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P Froguel

Publications and source records attributed to P Froguel.

At least 163 records · Page 9Linked to original sources
PubMed1994

Insertion/deletion polymorphism of the angiotensin-converting enzyme gene is strongly associated with coronary heart disease in non-insulin-dependent diabetes mellitus.

Non-insulin-dependent diabetes mellitus (NIDDM) is considered a model of premature atherosclerosis with a strong genetic component. We have investigated the role of angiotensin-converting enzyme (ACE; EC 3.4.15.1) gene in 316 unrelated NIDDM individuals, 132 who had myocardial infarction or significant coronary stenoses and 184 with no history of coronary heart disease (CHD). A deletion-polymorphism in the ACE gene was recently reported to be associated with myocardial infarction especially in people classified as low risk. Here we report that the D allele of the ACE gene is a strong and independent risk factor for CHD in NIDDM patients. The D allele is associated with early-onset CHD in NIDDM, independently of hypertension and lipid values. A progressively increasing relative risk in individuals heterozygous and homozygous for the D allele was observed (odds ratios of 1.41 and 2.35, respectively; P < 0.007), suggesting a codominant effect on the cardiovascular risk. The percentage of CHD attributable to the ACE deletion allele was 24% in this NIDDM population. Identification of NIDDM patients carrying this putative CHD-susceptibility genotype would help early detection and treatment of CHD.

Alleles↗
PubMed1994

Association of elevated lipoprotein(a) levels and coronary heart disease in NIDDM patients. Relationship with apolipoprotein(a) phenotypes.

Non-insulin-dependent diabetes mellitus (NIDDM) is a strong and independent risk factor for coronary heart disease. We assessed the potential relationship between plasma Lp(a) levels, apo(a) phenotypes and coronary heart disease in a population of NIDDM patients. Seventy-one patients with coronary heart disease, who previously have had transmural myocardial infarction, or significant stenosis on coronary angiography, or positive myocardial thallium scintigraphy, or in combination, were compared with 67 patients without coronary heart disease, who tested negatively upon either coronary angiography, myocardial thallium scintigraphy or a maximal exercise test. The prevalence of plasma Lp(a) levels elevated above the threshold for increased cardiovascular risk (> 0.30 g/l) was significantly higher (p = 0.005) in patients with coronary heart disease (33.8%) compared to the control group (13.4%). The relative risk (odds ratio) of coronary heart disease among patients with high Lp(a) concentrations was 3.1 (95% confidence interval, 1.31-7.34; p = 0.01). The overall frequency distribution of apo(a) phenotypes differed significantly between the two groups (p = 0.043). However, the frequency of apo(a) isoforms of low apparent molecular mass (< or = 700 kDa) was of borderline significance (p = 0.067) between patients with or without coronary heart disease (29.6% and 16.4%, respectively). In this Caucasian population of NIDDM patients, elevated Lp(a) levels were associated with coronary heart disease, an association which was partially accounted for by the higher frequency of apo(a) isoforms of small size. In multivariate analyses, elevated levels of Lp(a) were independently associated with coronary heart disease (odds ratio 3.48, p = 0.0233).

Apolipoproteins A↗
PubMed1994

Genetic associations with human longevity at the APOE and ACE loci.

In an effort to dissect the genetic components of longevity, we have undertaken case-control studies of populations of centenarians (n = 338) and adults aged 20-70 years at several polymorphic candidate gene loci. Here we report results on two genes, chosen for their impact on cardiovascular risk, encoding apolipoprotein E (ApoE), angiotensin-converting enzyme (ACE). We find that the epsilon 4 allele of APOE, which promotes premature atherosclerosis, is significantly less frequent in centenarians than in controls (p < 0.001), while the frequency of the epsilon 2 allele, associated previously with type III and IV hyperlipidemia, is significantly increased (p < 0.01). A variant of ACE which predisposes to coronary heart disease is surprisingly more frequent in centenarians, with a significant increase of the homozygous genotype (p < 0.01). These associations provide examples of genetic influences on differential survival and may point to pleiotropic age-dependent effects on longevity.

Adult↗
PubMed1994

Maturity-onset diabetes of the young.

