Since the criteria for evaluating variant molecular pathogenicity by functional assays, set by the ClinGen Monogenic Diabetes Expert panel and HNF4A specific AMCG/AMP guidelines, are directed towards loss-of-function variants, these guidelines are not applicable for interpretation of variants displaying assay specific gain-of-function (e.g. R85W and partly R85Q). Here, HNF4A is linked to diabetes mellitus.