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High-resolution electrospray ionization Fourier transform mass spectrometry with infrared multiphoton dissociation of glucokinase from Bacillus Stearothermophilus.

Glucokinase (GK, EC 2.7.1.2), a member of the enzyme family of hexokinases, has been shown to be linked to maturity-onset diabetes of the young type II (MODY-2). Although nucleotide and amino acid sequence information are available for the human varieties, they are not known for the variety from Bacillus stearothermophilus, which is often used in protein binding studies. Here, a combination of electrospray Fourier transform mass spectrometry (FTMS) and infrared multiphoton dissociation (IRMPD) is used to obtain accurate molecular weight and preliminary amino acid sequence information for the protein. Electrospray FTMS provides evidence of a solution phase dimer. In addition, dithiothreitol reduction shows no shift in high-resolution isotopic distributions, indicating a probable absence of disulfide bonds in the protein. The partial sequence information obtained from IRMPD could be the basis for creating a DNA probe for the protein.

Fourier Analysis↗

Genetic variants of hepatocyte nuclear factor-1beta in Chinese young-onset diabetic patients with nephropathy.

In Hong Kong, the prevalence of diabetes is estimated to be 2% in the young population. In the diabetic population, 30% of patients have diagnosis before the age of 40 years. Besides, 30% of young diabetic patients have varying degrees of albuminuria. Mutations in the gene encoding the hepatocyte nuclear factor (HNF)-1beta are associated with a subtype of maturity-onset diabetes of the young (MODY 5) characterized by urogenital abnormalities. We examined 74 unrelated Chinese subjects with young-onset diabetes complicated by nephropathy for variants in this gene. The HNF-1beta gene was screened by direct sequencing and the functional properties of wild-type and mutant proteins were analyzed by transactivation analysis.A novel variant in exon 3 (E260D) was found in one patient. Extended family analysis revealed four other siblings carrying this variant. One subject had diabetes and another had impaired glucose tolerance. Another sibling had microalbuminuria but normal glucose tolerance. Transfection studies showed insignificant differences in transactivation ability between wild-type and mutated HNF-1beta. A silent polymorphism Q378Q was identified in another unrelated subject. These results suggest genetic variants in HNF-1beta are not a common cause of young-onset diabetes or diabetic nephropathy in Chinese, but may modify disease manifestation and progression. Other potential candidate genes should be looked for to account for the high prevalence of young-onset diabetes and nephropathy in this population.

Adolescent↗

In silico searching of human and mouse genome data identifies known and unknown HNF1 binding sites upstream of beta-cell genes.

HNF1-alpha is a transcription factor present in beta-cells. Mutations in the HNF1-alpha gene cause maturity-onset diabetes of the young (MODY), but the exact mechanism is not known. Several studies have highlighted genes down-regulated in beta-cells lacking this gene, but it is not clear if these are directly regulated by HNF1-alpha. To better understand this, we used human and mouse genome data to examine 29 genes expressed in the beta-cell. Using an in silico approach (with software available at www.BindGene.org) we examined 2kb upstream of each gene for possible HNF1 binding sequences. In five genes we also examined 100kb upstream of each gene, but only the portions strongly conserved between humans and mice. We identified nine putative HNF1 binding sites upstream of seven genes (p<0.1 and good alignment between species or p<0.05). Six of these nine sites had some experimental corroboratory evidence and included the recently identified sites 6 and 45kb upstream of HNF4-alpha. Three novel sites were identified. These were 92bp upstream of SLC3A1, 52bp upstream of PCBD (DCOH), and 42202bp upstream of TCF2(HNF1-beta). In conclusion, our computer search identified some known HNF1 sites, and suggested three novel sites indicating these genes are very likely to be directly activated by HNF1. This should help in designing experiments to discover the mechanisms of beta-cell dysfunction due to HNF1 disruption.

Animals↗

Classification of diabetes in young adults: new concepts for an old disease.

As clinicians, we are faced to difficult situations in young diabetic patients. The prevalence of type 2 diabetes increases in these patients due to a rising incidence of obesity. We present two clinical observations which both illustrate the insufficiencies of the present classifications. Modern tools are now available for diagnosis such as anti-GAD65 and IA-2 antibodies, genetic tools to investigate for specific mutations, but quantitative means of beta cell mass are lacking. Clinical examination is still accurate to identify type 1 or type 2 diabetes, MODY and mitochondrial diabetes. Weight curve, lesions of acanthosis nigricans, criteria of metabolic syndrome, history of diabetes are critical factors. This problematic has important consequences in our daily practice: the right choice for rapid and good metabolic control.

