Characterisation of HNF1A variants in paediatric diabetes in Norway using functional and clinical investigations to unmask phenotype and monogenic diabetes.

AIMS/HYPOTHESIS: Correctly diagnosing MODY is important, as individuals with this diagnosis can discontinue insulin injections; however, many people are misdiagnosed. We aimed to develop a robust approach for determining the pathogenicity of variants of uncertain significance in hepatocyte nuclear factor-1 alpha (HNF1A)-MODY and to obtain an accurate estimate of the prevalence of HNF1A-MODY in paediatric cases of diabetes. METHODS: We extended our previous screening of the Norwegian Childhood Diabetes Registry by 830 additional samples and comprehensively genotyped HNF1A variants in autoantibody-negative participants using next-generation sequencing. Carriers of pathogenic variants were treated by local healthcare providers, and participants with novel likely pathogenic variants and variants of uncertain significance were enrolled in an investigator-initiated, non-randomised, open-label pilot study (ClinicalTrials.gov registration no. NCT04239586). To identify variants associated with HNF1A-MODY, we functionally characterised their pathogenicity and assessed the carriers' phenotype and treatment response to sulfonylurea. RESULTS: In total, 615 autoantibody-negative participants among 4712 cases of paediatric diabetes underwent genetic sequencing, revealing 19 with HNF1A variants. We identified nine carriers with novel variants classified as variants of uncertain significance or likely to be pathogenic, while the remaining ten participants carried five pathogenic variants previously reported. Of the nine carriers with novel variants, six responded favourably to sulfonylurea. Functional investigations revealed their variants to be dysfunctional and demonstrated a correlation with the resulting phenotype, providing evidence for reclassifying these variants as pathogenic. CONCLUSIONS/INTERPRETATION: Based on this robust classification, we estimate that the prevalence of HNF1A-MODY is 0.3% in paediatric diabetes. Clinical phenotyping is challenging and functional investigations provide a strong complementary line of evidence. We demonstrate here that combining clinical phenotyping with functional protein studies provides a powerful tool to obtain a precise diagnosis of HNF1A-MODY.

Congenital hyperinsulinism. / Medfødt hyperinsulinisme.

This clinical review will give doctors who work with children and neonates an introduction to the diagnosis and treatment of congenital hyperinsulinism, the most common cause of persistent neonatal hypoglycaemia. The condition is a rare monogenic disorder characterised by elevated insulin secretion and is a result of mutations in genes that regulate insulin secretion from pancreatic beta cells. The anabolic effect of insulin induces systemic glucose uptake and inhibits gluconeogenesis, glycogenolysis, ketogenesis and lipolysis. Low levels of glucose and ketone bodies in the blood are harmful to the central nervous system and can lead to brain damage or death. Early diagnosis and treatment of congenital hyperinsulinism are therefore crucial for a good prognosis.

Exocrine pancreas insufficiency in chronic pancreatitis - Risk factors and associations with complications. A multicentre study of 1869 patients.

BACKGROUND/OBJECTIVES: There is scarce information about risk factors for exocrine pancreas insufficiency (EPI) in chronic pancreatitis (CP), and how it associates with other complications. The aim of the present study was to examine risk factors for EPI and associations to procedures and other CP related complications in a large, Northern European cohort. PATIENTS AND METHODS: We retrieved cross-sectional data on demographics, status on EPI, aetiological risk factors for CP, CP related complications as well as surgical and endoscopic treatment from the Scandinavian Baltic Pancreatic Club Database. Associations were assessed by univariate and multivariate logistic regression analyses. Results are presented as odds ratios (OR) with 95% confidence intervals. RESULTS: We included 1869 patients with probable or definitive CP in the study. Exocrine pancreas insufficiency was present in 849 (45.4%) of patients. In multivariate analyses, EPI associated with smoking aetiology (OR 1.47 (1.20-1.79), p < 0.001), and nutritional/metabolic aetiology (OR 0.52 (0.31-0.87), p = 0.01) to CP. Pancreatic or common bile duct stenting procedure and pancreatic resection were both associated with EPI (ORs 1.44 (1.15-1.80), p = 0.002 and 1.54 (1.02-2.33), p = 0.04, respectively). The presence of diabetes mellitus (OR 2.45 (1.92-3.15), p < 0.001), bile duct stenosis (OR 1.48 (1.09-2.00), p = 0.02) and underweight (2.05 (OR 1.40-3.02), p < 0.001) were all associated with presence of EPI. CONCLUSIONS: Smoking, bile duct stenosis, previous stenting and resection procedures are all associated with EPI in patients with CP. Presence of EPI were also associated with malnutrition and diabetes mellitus. Hence, intensive nutritional surveillance is needed in these patients.

