PubMed Health⌕ Search

Biomedical subjects

Andrew T Hattersley

Publications and source records attributed to Andrew T Hattersley.

At least 19 recordsLinked to original sources
PubMed2007

Prevalence of permanent neonatal diabetes in Slovakia and successful replacement of insulin with sulfonylurea therapy in KCNJ11 and ABCC8 mutation carriers.

CONTEXT: Mutations in the KCNJ11 and ABCC8 genes encoding the pancreatic beta-cell K(ATP) channel have recently been shown to be the most common cause of permanent neonatal diabetes mellitus (PNDM). Information regarding the frequency of PNDM has been based mainly on nonpopulation or short-term collections only. Thus, the aim of this study was to identify the incidence of PNDM in Slovakia and to switch patients to sulfonylurea (SU) where applicable. DESIGN: We searched for PNDM patients in the Slovak Children Diabetes Registry. In insulin-treated patients who matched the clinical criteria for PNDM, the KCNJ11 or ABCC8 genes were sequenced, and mutation carriers were invited for replacement of insulin with SU. RESULTS: Eight patients with diabetes onset before the sixth month of life without remission were identified since 1981, which corresponds to the PNDM incidence in Slovakia of one case in 215,417 live births. In four patients, three different KCNJ11 mutations were found (R201H, H46Y, and L164P). Three patients with the KCNJ11 mutations (R201H and H46Y) were switched from insulin to SU, decreasing their glycosylated hemoglobin from 9.3-11.0% on insulin to 5.7-6.6% on SU treatment. One patient has a novel V86A mutation in the ABCC8 gene and was also substituted with SU. CONCLUSIONS: PNDM frequency in Slovakia is much higher (one in 215,417 live births) than previously suggested from international estimates (about one in 800,000). We identified one ABCC8 and four KCNJ11 mutation carriers, of whom four were successfully transferred to SU, dramatically improving their diabetes control and quality of life.

ATP-Binding Cassette Transporters↗
PubMed2006

A study of association between common variation in the growth hormone-chorionic somatomammotropin hormone gene cluster and adult fasting insulin in a UK Caucasian population.

BACKGROUND: Reduced growth during infancy is associated with adult insulin resistance. In a UK Caucasian cohort, the CSH1.01 microsatellite polymorphism in the growth hormone-chorionic somatomammotropin hormone gene cluster was recently associated with increases in adult fasting insulin of approximately 23 pmol/l for TT homozygote males compared to D1D1 or D2D2 homozygotes (P = 0.001 and 0.009; n = 206 and 92, respectively), but not for females. TT males additionally had a 547-g lower weight at 1 year (n = 270; P = 0.008) than D2D2 males. We sought to replicate these data in healthy UK Caucasian subjects. We genotyped 1396 subjects (fathers, mothers and children) from a consecutive birth study for the CSH1.01 marker and analysed genotypes for association with 1-year weight in boys and fasting insulin in fathers. RESULTS: We found no evidence for association of CSH1.01 genotype with adult male fasting insulin concentrations (TT/D1D1 P = 0.38; TT/D2D2 P = 0.18) or weight at 1 year in boys (TT/D1D1 P = 0.76; TT/D2D2 P = 0.85). For fasting insulin, our data can exclude the previously observed effect sizes as the 95 % confidence intervals for the differences observed in our study exclude increases in fasting insulin of 9.0 and 12.6 pmol/l for TT relative to D1D1 and D2D2 homozygotes, respectively. Whilst we have fewer data on boys' 1-year weight than the original study, our data can exclude a reduction in 1-year weight greater than 557 g for TT relative to D2D2 homozygotes. CONCLUSION: We have not found association of the CSH1.01 genotype with fasting insulin or weight at 1 year. We conclude that the original study is likely to have over-estimated the effect size for fasting insulin, or that the difference in results reflects the younger age of subjects in this study relative to those in the previous study.

Adult↗
PubMed2006

Triglyceride associated polymorphisms of the APOA5 gene have very different allele frequencies in Pune, India compared to Europeans.