Maturity-onset diabetes of the young (MODY) is an autosomal dominant-subtype of noninsulin-dependent diabetes mellitus, characterized by an early age of onset. MODY is considered a model for genetic studies of noninsulin-dependent diabetes mellitus because of the availability of large multigenerational families, which make linkage analyses possible. So far, two MODY susceptibility loci have been reported, one unknown gene on chromosome 20q, and glucokinase on chromosome 7q. Glucokinase mutations appear to be the most common cause of MODY in the European population, being found in 60% of the families investigated. This form of diabetes results from a primary defect in insulin secretion due to the reduced enzymatic activity of the mutant glucokinase. The search for a third MODY gene will provide a better understanding of diabetes in childhood.

Age of Onset↗
PubMed1994

Higher maternal than paternal inheritance of diabetes in GK rats.

Results from crosses between Goto-Kakizaki (GK) rats, which exhibit spontaneous non-insulin-dependent diabetes mellitus (NIDDM), and outbred nondiabetic Wistar rats have demonstrated an effect of maternal inheritance on diabetes in offspring of the first generation (F1). At 6 weeks of age, F1 offspring of sex-directed crosses exhibited plasma glucose values intermediate between GK and Wistar parents. Hyperglycemia in F1 rats born of female GK rats (F1GK) was more marked than in those born of female Wistar (F1W) rats. At 3 months of age, F1 rats showed a marked impairment of both glucose tolerance and insulin secretion, which was intermediate between GK and Wistar rats. Glucose intolerance was more pronounced in F1GK rats than in F1W. By contrast, insulin secretion in F1W rats was more deteriorated than in F1GK rats. No deletion in mitochondrial DNA was observed in the GK rats, which decreased the possibility of a mitochondrial inheritance effect as an explanation of our findings. These data support a polygenic model in diabetes inheritance of NIDDM and suggest that, in addition to genetic factors, a perturbed maternal metabolism can contribute to its inheritance.

Animals↗
PubMed1994

Compensation in pancreatic beta-cell function in subjects with glucokinase mutations.

The relationship between the in vivo insulin secretory responsiveness of the pancreatic beta-cell to glucose and the flux of glucose through the enzyme glucokinase was investigated in six subjects with heterozygous glucokinase mutations and in six matched control subjects. This was done by combining data published previously on the in vivo dose-response relationships between glucose and insulin secretion and on the in vitro enzymatic properties of wild-type and mutant forms of glucokinase. The flux of glucose through glucokinase (GK flux) in these subjects was estimated using a model based on the approximate Michaelis-Menten kinetics of wild-type and mutant forms of the enzyme. In two subjects with glucokinase mutations, which resulted in only a small reduction in enzymatic activity, the decrease in insulin secretion was directly proportional to the decrease in GK flux predicted using a Michaelis-Menten model for both mutant and wild-type glucokinase. However, in four subjects with glucokinase mutations, which resulted in severe reductions in enzymatic activity, insulin secretion was reduced compared with control subjects but less than predicted. This latter result implies the existence of a compensatory change in the beta-cells of such subjects, which results in a relative increase in insulin secretory response. We propose modifications to the simple model relating glucose concentration and GK flux, including glucose-induced overexpression of the normal allele and a role of glucokinase regulatory protein. The modifications take into account the possibility that the degree of compensation may be directly related to the severity of the mutation.

Adolescent↗
PubMed1994

Maternally inherited diabetes and deafness is a distinct subtype of diabetes and associates with a single point mutation in the mitochondrial tRNA(Leu(UUR)) gene.