Adult↗

Energetics of sequence-specific protein-DNA association: binding of integrase Tn916 to its target DNA.

The DNA binding domain of the transposon Tn916 integrase (INT-DBD) binds to its DNA target site by positioning the face of a three-stranded antiparallel beta-sheet within the major groove. Binding of INT-DBD to a 13 base pair duplex DNA target site was studied by isothermal titration calorimetry, differential scanning calorimetry, thermal melting followed by circular dichroism spectroscopy, and fluorescence spectroscopy. The observed heat capacity change accompanying the association reaction (DeltaC(p)) is temperature-dependent, decreasing from -1.4 kJ K(-1) mol(-1) at 4 degrees C to -2.9 kJ K(-1) mol(-1) at 30 degrees C. The reason is that the partial molar heat capacities of the free protein, the free DNA duplex, and the protein-DNA complex are not changing in parallel when the temperature increases and that thermal motions of the protein and the DNA are restricted in the complex. After correction for this effect, DeltaC(p) is -1.8 kJ K(-1) mol(-1) and temperature-independent. However, this value is still higher than DeltaC(p) of -1.2 kJ K(-1) mol(-1) estimated by semiempirical methods from dehydration of surface area buried at the complex interface. We propose that the discrepancy between the measured and the structure-based prediction of binding energetics is caused by incomplete dehydration of polar groups in the complex. In support, we identify cavities at the interface that are large enough to accommodate approximately 10 water molecules. Our results highlight the difficulties of structure-based prediction of DeltaC(p) (and other thermodynamic parameters) and emphasize how important it is to consider changes of thermal motions and soft vibrational modi in protein-DNA association reactions. This requires not only a detailed investigation of the energetics of the complex but also of the folding thermodynamics of the protein and the DNA alone, which are described in the accompanying paper [Milev et al. (2003) Biochemistry 42, 3492-3502].

Base Sequence↗

Energetics of sequence-specific protein-DNA association: conformational stability of the DNA binding domain of integrase Tn916 and its cognate DNA duplex.

Sequence-specific DNA recognition by bacterial integrase Tn916 involves structural rearrangements of both the protein and the DNA duplex. Energetic contributions from changes of conformation, thermal motions and soft vibrational modi of the protein, the DNA, and the complex significantly influence the energetic profile of protein-DNA association. Understanding the energetics of such a complicated system requires not only a detailed calorimetric investigation of the association reaction but also of the components in isolation. Here we report on the conformational stability of the integrase Tn916 DNA binding domain and its cognate 13 base pair target DNA duplex. Using a combination of temperature and denaturant induced unfolding experiments, we find that the 74-residue DNA binding domain is compact and unfolds cooperatively with only small deviation from two-state behavior. Scanning calorimetry reveals an increase of the heat capacity of the native protein attributable to increased thermal fluctuations. From the combined calorimetric and spectroscopic experiments, the parameters of protein unfolding are T(m) = 43.8 +/- 0.3 degrees C, DeltaH(m) = 255 +/- 18 kJ mol(-1), DeltaS(m) = 0.80 +/- 0.06 kJ mol(-1), and DeltaC(p) = 5.0 +/- 0.8 kJ K(-1) mol(-1). The DNA target duplex displays a thermodynamic signature typical of short oligonucleotide duplexes: significant heat absorption due to end fraying and twisting precedes cooperative unfolding and dissociation. The parameters for DNA unfolding and dissociation are DeltaH(m) = 335 +/- 4 kJ mol(-1) and DeltaC(p) = 2.7 +/- 0.9 kJ K(-(1) mol(-1). The results reported here have been instrumental in interpreting the thermodynamic features of the association reaction of the integrase with its 13 base pair target DNA duplex reported in the accompanying paper [Milev et al. (2003) Biochemistry 42, 3481-3491].

Base Sequence↗

Genetic determinants of type 2 diabetes mellitus.