KRAS mutation analysis by droplet digital PCR of duodenal juice from patients with MODY8 and other pancreatic diseases.

BACKGROUND: Maturity-onset diabetes of the young type 8 (MODY8 or CEL-MODY) is an inherited pancreatic disease characterized by chronic inflammation of the pancreas and diabetes. It is not known whether MODY8 patients have increased risk for developing pancreatic cancer. We investigated KRAS mutation load in duodenal juice from MODY8 patients, comparing with other groups of pancreatic disease. METHODS: Droplet digital PCR (ddPCR) was used to detect KRAS codon 12/13/61 mutations in duodenal juice sampled from 11 MODY8 patients, nine healthy subjects and 100 patients clinically investigated due to suspected pancreatic disease. RESULTS: KRAS mutations were detected in 4/11 patients with MODY8 (36%), 1/9 healthy subjects (11%), 15/44 patients with chronic pancreatitis (CP, 34%), 3/5 patients with pancreatic ductal adenocarcinoma (PDAC, 60%), 3/20 patients with acute pancreatitis (15%), 0/13 patients with other pancreatic disorders and 2/18 patients with nonpancreatic gastrointestinal disease (11%). Of the 28 positive juice samples, 25 (89%) had low-abundance mutations in codons 12/13, with a variant allele frequency (VAF) less than 1%. KRAS-positive patients with MODY8 or CP had significantly lower VAFs than patients with PDAC (Mann-Whitney U test; p = 0.041). Although the overall mutation detection rate was higher for subjects ≥50 years old (26%) than for younger subjects (15%), the difference was not statistically significant. CONCLUSIONS: KRAS mutations were detectable in duodenal juice from MODY8 patients, but with low abundance and at the same frequency as in CP patients. The discriminative value of the analysis with regard to other pancreatic disease was limited.

Aetiological risk factors are associated with distinct imaging findings in patients with chronic pancreatitis: A study of 959 cases from the Scandinavian Baltic Pancreatic Club (SBPC) imaging database.

OBJECTIVES: The relation between aetiology and structural changes of the pancreas in patients with chronic pancreatitis (CP) is not fully understood. Earlier studies are limited by focusing on selected factors in studies of limited sample size. We aimed to use a large dataset to explore associations between aetiology and pancreatic morphology in CP. METHODS: Subjects with definite or probable CP according to the M-ANNHEIM diagnostic criteria were included in this multicentre cross-sectional observational study and assessed using a standardized and validated CP imaging system. We performed multivariate logistic regression to analyse if aetiological factors adjusted for covariates were independently associated with morphological pancreatic features. RESULTS: We included 959 patients (66% males). Mean (SD) age was 55 (14) years. Pancreatic structural changes were found in 94% of the subjects: 67% had calcifications, 59% main pancreatic duct dilatation, 33% pseudo-cysts and 22% pancreatic atrophy. Alcohol abuse was independently associated with pancreatic calcifications (odds ratio (OR, [95% CI]); 1.61, [1.09, 2.37]) and focal acute pancreatitis (OR; 2.13, [1.27, 3.56]), whereas smoking was independently associated with more severe calcifications (OR; 2.09, [1.34, 3.27]) and involvement of the whole gland (OR; 2.29, [1.61, 3.28]). Disease duration was positively associated with calcifications (OR; (per year) 1.05 [1.02, 1.08]) and pancreatic atrophy (OR; 1.05 [1.02, 1.08]) and negatively associated with focal acute pancreatitis (OR 0.91, [0.87, 0.95] and pseudo cysts (OR; 0.96, [0.93, 0.98]). CONCLUSION: In this large-scale study, etiological risk factors and disease duration in CP were independently associated with specific structural pancreatic imaging changes.

Patient reported exposure to smoking and alcohol abuse are associated with pain and other complications in patients with chronic pancreatitis.