We have recently reported an A to G transition at nucleotide position 3243 in the mitochondrial DNA (mtDNA) tRNA(Leu(UUR)) gene in a large family with non-insulin-dependent diabetes mellitus (NIDDM). Characteristic was its maternal transmission and an associated sensorineural hearing loss. In a screening of a Dutch and French NIDDM population for the presence of the tRNA(Leu(UUR)) mutation we identified two new pedigrees in which NIDDM is present in combination with deafness. The mode of inheritance agrees with a maternal one. This result shows that patients with a phenotype of NIDDM and deafness can be identified within groups of NIDDM patients based on the tRNA(Leu(UUR)) mutation. The same mutation has also been linked to the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). How the same mutation can give rise to different clinical phenotypes is not clear. We obtained the complete mtDNA sequence from our initial pedigree and identified a number of additional mutations that could confer the phenotype of the tRNA(Leu(UUR)) mutation to diabetes. We examined the presence of these additional, potentially pathogenic mutations in the mtDNA from the two new pedigrees and from a previously described British pedigree. The absence of these mutations in all three pedigrees shows that the tRNA(Leu(UUR)) mutation alone associates with the phenotype of NIDDM and deafness. We conclude that maternally inherited diabetes and deafness is a distinct subtype of diabetes that is associated with a single mitochondrial tRNA(Leu(UUR)) mutation. We propose the abbreviation MIDD for this particular subtype.

Base Sequence↗
PubMed1994

Isolation of the human LIM/homeodomain gene islet-1 and identification of a simple sequence repeat polymorphism [corrected].

The islet-1 (Isl-1) gene encodes a protein that binds to the enhancer region of the insulin gene. Isl-1 is a member of the LIM/homeodomain family of transcription factors. Because insulin deficiency, either relative or absolute, is a cardinal feature of non-insulin-dependent diabetes mellitus (NIDDM), this study addressed the question of whether mutations in genes that regulate insulin production could be involved. Rat Isl-1 was the first insulin enhancer binding protein to be isolated, and, in this study, the rat gene was used to isolate a partial human islet Isl-1 cDNA and subsequently to isolate genomic clones. A simple sequence repeat was found in the Isl-1 gene, and polymerase chain reaction amplification of this region of genomic DNA revealed 12 alleles in St. Louis African-Americans (het = 0.87), 14 alleles in black Nigerians (het = 0.89), 8 alleles in Japanese (het = 0.69), and 8 alleles in Caucasians (het = 0.81). Genetic linkage analysis uniquely placed Isl-1 on chromosome 5q (D5S395[12.8 cM]Isl-1 [11.6 cM]D5S407). The simple sequence repeat polymorphism at the Isl-1 locus was used to evaluate mutations in this gene as a possible contributor to the pathogenesis of NIDDM. Allelic frequencies did not differ between patients with NIDDM (n = 165) and nondiabetic control subjects (n = 163) in two black populations (St. Louis African-Americans and Nigerians). Linkage analyses in 15 nonglucokinase maturity-onset diabetes of the young pedigrees indicated that linkage could be rejected (LOD score < -3.0) over a distance of 15 cM.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

Arginine-induced insulin release in glucokinase-deficient subjects.

OBJECTIVE: In eight glucokinase (GCK)-deficient subjects, we have investigated insulin secretion rates (ISRs) in response to intravenous arginine. Impairment in the enzymatic activity of mutant GCK leads to a reduced glycolytic flux in beta-cells. This defect translates in vivo as a right shift in the glucose/SR dose-response curve. Insulin secretion in response to other secretagogues has not been reported. RESEARCH DESIGN AND METHODS: The arginine test was performed immediately after a 2-h hyperglycemic (10 mM) clamp. ISR was computed by deconvolution of peripheral C-peptide levels. Linear regression analyses were performed to assess correlations between the beta-cell secretory responses to the arginine test, an intravenous glucose tolerance test (IVGTT), and a hyperglycemic clamp (areas under the C-peptide curves), and between these parameters and the glucose tolerance status (area under the glucose curve during an oral glucose tolerance test). RESULTS: Two minutes after the injection of arginine, the increment in ISR was 30.17 +/- 10.01 pmol insulin.kg-1.min-1 in patients and 36.25 +/- 15.46 pmol insulin.kg-1.min-1 in control subjects (P = 0.38). Throughout the experiment, increments in ISR were comparable in both groups. The amount of insulin secreted in response to arginine (0-5 min) was similar in patients and control subjects: 81 +/- 28 vs. 119 +/- 55 pmol/kg (P = 0.16), respectively. The arginine test C-peptide response was not correlated with the IVGTT or hyperglycemic clamp responses. The arginine test and hyperglycemic clamp responses were not correlated to the glucose tolerance status. The best predictor of the glucose tolerance was the C-peptide response to the IVGTT (r2 = 0.78; P = 0.002). CONCLUSIONS: beta-cell secretory increment in response to arginine was found to be in the normal range in GCK-deficient subjects. The arginine test does not seem to reflect either the beta-cell secretory defect or the glucose tolerance status of these subjects. IVGTT seems to be the best predictor of the latter parameter in this population.

