HNF4A and diabetes mellitus: For example, previous studies had estimated the penetrance of HNF4A rs137853336 (chr20:43042354C>T, p.Arg114Trp) to be up to 75% by age 40 years from a large Maturity Onset Diabetes of the Young cohort, but data from the UK Biobank estimated penetrance to be <10% [19].