Identifying hepatic nuclear factor 1alpha mutations in children and young adults with a clinical diagnosis of type 1 diabetes.

OBJECTIVE: HNF-1alpha gene mutations (MODY3) present with marked hyperglycemia in lean young adults and may, therefore, be mistaken for type 1 diabetes, with implications for individual treatment and risk of diabetes in other family members. We examined the prevalence of HNF-1alpha mutations in families with three generations of diabetes identified in a population-based study of childhood diabetes, representing a subpopulation in which misclassification was likely. RESEARCH DESIGN AND METHODS: In a study population of 1,470 families, 36 families (2.4%) with three affected generations were identified. In the 18 families in whom DNA samples were available, islet autoantibody testing, HLA class II genotyping, and HNF-1alpha sequencing were performed. RESULTS: At least one islet autoantibody was found in 13 of 14 probands, and diabetes-associated HLA class II haplotypes were found in 17 of 18. One proband, who had no islet autoantibodies and was homozygous for the protective HLA haplotype DRB1*02-DQB1*0602, had a novel HNF-1alpha heterozygous nonsense mutation (R54X). This mutation cosegregated with diabetes in the family. The proband, his brother, mother, and maternal grandmother were diagnosed with type 1 diabetes aged 14-18 years and treated with insulin (0.39-0.74 units/kg) from diagnosis. The mother has since been successfully transferred to sulfonylurea treatment. CONCLUSIONS: Family history alone is of limited value in identification of individuals with HNF-1alpha mutations, and we propose a stepwise approach that restricts sequencing of the HNF-1alpha gene to those with a family history of diabetes who also test negative for islet autoantibodies.

Hepatocyte nuclear factor-1beta: a new kindred with renal cysts and diabetes and gene expression in normal human development.

The hepatocyte nuclear factor-1beta (HNF-1beta) transcription factor controls endoderm development. Human mutations cause early-onset diabetes mellitus and have recently been associated with dysplastic, hypoplastic, and glomerulocystic kidneys. A new kindred with this "renal cysts and diabetes" syndrome is described, and nephrogenic HNF-1beta expression is defined. The proband had congenital cystic kidneys: over the next 12 yr, his renal function was impaired, but he was normoglycemic. His mother developed diabetes during pregnancy: renal ultrasonography at age 24 yr was normal, but she subsequently developed cysts. Both subjects have a heterozygous frameshift mutation in HNF-1beta that results from a 1-bp insertion in exon 5 (Y352fsinsA). When reverse-transcription PCR and in situ hybridization were used, HNF-1beta mRNA was detected in normal human metanephroi, with the highest levels of transcripts localized to fetal medullary and cortical collecting ducts and low levels of expression in nephrogenic cortex mesenchyme, primitive nephron tubules, and immature glomeruli. These results constitute the first demonstration of HNF-1beta expression during human nephrogenesis and emphasize a disease spectrum associated with HNF-1beta mutation.

Solitary functioning kidney and diverse genital tract malformations associated with hepatocyte nuclear factor-1beta mutations.

BACKGROUND: Renal tract malformations are, on occasion, associated with uterine malformations. The transcription factor hepatocyte nuclear factor (HNF)-1beta is expressed from the earliest stages of development of the Wolffian duct, the mesonephros and metanephros, and the Müllerian ducts in the mouse. In adult mice HNF-1beta is expressed in the kidney tubules, collecting ducts, and in the oviducts and uterus in the female (Müllerian duct derivatives) and in the epididymis, vas deferens and seminal vesicles (Wolffian duct derivatives) in the male. HNF-1beta mutations have been reported in two families where affected members have renal abnormalities, female genital tract malformations and early-onset diabetes. Renal and uterine abnormalities have not been described in families without early-onset diabetes. METHODS: We sequenced the HNF-1beta gene in nine subjects with renal abnormalities and a personal or family history of female genital tract malformations, but no history of diabetes. RESULTS: Two families were identified with novel HNF-1beta mutations: a missense mutation in exon 2 with conversion of serine to proline at codon 151 (S151P) and a frameshift mutation in exon 3 with a 1 base pair deletion at codon 243 (Q243fsdelC). The S151P mutation proband has cystic kidneys and uterus didelphys. Her affected second son has renal cysts and hypospadias. The Q243fsdelC proband has a single functioning kidney and her two children have renal dysplasia. Histology in one child shows cystic dysplasia with a lack of glomeruli. The proband's sister is a mutation carrier and has a bicornuate uterus. Diabetes is not a feature in either family. CONCLUSIONS: This study confirms an association between HNF-1beta mutations and renal and Müllerian anomalies. The hypospadias may be coincidental. This study describes the first HNF-1beta mutations that are associated with a single functioning kidney and the absence of diabetes. This study further reinforces the variability of the renal and non-renal phenotypes associated with HNF-1beta mutations.