BACKGROUND: The APOA5 gene variants, -1131T>C and S19W, are associated with altered triglyceride concentrations in studies of subjects of Caucasian and East Asian descent. There are few studies of these variants in South Asians. We investigated whether the two APOA5 variants also show similar association with various lipid parameters in Indian population as in the UK white subjects. METHODS: We genotyped 557 Indian adults from Pune, India, and 237 UK white adults for -1131T>C and S19W variants in the APOA5 gene, compared their allelic and genotype frequency and determined their association with fasting serum triglycerides, total cholesterol, HDL and LDL cholesterol levels using univariate general linear analysis. APOC3 SstI polymorphism was also analyzed in 175 Pune Indian subjects for analysis of linkage disequilibrium with the APOA5 variants. RESULTS: The APOA5 -1131C allele was more prevalent in Indians from Pune (Pune Indians) compared to UK white subjects (allele frequency 20% vs. 4%, p = 0.00001), whereas the 19W allele was less prevalent (3% vs. 6% p = 0.0015). Patterns of linkage disequilibrium between the two variants were similar between the two populations and confirmed that they occur on two different haplotypes. In Pune Indians, the presence of -1131C allele and the 19W allele was associated with a 19% and 15% increase respectively in triglyceride concentrations although only -1131C was significant (p = 0.0003). This effect size was similar to that seen in the UK white subjects. Analysis of the APOC3 SstI polymorphism in 175 Pune Indian subjects showed that this variant is not in appreciable linkage disequilibrium with the APOA5 -1131T>C variant (r2 = 0.07). CONCLUSION: This is the first study to look at the role of APOA5 in Asian Indian subjects that reside in India. The -1131C allele is more prevalent and the 19W allele is less prevalent in Pune Indians compared to UK Caucasians. We confirm that the APOA5 variants are associated with triglyceride levels independent of ethnicity and that this association is similar in magnitude in Asian Indians and Caucasians. The -1131C allele is present in 36% of the Pune Indian population making it a powerful marker for looking at the role of elevated triglycerides in important conditions such as pancreatitis, diabetes and coronary heart disease.

Adult↗
PubMed2006

A common haplotype of the glucokinase gene alters fasting glucose and birth weight: association in six studies and population-genetics analyses.

Fasting glucose is associated with future risk of type 2 diabetes and ischemic heart disease and is tightly regulated despite considerable variation in quantity, type, and timing of food intake. In pregnancy, maternal fasting glucose concentration is an important determinant of offspring birth weight. The key determinant of fasting glucose is the enzyme glucokinase (GCK). Rare mutations of GCK cause fasting hyperglycemia and alter birth weight. The extent to which common variation of GCK explains normal variation of fasting glucose and birth weight is not known. We aimed to comprehensively define the role of variation of GCK in determination of fasting glucose and birth weight, using a tagging SNP (tSNP) approach and studying 19,806 subjects from six population-based studies. Using 22 tSNPs, we showed that the variant rs1799884 is associated with fasting glucose at all ages in the normal population and exceeded genomewide levels of significance (P=10-9). rs3757840 was also highly significantly associated with fasting glucose (P=8x10-7), but haplotype analysis revealed that this is explained by linkage disequilibrium (r2=0.2) with rs1799884. A maternal A allele at rs1799884 was associated with a 32-g (95% confidence interval 11-53 g) increase in offspring birth weight (P=.002). Genetic variation influencing birth weight may have conferred a selective advantage in human populations. We performed extensive population-genetics analyses to look for evidence of recent positive natural selection on patterns of GCK variation. However, we found no strong signature of positive selection. In conclusion, a comprehensive analysis of common variation of the glucokinase gene shows that this is the first gene to be reproducibly associated with fasting glucose and fetal growth.

Adult↗
PubMed2006

Assessing newborn body composition using principal components analysis: differences in the determinants of fat and skeletal size.

