HNF1A and diabetes mellitus: We hypothesised that polygenic background contributes to this variability and that this influence differs from that of HNF1A-MODY.<h4>Methods</h4>To test whether polygenic background contributes to the GCK-MODY clinical phenotype, we analysed polygenic risk scores (PGS) for nine diabetes-related traits in 897 clinically referred individuals with GCK-MODY.