Type 2 diabetes refers to a group of disparate metabolic diseases, which are typically characterized by insulin resistance in peripheral tissues, together with impaired insulin secretion from pancreatic beta-cells. The complexity of type 2 diabetes is related to factors such as genetic heterogeneity, interactions between genes, and the modulating role played by the environment. Recent progress has included defining the molecular basis of monogenic forms of type 2 diabetes, such as familial partial lipodystrophy and the subtypes of maturity-onset diabetes of the young (MODY), and also the identification of chromosomal regions that may harbor type 2 diabetes susceptibility genes. Many common variants in functional and positional candidate genes, including ADRB3, PPARG, ENPP1, and CAPN10, have also been studied for their possible role as determinants of type 2 diabetes, with varying levels of agreement between studies. The availability of a relatively complete sequence of the human genome will increase the amount of genetic information that can be used to evaluate hypotheses for the genetic basis of type 2 diabetes. To make sense of human type 2 diabetes in the post-genomic era, it is essential to have well-defined phenotypes in addition to sufficient numbers of individuals with the appropriate pedigree structure from families and/or communities.

Animals↗

The gene MAPK8IP1, encoding islet-brain-1, is a candidate for type 2 diabetes.

Type 2 diabetes is a polygenic and genetically heterogeneous disease . The age of onset of the disease is usually late and environmental factors may be required to induce the complete diabetic phenotype. Susceptibility genes for diabetes have not yet been identified. Islet-brain-1 (IB1, encoded by MAPK8IP1), a novel DNA-binding transactivator of the glucose transporter GLUT2 (encoded by SLC2A2), is the homologue of the c-Jun amino-terminal kinase-interacting protein-1 (JIP-1; refs 2-5). We evaluated the role of IBi in beta-cells by expression of a MAPK8IP1 antisense RNA in a stable insulinoma beta-cell line. A 38% decrease in IB1 protein content resulted in a 49% and a 41% reduction in SLC2A2 and INS (encoding insulin) mRNA expression, respectively. In addition, we detected MAPK8IP1 transcripts and IBi protein in human pancreatic islets. These data establish MAPK8IP1 as a candidate gene for human diabetes. Sibpair analyses performed on i49 multiplex French families with type 2 diabetes excluded MAPK8IP1 as a major diabetogenic locus. We did, however, identify in one family a missense mutation located in the coding region of MAPK8IP1 (559N) that segregated with diabetes. In vitro, this mutation was associated with an inability of IB1 to prevent apoptosis induced by MAPK/ERK kinase kinase 1 (MEKK1) and a reduced ability to counteract the inhibitory action of the activated c-JUN amino-terminal kinase (JNK) pathway on INS transcriptional activity. Identification of this novel non-maturity onset diabetes of the young (MODY) form of diabetes demonstrates that IB1 is a key regulator of 3-cell function.

Adaptor Proteins, Signal Transducing↗

TIF1gamma, a novel member of the transcriptional intermediary factor 1 family.

We report the cloning and characterization of a novel member of the Transcriptional Intermediary Factor 1 (TIF1) gene family, human TIF1gamma. Similar to TIF1alpha and TIF1beta, the structure of TIF1beta is characterized by multiple domains: RING finger, B boxes, Coiled coil, PHD/TTC, and bromodomain. Although structurally related to TIF1alpha and TIF1beta, TIF1gamma presents several functional differences. In contrast to TIF1alpha, but like TIF1beta, TIF1 does not interact with nuclear receptors in yeast two-hybrid or GST pull-down assays and does not interfere with retinoic acid response in transfected mammalian cells. Whereas TIF1alpha and TIF1beta were previously found to interact with the KRAB silencing domain of KOX1 and with the HP1alpha, MODI (HP1beta) and MOD2 (HP1gamma) heterochromatinic proteins, suggesting that they may participate in a complex involved in heterochromatin-induced gene repression, TIF1gamma does not interact with either the KRAB domain of KOX1 or the HP1 proteins. Nevertheless, TIF1gamma, like TIF1alpha and TIF1beta, exhibits a strong silencing activity when tethered to a promoter. Since deletion of a novel motif unique to the three TIF1 proteins, called TIF1 signature sequence (TSS), abrogates transcriptional repression by TIF1gamma, this motif likely participates in TIF1 dependent repression.

Amino Acid Sequence↗

Spectroscopic and binding studies on the stereoselective interaction of tyrosine with horseradish peroxidase and lactoperoxidase.