BACKGROUND: Birth weight is a composite of skeletal size and soft tissue. These components are likely to have different growth patterns. The aim of this paper is to investigate the association between established determinants of birth weight and these separate components. METHODS: Weight, length, crown-rump, knee-heel, head circumference, arm circumference, and skinfold thicknesses were measured at birth in 699 healthy, term, UK babies recruited as part of the Exeter Family Study of Childhood Health. Corresponding measurements were taken on both parents. Principal components analysis with varimax rotation was used to reduce these measurements to two independent components each for mother, father and baby: one highly correlated with measures of fat, the other with skeletal size. RESULTS: Gestational age was significantly related to skeletal size, in both boys and girls (r = 0.41 and 0.52), but not fat. Skeletal size at birth was also associated with parental skeletal size (maternal: r = 0.24 (boys), r = 0.39 (girls) ; paternal: r = 0.16 (boys), r = 0.25 (girls)), and maternal smoking (0.4 SD reduction in boys, 0.6 SD reduction in girls). Fat was associated with parity (first borns smaller by 0.45 SD in boys; 0.31 SD in girls), maternal glucose (r = 0.18 (boys); r = 0.27 (girls)) and maternal fat (r = 0.16 (boys); r = 0.36 (girls)). CONCLUSION: Principal components analysis with varimax rotation provides a useful method for reducing birth weight to two more meaningful components: skeletal size and fat. These components have different associations with known determinants of birth weight, suggesting fat and skeletal size may have different regulatory mechanisms, which would be important to consider when studying the associations of birth weight with later adult disease.

Adiposity↗
PubMed2006

Switching from insulin to oral sulfonylureas in patients with diabetes due to Kir6.2 mutations.

BACKGROUND: Heterozygous activating mutations in KCNJ11, encoding the Kir6.2 subunit of the ATP-sensitive potassium (K(ATP)) channel, cause 30 to 58 percent of cases of diabetes diagnosed in patients under six months of age. Patients present with ketoacidosis or severe hyperglycemia and are treated with insulin. Diabetes results from impaired insulin secretion caused by a failure of the beta-cell K(ATP) channel to close in response to increased intracellular ATP. Sulfonylureas close the K(ATP) channel by an ATP-independent route. METHODS: We assessed glycemic control in 49 consecutive patients with Kir6.2 mutations who received appropriate doses of sulfonylureas and, in smaller subgroups, investigated the insulin secretory responses to intravenous and oral glucose, a mixed meal, and glucagon. The response of mutant K(ATP) channels to the sulfonylurea tolbutamide was assayed in xenopus oocytes. RESULTS: A total of 44 patients (90 percent) successfully discontinued insulin after receiving sulfonylureas. The extent of the tolbutamide blockade of K(ATP) channels in vitro reflected the response seen in patients. Glycated hemoglobin levels improved in all patients who switched to sulfonylurea therapy (from 8.1 percent before treatment to 6.4 percent after 12 weeks of treatment, P<0.001). Improved glycemic control was sustained at one year. Sulfonylurea treatment increased insulin secretion, which was more highly stimulated by oral glucose or a mixed meal than by intravenous glucose. Exogenous glucagon increased insulin secretion only in the presence of sulfonylureas. CONCLUSIONS: Sulfonylurea therapy is safe in the short term for patients with diabetes caused by KCNJ11 mutations and is probably more effective than insulin therapy. This pharmacogenetic response to sulfonylureas may result from the closing of mutant K(ATP) channels, thereby increasing insulin secretion in response to incretins and glucose metabolism. (ClinicalTrials.gov number, NCT00334711 [ClinicalTrials.gov].).

ATP-Binding Cassette Transporters↗
PubMed2006

Association of the calpain-10 gene with type 2 diabetes in Europeans: results of pooled and meta-analyses.