BACKGROUND/OBJECTIVES: Smoking and alcohol abuse are established risk factors for chronic pancreatitis (CP). Few studies have examined how exposure to smoking and alcohol abuse act as risk factors for complications in CP. Our aim was to examine associations between patient reported exposure to smoking and alcohol abuse and complications in CP in a large cohort of patients from the Scandinavian and Baltic countries. METHODS: We retrieved data on demographics, CP related complications and patients' histories of exposure to smoking and alcohol abuse from the Scandinavian Baltic Pancreatic Club database. Associations were investigated by univariate and multivariate logistic regression analyses. Results are presented as odds ratios (OR) with 95% confidence intervals. RESULTS: A complete history of smoking and alcohol exposure was available for 932 patients. In multivariate regression analyses, the presence of pain and exocrine pancreatic insufficiency were both significantly associated with history of smoking (OR 1.94 (1.40-2.68), p < 0.001 and OR 1.89 (1.36-2.62), p < 0.001, respectively) and alcohol abuse (OR 1.66 (1.21-2.26), p = 0.001 and 1.55 (1.14-2.11), p = 0.005, respectively). Smoking was associated with calcifications (OR 2.89 (2.09-3.96), p < 0.001), moderate to severe ductal changes (OR 1.42 (1.05-1.92), p = 0.02), and underweight (OR 4.73 (2.23-10.02), p < 0.001). History of alcohol abuse was associated with pseudocysts (OR 1.38 (1.00-1.90) p = 0.05) and diabetes mellitus (OR 1.44 (1.03-2.01), p = 0.03). There were significantly increased odds-ratios for several complications with increasing exposure to smoking and alcohol abuse. CONCLUSION: Smoking and alcohol abuse are both independently associated with development of complications in patients with CP. There seems to be a dose-dependent relationship between smoking and alcohol abuse and complications in CP.

The role of the carboxyl ester lipase (CEL) gene in pancreatic disease.

The enzyme carboxyl ester lipase (CEL), also known as bile salt-dependent or -stimulated lipase (BSDL, BSSL), hydrolyzes dietary fat, cholesteryl esters and fat-soluble vitamins in the duodenum. CEL is mainly expressed in pancreatic acinar cells and lactating mammary glands. The human CEL gene resides on chromosome 9q34.3 and contains a variable number of tandem repeats (VNTR) region that encodes a mucin-like protein tail. Although the number of normal repeats does not appear to significantly influence the risk for pancreatic disease, single-base pair deletions in the first VNTR repeat cause a syndrome of endocrine and exocrine dysfunction denoted MODY8. Hallmarks are low fecal elastase levels and pancreatic lipomatosis manifesting before the age of twenty, followed by development of diabetes and pancreatic cysts later in life. The mutant protein forms intracellular and extracellular aggregates, suggesting that MODY8 is a protein misfolding disease. Recently, a recombined allele between CEL and its pseudogene CELP was discovered. This allele (CEL-HYB) encodes a chimeric protein with impaired secretion increasing five-fold the risk for chronic pancreatitis. The CEL gene has proven to be exceptionally polymorphic due to copy number variants of the CEL-CELP locus and alterations involving the VNTR. Genome-wide association studies or deep sequencing cannot easily pick up this wealth of genetic variation. CEL is therefore an attractive candidate gene for further exploration of links to pancreatic disease.

Secretin-stimulated ultrasound estimation of pancreatic secretion in cystic fibrosis validated by magnetic resonance imaging.

OBJECTIVES: Secretin-stimulated magnetic resonance imaging (s-MRI) is the best validated radiological modality assessing pancreatic secretion. The purpose of this study was to compare volume output measures from secretin-stimulated transabdominal ultrasonography (s-US) to s-MRI for the diagnosis of exocrine pancreatic failure in cystic fibrosis (CF). METHODS: We performed transabdominal ultrasonography and MRI before and at timed intervals during 15 minutes after secretin stimulation in 21 CF patients and 13 healthy controls. To clearly identify the subjects with reduced exocrine pancreatic function, we classified CF patients as pancreas-sufficient or -insufficient by secretin-stimulated endoscopic short test and faecal elastase. RESULTS: Pancreas-insufficient CF patients had reduced pancreatic secretions compared to pancreas-sufficient subjects based on both imaging modalities (p < 0.001). Volume output estimates assessed by s-US correlated to that of s-MRI (r = 0.56-0.62; p < 0.001). Both s-US (AUC: 0.88) and s-MRI (AUC: 0.99) demonstrated good diagnostic accuracy for exocrine pancreatic failure. CONCLUSIONS: Pancreatic volume-output estimated by s-US corresponds well to exocrine pancreatic function in CF patients and yields comparable results to that of s-MRI. s-US provides a simple and feasible tool in the assessment of pancreatic secretion. KEY POINTS: • Cystic fibrosis patients with affected pancreas have reduced pancreatic secretions. • Secretin-stimulated sonography is a simple and feasible method to assess pancreatic output. • Secretin-simulated MRI is a more precise method to assess pancreatic secretions. • The sonographic and MRI methods yielded comparable pancreatic secretory output estimates.