The interaction of a series of derivatives of tyrosine with horseradish peroxidase (HRP) and lactoperoxidase (LPO) was studied by using optical difference spectroscopy, c.d. and proton n.m.r. spectroscopy in order to reveal differences in the mode of binding of L-tyrosine and D-tyrosine, which are substrates of but react at different rates with the two peroxidases, to HRP and LPO. All the donor molecules form 1:1 complexes with HRP and LPO, but they display a range of affinities for the enzymes. Whereas D-tyrosine binds to HRP more strongly than does L-tyrosine, the opposite holds for the binding to LPO. The distances of the protons of bound tyrosine molecules from the haem iron atoms of HRP and LPO indicate that the site of binding of these substrates is the same as that of simple phenols. This involves the interaction of the phenol nucleus with a protein tyrosine residue [Sakurada, Takahashi & Hosoya (1986) J. Biol. Chem. 261, 9657-9662; Modi, Behere & Mitra (1989) Biochim. Biophys. Acta 996, 214-225]. However, for the present substrates the additional interaction of the carboxylate group with a protein residue (probably an arginine residue) provides further stabilization for the adducts HRP-D-tyrosine and LPO-L-tyrosine with respect to the corresponding complexes with the opposite enantiomers. The differences in the mode of binding of L-tyrosine and D-tyrosine to HRP and LPO is thus determined by the fact that the spatial arrangement of the interacting protein residues can recognize the chirality of the C(alpha)-CO2- and C(beta)-C6H4OH attachment bonds of the substrates.

Animals↗

Mutation analysis of the human adipocyte-specific apM-1 gene.

BACKGROUND: The aim of this study was to analyse the human adipocyte-specific apM-1 gene for sequence variations. METHODS: Sequence analysis was performed in 344 randomly chosen blood samples using a capillary sequencer. RESULTS: Whereas no mutations were detected in intronic regions and in 2.7 kb of the promoter, two sequence variations were found within the coding sequence of apM-1. For both mutations, a polymerase chain reaction-(PCR) based restriction fragment length polymorphism (RFLP) analysis was developed, which provided a rapid screening method. A conservative T --> G transition at nucleotide + 45 within exon-2 [Gly15Gly] was detected with an allelic frequency of 0.9 for the wild-type allele and 0.1 for the mutated allele. In addition, a missense point mutation at nucleotide + 331 within exon-3 [Tyr111His] was detected with an allelic frequency of 0.97 for the wild-type allele and 0.03 for the mutated allele. This mutation replaces a tyrosine by an histidine within the carboxyterminal globular domain of apM-1. Concerning the Gly15Gly polymorphism, the TT genotype was found in 275 subjects (79.9%), the TG genotype in 67 subjects (19.5%) and the GG genotype in 2 subjects (0.6%): one with maturity onset diabetes of young age (MODY-diabetes) and one with Lipoatrophic Diabetes Syndrome (LPDS). Concerning the Tyr111His polymorphism, the TT genotype was found in 328 subjects (95.4%), the TC genotype in 15 subjects (4.3%) and the CC genotype in 1 subject (0.3%). CONCLUSION: The existence of two yet unknown mutations within the apM-1 gene was demonstrated and RFLP analysis was established for rapid screening. Well defined cohorts of patients are necessary to determine the putative role of apM-1 gene mutations in the pathogenesis of metabolic disorders.

Adipocytes↗

Colonization and bionomics of the sandfly Phlebotomus kazeruni from Sinai, Egypt.

Phlebotomuius kazeruni (Diptera: Psychodidae) females were collected by light-trap in southern Sinai, Egypt, and this sandfly species was colonized for the first time as a laboratory strain, maintained by the procedures of Modi & Tesh (1983). Laboratory-reared females did not lay eggs autogenously; they blood-fed more readily (P=0.02) on a hamster (37%) than a human (22%) during 1 h exposure. Fecundity of hamster-fed females was significantly greater than for those fed on human blood: 69.4 +/- 5.8 vs. 45.2 +/- 8.1 eggs/female from the first gonotrophic cycle. Pre-oviposition and egg incubation periods were significantly less for females fed on hamster compared with human blood, but the larval development and pupation periods were not affected by this difference in bloodmeal source. Egg to adult survival was equivalent (38%) for progeny of females blood-fed on hamster or human. The mean generation time of progeny from females fed on hamster (51.9 +/- 1.0 days) or human (53.3 +/- 1.7 days) was not significantly different. The sex ratio of adult male:female progeny was similar (P=0.2) for both hosts: 42:58% from hamster, 46:54% from human blood-fed female parents. Evidently P. kazeruni from Sinai is sufficiently anthropophagic to be a potential vector of Leishmania from rodents to humans.