We conducted pooled and meta-analyses of the association of the calpain-10 gene (CAPN10) polymorphisms SNP-43, Indel-19 and SNP-63 individually and as haplotypes with type 2 diabetes (T2D) in 3237 patients and 2935 controls of European ancestry. In the pooled analyses, the common SNP-43*G allele was associated with modest but statistically significant increased risk of T2D (odds ratio (OR)=1.11 (95% confidence interval (CI), 1.02-1.20), P=0.01). Two haplotype combinations were associated with increased risk of T2D (1-2-1/1-2-1, OR=1.20 (1.03-1.41), P=0.02; and 1-1-2/1-2-1, OR=1.26 (1.01-1.59), P=0.04) and one with decreased risk (1-1-1/2-2-1, OR=0.86 (0.75-0.99), P=0.03). The meta-analysis also showed a significant effect of the 1-2-1/1-2-1 haplogenotype on risk (OR=1.25 (1.05-1.50), P=0.01). However, there was evidence for heterogeneity with respect to this effect (P=0.06). The heterogeneity appeared to be due to data sets in which the cases were selected from samples used in linkage studies of T2D. Using only the population-based case-control samples removed the heterogeneity (P=0.89) and strengthened the evidence for association with T2D in both the pooled (SNP-43*G, OR=1.19 (1.07-1.32), P=0.001; 1-2-1/1-2-1 haplogenotype, OR=1.46 (1.19-1.78), P=0.0003; 1-1-2/1-2-1 haplogenotype, OR=1.52 (1.12-2.06), P=0.007; and 1-1-1/2-2-1 haplogenotype, OR=0.83 (0.70-0.99), P=0.03) and the meta-analysis (SNP-43*G, OR=1.18 (1.05-1.32), P=0.005; 1-2-1/1-2-1 haplogenotype, OR=1.68 (1.33-2.11), P=0.00001). The pooled and meta-analyses as well as the linkage disequilibrium and haplotype diversity studies suggest a role for genetic variation in CAPN10 affecting risk of T2D in Europeans.

Calpain↗
PubMed2006

Isomers of the TCF1 gene encoding hepatocyte nuclear factor-1 alpha show differential expression in the pancreas and define the relationship between mutation position and clinical phenotype in monogenic diabetes.

The generation of multiple transcripts by mRNA processing has the potential to moderate differences in gene expression both between tissues and at different stages of development. Where gene function is compromised by mutation, the presence of multiple isoforms may influence the resulting phenotype. Heterozygous mutations in the transcription factor hepatocyte nuclear factor-1 alpha (HNF1A or TCF1 gene) result in early-onset diabetes as a result of pancreatic beta-cell dysfunction. We investigated the expression of the three alternatively processed isoforms of the HNF1A gene and their impact on the phenotype associated with mutations. Real-time PCR demonstrated variation in tissue expression of HNF1A isomers: HNF1A(A), with the lowest transactivation activity compared with the truncated isoforms HNF1A(B) and HNF1A(C), is the major isomer in liver (54%) and kidney (67%) but not in adult pancreas (24%) and islets (26%). However, in fetal pancreas HNF1A(A) is the major transcript (84%), which supports developmental regulation of isomer expression. We examined whether the isomers affected by the mutation altered the diabetes phenotype in 564 subjects with 123 mutations in HNF1A. Mutations that affected only isomer HNF1A(A) (exons 8-10) were diagnosed later (25.5 years) than mutations affecting all three isomers (exons 1-6) (18.0 years) (P=0.006). This first genotype/phenotype relationship described for patients with HNF1A mutations is explained by isomer structure and not by either mutation type or functional domain. We conclude that all three isomers may be critical for beta-cell function and could play a role in both the developing and mature beta cell.

Adolescent↗
PubMed2006

The functional "KL-VS" variant of KLOTHO is not associated with type 2 diabetes in 5028 UK Caucasians.

BACKGROUND: Klotho has an important role in insulin signalling and the development of ageing-like phenotypes in mice. The common functional "KL-VS" variant in the KLOTHO (KL) gene is associated with longevity in humans but its role in type 2 diabetes is not known. We performed a large case-control and family-based study to test the hypothesis that KL-VS is associated with type 2 diabetes in a UK Caucasian population. METHODS: We genotyped 1793 cases, 1619 controls and 1616 subjects from 509 families for the single nucleotide polymorphism (SNP) F352V (rs9536314) that defines the KL-VS variant. Allele and genotype frequencies were compared between cases and controls. Family-based analysis was used to test for over- or under-transmission of V352 to affected offspring. RESULTS: Despite good power to detect odds ratios of 1.2, there were no significant associations between alleles or genotypes and type 2 diabetes (V352 allele: odds ratio = 0.96 (0.84-1.09)). Additional analysis of quantitative trait data in 1177 healthy control subjects showed no association of the variant with fasting insulin, glucose, triglycerides, HDL- or LDL-cholesterol (all P > 0.05). However, the HDL-cholesterol levels observed across the genotype groups showed a similar, but non-significant, pattern to previously reported data. CONCLUSION: This is the first large-scale study to examine the association between common functional variation in KL and type 2 diabetes risk. We have found no evidence that the functional KL-VS variant is a risk factor for type 2 diabetes in a large UK Caucasian case-control and family-based study.

