HNF4A and diabetes mellitus: The penetrance of diabetes for RFX6 heterozygotes was substantially lower compared to pathogenic variants of HNF1A (70%, 95% CI 67–72 by the age of 25 years and 97%, 95% CI 96–98 by 50 years) and moderately lower than pathogenic variants of HNF4A (55%, 95% CI 50–60 by the age of 25 years and 91%, 95% CI 88–94 by 50 years) (Fig. 2).