Animals↗

Structural heterogeneity of carbohydrate modifications affects serospecificity of Campylobacter flagellins.

Flagellin from Campylobacter coli VC167 is post-translationally modified at > or = 16 amino acid residues with pseudaminic acid and three related derivatives. The predominant modification was 5,7-diacetamido-3,5,7,9 - tetradeoxy - l - glycero - l - manno - nonulosonic acid (pseudaminic acid, Pse5Ac7Ac), a modification that has been described previously on flagellin from Campylobacter jejuni 81-176. VC167 lacked two modi-fications present in 81-176 and instead had two unique modifications of masses 431 and 432 Da. Flagellins from both C. jejuni 81-176 and C. coli VC167 were also modified with an acetamidino form of pseudaminic acid (PseAm), but tandem mass spectrometry indicated that the structure of PseAm differed in the two strains. Synthesis of PseAm in C. coli VC167 requires a minimum of six ptm genes. In contrast, PseAm is synthesized in C. jejuni 81-176 via an alternative pathway using the product of the pseA gene. Mutation of the ptm genes in C. coli VC167 can be detected by changes in apparent Mr of flagellin in SDS-PAGE gels, changes in isoelectric focusing (IEF) patterns and loss of immunoreactivity with antiserum LAH2. These changes corresponded to loss of both 315 Da and 431 Da modifications from flagellin. Complementation of the VC167 ptm mutants with the 81-176 pseA gene in trans resulted in flagellins containing both 315 and 431 Da modifications, but these flagellins remained unreactive in LAH2 antibody, suggesting that the unique form of PseAm encoded by the ptm genes contributes to the serospecificity of the flagellar filament.

Amino Acid Sequence↗

Molecular genetics of diabetes mellitus in Chinese subjects: identification of mutations in glucokinase and hepatocyte nuclear factor-1alpha genes in patients with early-onset type 2 diabetes mellitus/MODY.

AIMS: To examine the prevalence of identified MODY-related genes in Chinese subjects with early onset Type 2 diabetes mellitus and a positive family history of diabetes and to look for possible associations between the gene mutations and the development of diabetes. METHODS: Ninety-two unrelated Chinese subjects with diabetes diagnosed before the age of 40 years who had a positive family history of diabetes were screened for mutations in hepatocyte nuclear factors (HNF-1alpha and HNF-4alpha) and glucokinase genes by direct sequencing. The family members of patients with mutations and 100 healthy controls were also examined. RESULTS: Mutations in the HNF-1alpha and the glucokinase genes were found in 5% and 3% of the diabetic subjects, respectively but no mutations were found in the coding region of the HNF-4alpha gene. Three mutations found in the glucokinase gene were novel missense mutations (I110T, A119D and G385V). The mutations in the HNF-1alpha gene were also new and included four missense mutations (G20R, R203H, S432C, I618M) and one splice acceptor site mutation (IVS2nt-1G-->A). Patients with mutations in these genes were clinically heterogeneous with respect to phenotype and basal pancreatic beta cell function. CONCLUSIONS: Genetic factors such as mutations in the HNF-1alpha and glucokinase genes may be important in the development of diabetes in Chinese people, especially when the disease is of early onset.

Adolescent↗

Type 2 diabetes mellitus in UK children--an emerging problem.

AIMS: Type 2 diabetes mellitus has never previously been described in UK children, although an increasing incidence in childhood is recognized in international studies. The prevalence of obesity in UK children is increasing and is a recognized risk factor for the development of diabetes. The aim of this study was to identify and characterize children with Type 2 diabetes in the West Midlands and Leicester. METHODS: Children were identified by contacting paediatricians responsible for diabetes in five hospitals. Details were collected on demographics, mode of presentation, investigations and treatment on a standard proforma. RESULTS: Eight girls were identified with Type 2 diabetes, aged 9-16 years and who were of Pakistani, Indian or Arabic origin. They were all overweight (percentage weight for height 141-209%) and had a family history of diabetes in at least two generations. They presented insidiously with hyperglycaemia and glycosuria without ketosis and five were asymptomatic. Islet cell antibodies measured in seven patients were negative. Four had acanthosis nigricans which is a cutaneous marker of insulin resistance and the other four had high plasma levels of insulin and/or C peptide. These patients are distinct from those with maturity-onset diabetes of the young (MODY). All were initially managed with dietary measures, seven have been treated with oral anti-diabetic agents of whom two have subsequently required insulin. CONCLUSIONS: These are the first UK case reports of Type 2 diabetes in children. Paediatricians need to be aware of the risk of Type 2 diabetes developing in childhood in high-risk ethnic groups, particularly in association with obesity and a positive family history.