Adult↗
PubMed2006

Functional variation in VEGF is not associated with type 2 diabetes in a United Kingdom Caucasian population.

CONTEXT: Vascular endothelial growth factor (VEGF) is important for pancreatic beta cell development and function. Common variation in the VEGF gene is associated with altered serum concentrations of VEGF and with several diseases, but its role in type 2 diabetes is not known. The single nucleotide polymorphisms C-2578A (rs699947), G-1154A (rs1570360) and G-634C (rs2010963) in the 5'-region of VEGF are associated with altered serum concentrations of the protein. OBJECTIVE: We performed a large case-control and family-based study to test the hypothesis that these variants are associated with type 2 diabetes in a UK Caucasian population. PARTICIPANTS: We genotyped 1,969 cases, 1,625 controls and 530 families for the three single nucleotide polymorphisms. MAIN OUTCOME MEASURES: Allele and genotype frequencies were compared between cases and controls. Family-based analysis was used to test for over- or under-transmission of alleles to affected offspring. RESULTS: Despite good power (80%) to detect odds ratios of approximately 1.2, there were no significant associations between single alleles or genotypes and type 2 diabetes. Odds ratios (and 95% confidence intervals) comparing case and control allele frequencies for single nucleotide polymorphisms C-2578A, G-1154A and G-634C were 0.97 (0.88-1.07), 0.99 (0.90-1.09) and 0.97 (0.88-1.08), respectively. CONCLUSION: This is the first large-scale study to examine the association between common functional variation in VEGF and type 2 diabetes risk. We have found no evidence that these three single nucleotide polymorphisms, shown previously to alter VEGF concentrations, are risk factors for type 2 diabetes in a large UK Caucasian case-control and family-based study.

Adenine↗
PubMed2006

KCNJ11 activating mutations are associated with developmental delay, epilepsy and neonatal diabetes syndrome and other neurological features.

Heterozygous activating mutations in the gene encoding for the ATP-sensitive potassium channel subunit Kir6.2 (KCNJ11) have recently been shown to be a common cause of permanent neonatal diabetes. Kir6.2 is expressed in muscle, neuron and brain as well as the pancreatic beta-cell, so patients with KCNJ11 mutations could have a neurological phenotype in addition to their diabetes. It is proposed that some patients with KCNJ11 mutations have neurological features that are part of a discrete neurological syndrome termed developmental Delay, Epilepsy and Neonatal Diabetes (DEND), but there are also neurological consequences of chronic or acute diabetes. We identified KCNJ11 mutations in four of 10 probands with permanent neonatal diabetes and one affected parent; this included the novel C166F mutation and the previously described V59M and R201H. Four of the five patients with mutations had neurological features: the patient with the C166F mutation had marked developmental delay, severe generalised epilepsy, hypotonia and muscle weakness; mild developmental delay was present in the patient with the V59M mutation; one patient with the R201H mutation had acute and chronic neurological consequences of cerebral oedema and another had diabetic neuropathy from chronic hyperglycaemia. In conclusion, the clinical features in these patients support the existence of a discrete neurological syndrome with KCNJ11 mutations. The severe DEND syndrome was seen with the novel C166F mutation and mild developmental delay with the V59M mutation. These features differ markedly from the neurological consequences of acute or chronic diabetes.

Adolescent↗
PubMed2006

Allelic drop-out may occur with a primer binding site polymorphism for the commonly used RFLP assay for the -1131T>C polymorphism of the Apolipoprotein AV gene.