Analysis of lipase activity in duodenal juice. Comparison of an automated spectrophotometric assay to a fluorometric microplate assay, and factors affecting sample stability.

BACKGROUND: Direct pancreas function testing (DPFT) has been regarded as gold standard for assessment of exocrine pancreas function. One of the outcomes from DPFT is pancreatic lipase activity in duodenal juice, but no standard assay for measuring pancreas lipase activity in duodenal juice exists. AIMS: To optimize and evaluate an autoanalyzer assay for measuring lipase activity in duodenal juice. METHODS: We used samples of duodenal juice from our biobank, collected through a short endoscopic secretin test in patients with suspected exocrine pancreas insufficiency. Samples were analyzed on a Cobas autoanalyzer (Roche Diagnostics), using a colorimetric, kinetic enzyme activity assay. We compared stability of samples diluted in saline to samples diluted in 3-(N-morpholino) propane sulfonic acid (MOPS) buffer added bovine serum albumin (BSA). Results from the Cobas assay were compared to Confluolip method, a fluorometric, kinetic enzyme assay, modified to fit into a microplate setting. RESULTS: We tested the stability of 54 samples from 21 patients. Diluting samples with MOPS buffer added BSA gave stable results, and was superior to diluting samples in saline. We compared the two assays in 50 samples from 20 patients and found a good correlation between the two assays (r = 0.91, p < .001). There was a significant proportional bias between the two assays, but no significant systematic bias. CONCLUSION: Pancreatic lipase activity in duodenal juice samples diluted in MOPS buffer added BSA is stable for one hour at room temperature. Quantification of lipase activity in duodenal juice using a standard automated activity assay has comparable accuracy to a manual fluorometric method.

Fecal fat and energy loss in pancreas exocrine insufficiency: the role of pancreas enzyme replacement therapy.

BACKGROUND: Chronic pancreatitis (CP) can lead to severe pancreatic exocrine insufficiency (PEI). Pancreatic enzyme replacement therapy (PERT) is well established, but knowledge of the physiological response to increasing doses on fecal fat- and energy loss is scarce. METHODS: We included 10 patients with CP and established PEI and 12 healthy controls for a prospective interventional study. Subjects received no PERT in the first week followed by four weeks PERT incrementally increasing doses every week. For each week, three-day stool collection followed three days registration of nutritional intake. We measured the fecal output of fat and energy by van de Kamer titration and decomposition vessel calorimetry, respectively. We calculated fecal fat- and energy loss per day, the coefficient of fat absorption (CFA) and coefficient of energy absorption (CEA). RESULTS: Without PERT treatment, CP patients with PEI had significantly higher daily fecal fat and energy loss (p = .022; p = .035) compared to HC. In CP patients, there was a significant reduction of fecal fat and energy loss (p = .045; p = .037) when PERT doses reached maximum intake of 75,000 units per meal. In CP patients, there was a strong positive correlation between fecal loss of energy and fat (r = 0.99), and between fecal loss of energy and daily stool weight (r = 0.97). CFA and CEA correlated negatively with daily fecal fat loss (r = -0.72) and fecal energy loss (r = -0.65). CONCLUSIONS: PERT reduces fecal energy and fat loss in patients with CP and PEI. Fecal energy loss in CP patients is strongly dependent on fecal fat loss, and on fecal weight.

Analysis of amylase in duodenal juice - Automated kinetic spectrophotometric analysis versus manual colorimetric endpoint assay.