Acanthosis Nigricans↗

Abnormal nephron development associated with a frameshift mutation in the transcription factor hepatocyte nuclear factor-1 beta.

BACKGROUND: The transcription factor hepatocyte nuclear factor (HNF)-1 beta functions as a homodimer or as a heterodimer with the structurally related protein HNF-1 alpha. Both are expressed sequentially in rat kidney development, with HNF-1 beta being detected from the earliest inductory phases. HNF-1 beta gene mutations are associated with a unique disorder characterized by maturity-onset diabetes of the young (MODY) and early-onset and progressive nondiabetic renal dysfunction, which may lead to chronic renal failure. METHODS: The HNF-1 beta gene was screened for mutations in six subjects with early-onset diabetes and a history of renal dysfunction in the subjects or their families. RESULTS: A novel frameshift mutation in exon 4 of the HNF-1 beta gene and a deletion of CCTCT at codons 328 to 329 were detected in one subject. She was diagnosed as diabetic at the age of 21 in her second pregnancy. Glucose tolerance rapidly deteriorated over 18 months as a result of beta-cell dysfunction. The HNF-1 beta mutation arose de novo on a paternal chromosome and cosegregated with renal abnormalities in her family. The proband had bilateral small cysts in normal-sized kidneys and a reduced creatinine clearance of 66 mL/min (NR 80-120). Her first pregnancy was terminated at 17 weeks following an ultrasound diagnosis of bilateral, nonfunctioning cystic kidneys. Her first-born child had a small multicystic, dysplastic right kidney and a dysplastic left kidney with a reduced creatinine clearance (40 mL/min per 1.73 m2). Histologic examination of the large (5.8 vs. 1.4 g), polycystic fetal kidneys showed no normal nephrogenesis. CONCLUSIONS: These studies indicate that HNF-1 beta plays a central role in normal kidney development and pancreatic beta-cell function, and suggest that one mechanism by which HNF-1 beta gene mutations may cause renal dysfunction are by their effects on nephron development.

Abortion, Induced↗

Alteration of insulin-binding receptors in non-insulin dependent diabetes of the young.

The behaviour of insulin binding receptors is rather unelucidated in non-insulin-dependent diabetes mellitus of the young. Authors in continuing their previous work studied the behaviour of insulin binding receptors of erythrocytes and monocytes in 9 MODY patients. They observed that specific insulin binding of circulating blood cells was significantly decreased in all cases as compared to the controls despite of a good state of metabolism (in the case of erythrocytes 4.63 +/- 1.1% vs. 6.03 +/- 1.7%, p less than 0.05, in the case of monocytes 2.3 +/- 1.2% vs. 3.6 +/- 1.4%, p less than 0.05). The lower value of insulin binding resulted from the decrease of receptor concentrations (in the case of erythrocytes 2.36 +/- 0.78 pmol/l vs. 3.81 +/- 1.14 pmol/l, p less than 0.05).

Adult↗

Mutations and intronic variants in the HNF-1 beta gene in a group of German and Czech Caucasians with type 2 diabetes mellitus and progressive diabetic nephropathy.

Mutations in the hepatocyte nuclear factor - 1 beta (HNF-1 beta) gene cause maturity onset diabetes of the young type 5 (MODY 5). A clinical feature of the resulting phenotype besides impaired glucose tolerance is a variety of renal abnormalities, ranging from renal cysts to end-stage renal failure. Using a candidate gene approach we investigated the prevalence of mutations in the HNF-1 beta gene in a group of 63 patients from two different European populations (33 Germans, 30 Czechs) with type 2 diabetes mellitus and diabetic nephropathy diagnosed by increased albuminuria (39 patients) or end-stage renal failure (24 patients). No mutations were found in any of the 9 exons or in a minimal promoter region. Three intronic variants (single nucleotide polymorphisms - SNPs) were detected. The frequencies of these variants showed no difference between the two studied populations and were comparable to data reported from healthy subjects. No association between SNPs or formed haplotypes and any clinical parameters (like age of disease onset, BMI and severity of renal failure) was found. The results confirm that the genetic variations in the HNF-1 beta gene would be a very uncommon cause of progressive nephropathy in patients with type 2 diabetes mellitus.

Age of Onset↗