurrence of this mutation and its genotype-phenotype correlation in Italy. We found the homozygous D90A mutation in one patient (1.8%), harboring the classical phenotype related to this mutation. No other mutations were detected in any of the five SOD-1 exons in our group. Our results confirm that recessive D90A mutation is present in Italy and it is associated with the phenotype already described A screening for that mutation, easily made by RFLP, should be made in sporadic ALS patients, especially where clinical investigation indicates its presence.