Background17q12 microdeletion and microduplication syndromes present as overlapping, multisystem disorders. We assessed the disease phenotypes of individuals with 17q12 CNV in a population-based cohort.MethodsWe investigated 17q12 CNV using microarray data from 450 993 individuals in the UK Biobank and calculated disease status associations for diabetes, liver and renal function, neurological and psychiatric traits.ResultsWe identified 11 17q12 microdeletions and 106 microduplications. Microdeletions were strongly associated with diabetes (p=2×10−7) but microduplications were not. Estimated glomerular filtration rate (eGFR mL/min/1.73 m2) was consistently lower in individuals with microdeletions (p=3×10−12) and microduplications (p=6×10−25). Similarly, eGFR <60, including end-stage renal disease, was associated with microdeletions (p=2×10−9, p<0.003) and microduplications (p=1×10−9, p=0.009), respectively, highlighting sometimes substantially reduced renal function in each. Microduplications were associated with decreased fluid intelligence (p=3×10−4). SNP association analysis in the 17q12 region implicated changes toHNF1Bas causing decreased eGFR (NC_000017.11:g.37741642T>G, rs12601991, p=4×10−21) and diabetes (NC_000017.11:g.37741165C>T, rs7501939, p=6×10−17). A second locus within the region was also associated with fluid intelligence (NC_000017.11:g.36593168T>C, rs1005552, p=6×10−9) and decreased eGFR (NC_000017.11:g.36558947T>C, rs12150665, p=4×10–15).ConclusionWe demonstrate 17q12 microdeletions but not microduplications are associated with diabetes in a population-based cohort, likely caused byHNF1Bhaploinsufficiency. We show that both 17q12 microdeletions and microduplications are associated with renal disease, and multiple genes within the region likely contribute to renal and neurocognitive phenotypes.