While the results were mainly concordant across the studies, we found evidence of heterogeneity in the heritability for six metabolites; furthermore, 9 of the 54 COJO lead signals demonstrated significant heterogeneity between the studies, with discrepant effect size directions in the T1D cohort for the glycine GM2A association and for 5 secondary 3-aminoisobutyrate signals in the chromosome 5p13.2 locus. The gene discussed is GM2A; the disease is type 1 diabetes mellitus.