Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease characterised by progressive loss of motor neurons. Approximately 5% of cases of ALS are familial, with the remaining being sporadic. Although the aetiology of sporadic ALS (SALS) is largely unknown, familial and epidemiological data indicate that genetic factors may contribute to its pathogenesis. To date, a number of modifier loci and associated genes have been implicated and several polymorphic variants have been proposed as risk factors for developing SALS.1 Despite this, no single gene has been definitively shown to cause SALS as attempts to replicate positive findings in different populations have often failed. For example, more recently, replication failed to associate vascular endothelial growth factor or angiogenin across populations with different genetic background, including an Italian population.2 Lack of replication and/or small effects of associated alleles are obvious problems in the understanding of a complex and genetically heterogeneous disorder such as SALS.

However, it has been demonstrated recently that the variant rs10260404 within the DPP6 gene is …