OBJECTIVE: The measurement of duodenal amylase by a colorimetric end-point assay has been the most used method for amylase activity analyses. The method is manual, time consuming and dependent on specialized equipment. In this study, we compare an automated kinetic spectrophotometric method for pancreatic amylase measurement in duodenal juice with a standardized colorimetric end-point assay. METHODS: We used specimen of duodenal juice at random from a biobank obtained by short endoscopic secretin test in patients with suspected exocrine pancreatic failure of different reasons. Duodenal juice was tested for amylase activity with a conservative manual colorimetric endpoint assay (Phadebas Amylase test, Magle AB) and an automated enzymatic kinetic spectrophotometric method using standard reagents for pancreatic amylase activity for Cobas c111 (Roche Diagnostics). RESULTS: 52 samples for assay of amylase were analyzed in pairs. Correlation between measurements with the two methods was r = 0.99 (p < 0.001), linear regression 0.99 (p < 0.001). CONCLUSION: Quantification of duodenal amylase activity with automated spectrophotometry has excellent correlation to measurements made by the manual method. This allows for standardized, center independent analyses of duodenal amylase for the assessment of acinar pancreatic function.

Automated spectrophotometric bicarbonate analysis in duodenal juice compared to the back titration method.

OBJECTIVES: We have recently evaluated a short endoscopic secretin test for exocrine pancreatic function. Bicarbonate concentration in duodenal juice is an important parameter in this test. Measurement of bicarbonate by back titration as the gold standard method is time consuming, expensive and technically difficult, thus a simplified method is warranted. We aimed to evaluate an automated spectrophotometric method in samples spanning the effective range of bicarbonate concentrations in duodenal juice. We also evaluated if freezing of samples before analyses would affect its results. METHODS: Patients routinely examined with short endoscopic secretin test suspected to have decreased pancreatic function of various reasons were included. Bicarbonate in duodenal juice was quantified by back titration and automatic spectrophotometry. Both fresh and thawed samples were analysed spectrophotometrically. RESULTS: 177 samples from 71 patients were analysed. Correlation coefficient of all measurements was r = 0.98 (p < 0.001). Correlation coefficient of fresh versus frozen samples conducted with automatic spectrophotometry (n = 25): r = 0.96 (p < 0.001) CONCLUSIONS: The measurement of bicarbonate in fresh and thawed samples by automatic spectrophotometrical analysis correlates excellent with the back titration gold standard. This is a major simplification of direct pancreas function testing, and allows a wider distribution of bicarbonate testing in duodenal juice. Extreme values for Bicarbonate concentration achieved by the autoanalyser method have to be interpreted with caution.

Carboxyl-ester lipase maturity-onset diabetes of the young disease protein biomarkers in secretin-stimulated duodenal juice.

Patients with carboxyl-ester lipase-maturity-onset diabetes of the young (CEL-MODY) display distinct disease stages toward the development of monogenic diabetes and exocrine pancreatic disease. The finding of differentially increased proteins, some related to MAPK signaling, in a discovery proteomics study of secretin-stimulated duodenal juice in three CEL-MODY patients, prompted us to monitor their abundance in an extensive number of CEL-MODY subjects at different disease stages and controls using targeted proteomics. In the current study, we demonstrate the feasibility of selected reaction monitoring assays to quantify protein levels in secretin-stimulated duodenal juice. Furthermore, we define a set of five peptides for potential use as diagnostic tests in CEL-MODY patients. Finally, we propose a further set of seven proteins with a likely pathogenic role in CEL-MODY disease progression.

Diagnostic accuracy of secretin-stimulated ultrasonography of the pancreas assessing exocrine pancreatic failure in cystic fibrosis and chronic pancreatitis.

OBJECTIVE: Volume output failure is a feature of decreasing exocrine pancreatic function. This parameter is assessed by secretin-stimulated MRI in several studies. Our purpose was to evaluate ultrasonography of the fluid in the descending duodenum and Wirsung duct (WD) after secretin stimulation as a measure of pancreatic fluid flow in patients expected to have severe output failure. MATERIAL AND METHODS: We included subjects with chronic pancreatitis (CP), cystic fibrosis (CF) and a group of healthy controls in a prospective observation study. Transabdominal ultrasonography was performed before and during 15 min after secretin i.v. duodenal juice was collected by endoscopic short test (EST), and bicarbonate concentration measured. Patient groups were classified according to exocrine pancreatic function. RESULTS: Pancreatic insufficient CF (CFI) patients and CP insufficient (CPI) patients showed less duodenal fluid filling compared to other groups (p < 0.001). Measures of the WD diameter could only identify the most severe failure in the CFI group (p < 0.001). CONCLUSION: Secretin-stimulated ultrasonography can be used to assess pancreatic fluid flow and may be combined with EST in the evaluation of exocrine pancreatic function. Fluid filling in the descending part of duodenum was the most accurate predictor of pancreatic insufficiency in both patient groups. The test demonstrated better diagnostic accuracy diagnosing exocrine pancreatic failure in the CF patients than in CP patients.

