A genome-wide association study identifies the GPM6A locus associated with age at onset in ALS

Amyotrophic lateral sclerosis (ALS) exhibits considerable clinical variability, such as differences in age at onset (AAO). Multiple factors, including genetic factors, may underlie this variability; however, the specific determinants remain unclear. To identify genes affecting AAO, we have conducted a genome-wide association study in Japanese patients with ALS (discovery cohort: n = 1808; replication cohort: n = 207). Here, we show that the minor A allele of rs113161727 at the ADAM29-GPM6A locus is associated with a younger AAO in the discovery cohort (effect, -4.27 years; p = 4.60 × 10^-8); this finding has been confirmed in the replication cohort (p = 0.0068) and meta-analysis (p = 1.08 × 10⁻⁹). Among 65 ALS patients with a SOD1 mutation, the AAO has been found to be 10.2 years younger in those with the A allele than in those without it (p = 0.002). This variant correlates with GPM6A upregulation in iPSC-derived motor neurons, suggesting GPM6A as a candidate AAO modifier. Overall, our study highlights the impact of genetic modifiers on ALS heterogeneity and provides a potential target for delaying disease onset.