Adolescent↗
PubMed1994

Multiple DNA variant association analysis: application to the insulin gene region in type I diabetes.

Association and linkage studies have shown that at least one of the genetic factors involved in susceptibility to insulin-dependent diabetes mellitus (IDDM) is contained within a 4.1-kb region of the insulin gene. Sequence analysis has led to the identification of 10 DNA variants in this region that are associated with increased risk for IDDM. These variants are in strong linkage disequilibrium with each other, and previous studies have failed to distinguish between the variant(s) that cause increased susceptibility to IDDM and others that are associated with the disease because of linkage disequilibrium. To address this problem, we have undertaken a large population study of French diabetics and controls and have analyzed genotype patterns for several of the variant sites simultaneously. This has led to the identification of a subset consisting of four variants (-2733AC, -23HphI, -365VNTR, and +1140AC), at least one of which appears to be directly implicated in disease susceptibility. The multiple-DNA-variant association-analysis approach that is applied here to the problem of identifying potential susceptibility variants in IDDM is likely to be important in studies of many other multifactorial diseases.

Diabetes Mellitus, Type 1↗
PubMed1994

Nonradioactive screening of glucokinase mutations in maturity onset diabetes of the young.

DNA mutations were previously identified in the glucokinase gene in 56% of French families affected with maturity onset diabetes of the young (MODY), an early onset autosomal dominant form of non-insulin-dependent diabetes mellitus (NIDDM). Mutations were found on almost all exons using the common radioactive single-strand conformation polymorphism (SSCP) technique. In this paper, we describe a non-isotopic SSCP method using the Pharmacia Biotech PhastSystem for the routine screening of new mutations in diabetic patients or in offsprings of diabetic patients. The use of the PhastSystem allowed us to easily and reproducibly optimize the electrophoretic conditions for each exon. We demonstrate the efficiency of this technique by identifying 8 mutations, 7 of which have never previously been detected, in patients referred to us for diagnostic purposes. It appears to be a sensible, easy and reliable method to improve the routine diagnosis of MODY in diabetic subjects or relatives and should be applicable to other genetic diseases.

DNA Mutational Analysis↗
PubMed1993

Structure/function studies of human beta-cell glucokinase. Enzymatic properties of a sequence polymorphism, mutations associated with diabetes, and other site-directed mutants.

Glucokinase plays a key role in the regulation of glucose metabolism in insulin-secreting pancreatic beta-cells and in the liver. Recent studies have shown that mutations in this enzyme can lead to the development of a form of non-insulin-dependent diabetes mellitus that is characterized by an autosomal dominant mode of inheritance and onset during childhood. Here, we report the catalytic properties of five additional missense mutations associated with diabetes (Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, Trp257-->Arg and Lys414-->Glu), one polymorphism present in both normal and diabetic subjects (Asp4-->Asn), and three site-directed mutations (Glu177-->Lys, Glu256-->Ala, and Lys414-->Ala). The Trp257-->Arg mutation generated an enzyme that had an activity that was less than 0.5% of that for native human beta-cell glucokinase. By contrast, the Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, and Lys414-->Glu mutations had a Vmax that was 20-100% of normal but a Km for glucose that was 8-14-fold greater than the native enzyme. There was no effect of the Asp4-->Asn polymorphism or the Glu177-->Lys substitution on glucokinase activity. The Lys414-->Ala substitution had no effect on Vmax but increased the Km for glucose 2-fold and the Glu256-->Ala substitution caused a approximately 200-fold decrease in Vmax. These studies have led to the identification of additional residues involved in glucokinase catalysis and substrate binding.

Amino Acid Sequence↗