Derivation of human induced pluripotent stem cells from patients with maturity onset diabetes of the young.

Maturity onset diabetes of the young (MODY) is an autosomal dominant disease. Despite extensive research, the mechanism by which a mutant MODY gene results in monogenic diabetes is not yet clear due to the inaccessibility of patient samples. Induced pluripotency and directed differentiation toward the pancreatic lineage are now viable and attractive methods to uncover the molecular mechanisms underlying MODY. Here we report, for the first time, the derivation of human induced pluripotent stem cells (hiPSCs) from patients with five types of MODY: MODY1 (HNF4A), MODY2 (GCK), MODY3 (HNF1A), MODY5 (HNF1B), and MODY8 (CEL) with a polycistronic lentiviral vector expressing a Cre-excisable human "stem cell cassette" containing the four reprogramming factors OCT4, KLF4, SOX2, and CMYC. These MODY-hiPSCs morphologically resemble human pluripotent stem cells (hPSCs), express pluripotency markers OCT4, SOX2, NANOG, SSEA-4, and TRA-1-60, give rise to derivatives of the three germ layers in a teratoma assay, and are karyotypically normal. Overall, our MODY-hiPSCs serve as invaluable tools to dissect the role of MODY genes in the development of pancreas and islet cells and to evaluate their significance in regulating beta cell function. This knowledge will aid future attempts aimed at deriving functional mature beta cells from hPSCs.

Assessment of exocrine pancreatic function by secretin-stimulated magnetic resonance cholangiopancreaticography and diffusion-weighted imaging in healthy controls.

PURPOSE: To characterize and quantify exocrine pancreatic function by secretin-stimulated magnetic resonance cholangiopancreaticography (s-MRCP) and diffusion-weighted imaging (DWI) in healthy subjects and compare these findings to morphological features, ie, pancreatic volume and secretin-stimulated peak bicarbonate concentration measured in pancreatic juice. MATERIALS AND METHODS: Pancreatic magnetic resonance imaging (MRI) (1.5 T) was performed in 20 healthy volunteers among which 10 underwent gastroscopy with duodenal intubation. MRI included T2-weighted imaging and DWI acquired before and 1, 5, 9, and 13 minutes after secretin administration. Secreted pancreatic juice volumes were calculated based on the sequential T2-weighted images and pancreatic volumes and apparent diffusion coefficient (ADC) values were estimated. RESULTS: The mean pancreatic secretion rate declined from 9.5 mL/min at 1-5 minutes (postsecretin) to 2.9 mL/min at 9-13 minutes. Pancreatic head ADC values significantly increased from baseline (1.29 × 10(-3) mm(2) /s) to 1 minute postsecretin (1.48 × 10(-3) mm(2) /s) (P = 0.003). Secreted pancreatic juice volume at 1 minute after secretin correlated positively with peak bicarbonate concentration (n = 10, P = 0.05). CONCLUSION: Secretin-stimulated MRCP and DWI can characterize and quantify exocrine pancreatic function in healthy subjects. These imaging methods may prove relevant for patients with exocrine pancreatic dysfunction.

Rectal sensitivity correlated with gastrointestinal-mediated glucose disposal, but not the incretin effect.