Apolipoprotein AV (ApoAV) gene variant, -1131T>C, is associated with increased triglyceride concentrations in all ethnic groups studied. An MseI based RFLP analysis is the most commonly used method for genotyping this SNP. We genotyped a large cohort comprising 1185 Asian Indians and 173 UK Caucasians for -1131T>C using an ARMS-PCR based tetra-primer method. For quality control, we re-genotyped approximately 10% random samples from this cohort utilizing the MseI RFLP, which showed a 2.9% (3/102) genotyping error rate between the two methods. To investigate further, we sequenced the 900 bp region around the -1131T>C polymorphism in 25 Asian Indians and 15 UK Caucasians and found a number of polymorphisms including the -987C>T polymorphism. Further analysis of the -987C>T SNP showed a higher rare allele frequency of 0.23 in Asian Indians (n = 158) compared to 0.09 in the UK Caucasians (n = 157). This SNP is located 4 bp from the 3' end of the RFLP forward primer and is in weak linkage disequilibrium with -1131T>C variant (r2 = 0.084 and D' = 1). Repeated RFLP analysis of seven subjects heterozygous for -987C>T (seven times), showed discordant results with the sequence at -1131T>C SNP nearly one third (15/49) of the time. We conclude that presence of -987C>T polymorphism in the forward primer of the MseI RFLP assay may lead to allelic drop-out and generate unforeseen errors in genotyping the -1131T>C polymorphism. Our results also emphasise the need for careful quality control in all molecular genetic studies, particularly while transferring genotyping methods between various ethnic groups.

Alleles↗
PubMed2006

Activating mutations in the gene encoding Kir6.2 alter fetal and postnatal growth and also cause neonatal diabetes.

CONTEXT: Birth weight is a bioassay for fetal insulin secretion because altered insulin secretion in utero alters insulin-mediated growth. Activating mutations in Kir6.2 are the major cause of neonatal diabetes and reduce insulin secretion by altering the closure of the beta-cell ATP-sensitive potassium channel in the presence of ATP. OBJECTIVE: Our objective was to examine fetal and postnatal growth in patients with activating Kir6.2 mutations and identify whether this was modified by severity of mutation or maternal diabetes. PATIENTS AND METHODS: We used sd scores (SDS) for birth and postnatal growth in an international series of patients (n = 49) with Kir6.2 mutations and related this to their clinical phenotype. RESULTS: Birth weight was greatly reduced [-1.73 (-3.68 to 1.41), median (range) SDS], but there was postnatal catch-up because present weight was normal [-0.37 (-4.37 to 2.34) SDS]. Catch-up growth for height and weight was not seen until insulin treatment was started. Birth weight was not influenced by severity of postnatal phenotype but was increased by maternal diabetes -0.12 vs. -1.81 SDS (P = 0.037). Patients with the severe neurological developmental delay, epilepsy, and neonatal diabetes syndrome did not catch up (present weight -2.2 vs. -0.24 SDS (P = 0.003). CONCLUSIONS: Kir6.2 mutations greatly reduce fetal insulin secretion and hence fetal growth, but this is independent of mutation severity. Increased fetal growth in response to maternal diabetes suggests that either the Kir6.2 mutated fetal beta-cell is still glucose responsive or there is a non-insulin-mediated increase in fetal growth. Postnatal catch-up requires insulin treatment but is complete, except in those with epilepsy.

Birth Weight↗
PubMed2006

A heterozygous activating mutation in the sulphonylurea receptor SUR1 (ABCC8) causes neonatal diabetes.

Neonatal diabetes is a genetically heterogeneous disorder with nine different genetic aetiologies reported to date. Heterozygous activating mutations in the KCNJ11 gene encoding Kir6.2, the pore-forming subunit of the ATP-sensitive potassium (K(ATP)) channel, are the most common cause of permanent neonatal diabetes. The sulphonylurea receptor (SUR) SUR1 serves as the regulatory subunit of the K(ATP) channel in pancreatic beta cells. We therefore hypothesized that activating mutations in the ABCC8 gene, which encodes SUR1, might cause neonatal diabetes. We identified a novel heterozygous mutation, F132L, in the ABCC8 gene of a patient with severe developmental delay, epilepsy and neonatal diabetes (DEND syndrome). This mutation had arisen de novo and was not present in 150 control chromosomes. Residue F132 shows evolutionary conservation across species and is located in the first set of transmembrane helices (TMD0) of SUR1, which is proposed to interact with Kir6.2. Functional studies of recombinant K(ATP) channels demonstrated that F132L markedly reduces the sensitivity of the K(ATP) channel to inhibition by MgATP and this increases the whole-cell K(ATP) current. The functional consequence of this ABCC8 mutation mirrors that of KCNJ11 mutations causing neonatal diabetes and provides new insights into the interaction of Kir6.2 and SUR1. As SUR1 is expressed in neurones as well as in beta cells, this mutation can account for both neonatal diabetes and the neurological phenotype. Our results demonstrate that SUR1 mutations constitute a new genetic aetiology for neonatal diabetes and that they act by reducing the K(ATP) channel's ATP sensitivity.

