Background: Maturity-onset diabetes of the young type 5 (MODY5), a type of dominantly inherited diabetes mellitus and nephropathy, has been associated with mutations of the hepatocyte nuclear factor-1beta (HNF-1beta) gene, mostly generating truncated protein. Various phenotypes, including urogenital malformations, are related to HNF-1beta mutations.
Objective: To describe clinical and genetic findings in 13 patients with 8 novel HNF-1beta mutations.
Design: Multicenter, descriptive study.
Setting: 2 departments of diabetes, 1 department of internal medicine, and 1 department of nephrology.
Participants: 8 probands with diabetes diagnosed before 40 years of age and nondiabetic kidney disease who were selected independent of their family history of diabetes, and 5 offspring.
Measurements: Characteristics of diabetes, renal function and structure, genital tract abnormalities, pancreas structure, insulin secretion, exocrine pancreas function, and liver test results.
Results: All mutations, including 5 missense changes, were found in the DNA-binding domain. Cosegregation of the mutation and MODY5 phenotype was observed in 4 families. Occurrence of a de novo mutation was demonstrated in 2 families. Diabetes was present in 10 of 13 mutation carriers. It was clinically overt in 5 participants and found by screening at age 19 to 38 years in 5 participants. Pancreas atrophy was observed in 5 of 6 probands, and pancreas exocrine insufficiency was observed in 6 of 7 probands. Renal involvement, consisting of structural changes and slowly progressive renal failure, was recognized in 9 patients at 18 to 41 years of age. Dysplastic kidneys were found by ultrasonography in 3 fetuses who subsequently showed transient neonatal renal failure. Genital tract abnormalities were present in 5 probands and liver enzyme levels were abnormal in 11 of 13 patients.
Limitations: Since the study was small and not population-based, it could not estimate the prevalence of MODY5. Other phenotypes might be associated with HNF-1beta mutations.
Conclusions: Maturity-onset diabetes of the young type 5 encompasses a wide clinical spectrum. Analysis for mutations of HNF-1beta is warranted, even without a family history of diabetes, in nonobese patients with diabetes and slowly progressive nondiabetic nephropathy, particularly when pancreatic atrophy or genital abnormalities are present.