OBJECTIVE: The mechanisms behind the diminished incretin effect in type 2 diabetes are uncertain, but impaired vagal transmission has been suggested. We aimed to investigate the association between the incretin effect and autonomic neuropathy, and the degree of dysglycaemia and duration of diabetes. DESIGN AND METHODS: For a cross-sectional study, we included participants with either longstanding type 2 diabetes, recent onset, untreated diabetes and controls without diabetes matched for age, sex and body mass index. Autonomic nerve function was assessed with cardiovascular reflex tests, heart rate variability and sudomotor function. Visceral afferent nerves in the gut were tested performing rapid rectal balloon distention. An oral glucose tolerance test and an intravenous isoglycaemic glucose infusion were performed to calculate the incretin effect and gastrointestinal-mediated glucose disposal (GIGD). RESULTS: Sixty-five participants were recruited. Participants with diabetes had rectal hyposensitivity for earliest sensation (3.7 ± 1.1 kPa in longstanding, 4.0 ± 1.3 in early), compared to controls (3.0 ± 0.9 kPa), p = .005. Rectal hyposensitivity for earliest sensation was not associated with the incretin effect (rho = -0.204, p = .106), but an association was found with GIGD (rho -0.341, p = .005). Incretin effect and GIGD were correlated with all glucose values, HbA1c and duration of diabetes. CONCLUSIONS: Rectal hyposensitivity was uncovered in both longstanding and early type 2 diabetes, and was not associated with the incretin effect, but with GIGD, implying a potential link between visceral neuropathy and gastrointestinal handling of glucose. Both the incretin effect and GIGD were associated with the degree of dysglycaemia and the duration of diabetes. PREVIOUSLY PUBLISHED: Some of the data have previously been published and presented as a poster on the American Diabetes Association 83rd Scientific Sessions: Meling et al; 1658-P: Rectal Hyposensitivity, a Potential Marker of Enteric Autonomic Nerve Dysfunction, Is Significantly Associated with Gastrointestinally Mediated Glucose Disposal in Persons with Type 2 Diabetes. Diabetes 20 June 2023; 72 (Supplement_1): 1658-P. https://doi.org/10.2337/db23-1658-P.

Molecular mechanism of HNF-1A-mediated HNF4A gene regulation and promoter-driven HNF4A-MODY diabetes.

Monogenic diabetes is a gateway to precision medicine through molecular mechanistic insight. Hepatocyte nuclear factor 1A (HNF-1A) and HNF-4A are transcription factors that engage in crossregulatory gene transcription networks to maintain glucose-stimulated insulin secretion in pancreatic ß cells. Variants in the HNF1A and HNF4A genes are associated with maturity-onset diabetes of the young (MODY). Here, we explored 4 variants in the P2-HNF4A promoter region: 3 in the HNF-1A binding site and 1 close to the site, which were identified in 63 individuals from 21 families of different MODY disease registries across Europe. Our goal was to study the disease causality for these variants and to investigate diabetes mechanisms on the molecular level. We solved a crystal structure of HNF-1A bound to the P2-HNF4A promoter and established a set of techniques to probe HNF-1A binding and transcriptional activity toward different promoter variants. We used isothermal titration calorimetry, biolayer interferometry, x-ray crystallography, and transactivation assays, which revealed changes in HNF-1A binding or transcriptional activities for all 4 P2-HNF4A variants. Our results suggest distinct disease mechanisms of the promoter variants, which can be correlated with clinical phenotype, such as age of diagnosis of diabetes, and be important tools for clinical utility in precision medicine.

An Egyptian family with H syndrome due to a novel mutation in SLC29A3 illustrating overlapping features with pigmented hypertrichotic dermatosis with insulin-dependent diabetes and Faisalabad histiocytosis.

The SLC29A3 gene, encoding hENT3, a member of the equilibrative nucleoside transporter family, has recently been found mutated in Faisalabad histiocytosis, pigmented hypertrichotic dermatosis with insulin-dependent diabetes, familial sinus histiocytosis with massive lymphadenopathy (SHML), and H syndromes. We here report clinical and genetic findings of an Egyptian family with H syndrome. We describe two siblings, a 19-yr old girl and a 15-yr old boy, of consanguineous parents. From 5 yr of age, the girl developed bilateral flexion deformity of interphalengeal joints and insulin-dependent diabetes mellitus. At age 7 yr, prominent hyperpigmented patches appeared on the skin at lower limbs, genitalia, and trunk. On clinical examination, she had hepatosplenomegaly, generalized lymphadenopathy, left ventricular hypertrophy, sensorineural hearing loss, hypogonadism, short stature, and characteristic dysmorphic features. Her brother had fixed flexion contractures of the feet, profound sensorineural hearing loss, characteristic dysmorphic features, but no diabetes. DNA sequence analysis revealed a homozygous mutation (c.300+1G>C) in SLC29A3 in both siblings. The phenotype and genotype of the siblings were compatible with that of the H syndrome, although the features were overlapping with those found in pigmented hypertrichotic dermatosis with insulin-dependent diabetes, familial SHML, and Faisalabad histiocytosis, indicating that these four syndromes may be regarded as one disease with varying phenotypic features. A new, common name for these conditions is warranted.