ATP-Binding Cassette Transporters↗
PubMed2006

Minireview: pharmacogenetics and beyond: the interaction of therapeutic response, beta-cell physiology, and genetics in diabetes.

Defining the molecular genetics of diabetes gives new insight into the underlying etiology and so should help improve treatment. The genetic etiology is now known for most patients with beta-cell monogenic diabetes, allowing genetic classification. We review how this genetic knowledge alters treatment. Patients with a glucose-sensing beta-cell defect due to glucokinase mutations have regulated, mild, fasting hyperglycemia. Oral hypoglycemic agents or low-dose insulin rarely improve glycemic control. Patients with hepatic nuclear factor-1alpha (HNF1alpha) mutations have progressive beta-cell deterioration and require treatment. HNF1alpha patients are 4 times more sensitive to sulfonylureas than matched type 2 diabetic patients. This is partly due to greater insulin secretion, reflecting the fact that the defect in HNF1alpha deficiency precedes the K(ATP) channel where sulfonylureas act. HNF1beta is expressed in pancreatic stem cells before differentiation into endocrine or exocrine cells, so patients with HNF1beta mutations have reduced pancreatic development, resulting in early-onset diabetes and exocrine dysfunction. These patients usually rapidly require insulin and are not sensitive to sulfonylureas. Thirty-five to 50% of patients diagnosed with diabetes before 6 months have a mutation in Kir6.2. The mutated KATP channel in these patients does not close in response to increased ATP concentrations, but can be closed when sulfonylureas bind to the sulfonylurea receptor 1 subunit of the channel by an ATP-independent route. These patients are usually insulin dependent, but have excellent glycemic control on high-dose sulfonylureas tablets. In conclusion, the defining of molecular genetic etiology in monogenic diabetes has identified several specific beta-cell defects, and these are critical in determining the response to treatment.

Animals↗
PubMed2006

Phenotypic multiple endocrine neoplasia type 2B, without endocrinopathy or RET gene mutation: implications for management.

The multiple endocrine neoplasia (MEN) type 2B is an autosomal dominant condition characterized by aggressive medullary C-cell tumors, pheochromocytoma, and a discrete physical appearance (marfanoid habitus, prominent corneal nerve fibers, thick lips, and mucosal and intestinal neuromas). A specific point mutation in the RET proto-oncogene is present in 95% cases. Occasionally cases present with the characteristic physical appearance of MEN 2B but no identifiable germline mutation or endocrinopathy, and it has been suggested that these patients may represent a discrete subgroup termed pure mucosal neuroma syndrome (MNS). We present a patient with MNS, who had a thyroidectomy at age 14.5 years with normal thyroid histology. Direct sequencing of all 20 exons of the RET gene showed no mutation. This case supports the suggestion that pure MNS can exist in the absence of an identifiable RET gene mutation. We suggest that prophylactic thyroidectomy is unnecessary in these patients although they should still be screened for endocrinopathy on a regular basis.

Adolescent↗
PubMed2006

The Exeter Family Study of Childhood Health (EFSOCH): study protocol and methodology.

The Exeter Family Study of Childhood Health is a prospective study, set up to test the fetal insulin hypothesis, and to identify genetic polymorphisms that play a role in determining birthweight and early postnatal growth. We recruited 1017 families from a postcode-defined area in central Exeter. Specific inclusion criteria were established to obtain a homogeneous, non-diabetic, UK Caucasian cohort. Detailed anthropometric measurements were taken from both parents at 28 weeks' gestation, and from their children at birth, 12 weeks, 1 year and 2 years of age. Insulin and other biochemical analysis were measured in fasting parental samples and an umbilical cord blood sample taken at delivery. Parental and offspring DNA were extracted to allow molecular genetic analysis of candidate genes implicated in fetal growth. This comprehensive data set is available on a disease-free cohort, and detailed preparatory work has ensured high levels of quality control. The study would welcome collaboration within strict confidentiality rules.

Adolescent↗