Clinical Characteristics and Diagnostic Criteria of Maturity-Onset Diabetes Of The Young (MODY) due to Molecular Anomalies of the HNF1A Gene

Context: The diagnosis of maturity-onset diabetes of the young type 3 (MODY3), associated with HNF1A molecular abnormalities, is often missed.Objective: The objective of the study was to describe the phenotypes of a large series of MODY3 patients and to reassess parameters that may improve its diagnosis. Design, Setting, and Patients: This retrospective multicenter study included 487 unrelated patients referred because of suspicion of MODY3. Genetic analysis identified 196 MODY3 and 283 non-MODY3 cases. Criteria associated with MODY3 were assessed by multivariate analysis. The capacity of the model to predict MODY3 diagnosis was assessed by the area under the receiver-operating characteristic curve and was further validated in an independent sample of 851 patients (165 MODY3 and 686 non-MODY3). Results: In the MODY3 patients, diabetes was revealed by clinical symptoms in 25% of the cases and was diagnosed by screening in the others. Age at diagnosis of diabetes was more than 25 yr in 40% of the MODY3 patients. There was considerable variability and overlap of all assessed parameters in MODY3 and non-MODY3 patients. The best predictive model was based on criteria available at diagnosis of diabetes, including age, body mass index, number of affected generations, presence of diabetes symptoms, and geographical origin. The area under the curve of the receiver-operating characteristic analysis was 0.81. When sensitivity was set to 90%, specificity was 49%. Conclusions: Differential diagnosis between MODY3 and early-onset type 2 diabetes remains difficult. Whether the proposed model will improve the pick-up rate of MODY3 diagnosis needs to be confirmed in independent populations

The Etiological Diagnosis of Diabetes: Still a Challenge for the Clinician

The etiological diagnosis of diabetes conveys many practical consequences for the care of patients, and often of their families. However, a wide heterogeneity in the phenotypes of all diabetes subtypes, including Type 1 diabetes, Type 2 diabetes, and monogenic diabetes, has been reported and contributes to frequent misdiagnoses. The recently revised WHO classification of diabetes mellitus includes two new classes, namely “hybrid forms” and “unclassified diabetes”, which also reflect the difficulties of this etiological diagnosis. During the last years, many studies aiming at identifying homogenous subgroups on refined phenotypes have been reported. Ultimately, such subtyping may improve the diagnosis, prognosis, and treatment of patients on a pathophysiological basis. Here, we discuss the concepts of typical vs. atypical diabetes in the context of autoimmune Type 1 diabetes, Type 2 diabetes, and its monogenic forms. We discuss the contributions of clinical markers, biological tests, particularly islet cell auto-antibodies, and genetics to improving accurate diagnoses. These data support a systematic evaluation of all newly diagnosed diabetes cases

Pregnancy in Women With Monogenic Diabetes due to Pathogenic Variants of the Glucokinase Gene: Lessons and Challenges

International audienceHeterozygous loss-of-function variants of the glucokinase (GCK) gene are responsible for a subtype of maturity-onset diabetes of the young (MODY). GCK-MODY is characterized by a mild hyperglycemia, mainly due to a higher blood glucose threshold for insulin secretion, and an up-regulated glucose counterregulation. GCK-MODY patients are asymptomatic, are not exposed to diabetes long-term complications, and do not require treatment. The diagnosis of GCK-MODY is made on the discovery of hyperglycemia by systematic screening, or by family screening. The situation is peculiar in GCK-MODY women during pregnancy for three reasons: 1. the degree of maternal hyperglycemia is sufficient to induce pregnancy adverse outcomes, as in pregestational or gestational diabetes; 2. the probability that a fetus inherits the maternal mutation is 50% and; 3. fetal insulin secretion is a major stimulus of fetal growth. Consequently, when the fetus has not inherited the maternal mutation, maternal hyperglycemia will trigger increased fetal insulin secretion and growth, with a high risk of macrosomia. By contrast, when the fetus has inherited the maternal mutation, its insulin secretion is set at the same threshold as the mother’s, and no fetal growth excess will occur. Thus, treatment of maternal hyperglycemia is necessary only in the former situation, and will lead to a risk of fetal growth restriction in the latter. It has been recommended that the management of diabetes in GCK-MODY pregnant women should be guided by assessment of fetal growth by serial ultrasounds, and institution of insulin therapy when the abdominal circumference is ≥ 75th percentile, considered as a surrogate for the fetal genotype. This strategy has not been validated in women with in GCK-MODY. Recently, the feasibility of non-invasive fetal genotyping has been demonstrated, that will improve the care of these women. Several challenges persist, including the identification of women with GCK-MODY before or early in pregnancy, and the modalities of insulin therapy. Yet, retrospective observational studies have shown that fetal genotype, not maternal treatment with insulin, is the main determinant of fetal growth and of the risk of macrosomia. Thus, further studies are needed to specify the management of GCK-MODY pregnant women during pregnancy

Pancreatic enzyme replacement therapy in subjects with exocrine pancreatic insufficiency and diabetes mellitus: a real-life, case–control study

International audienceAbstract Background Exocrine pancreatic insufficiency (EPI) can be associated with all types of diabetes. Pancreatic enzyme replacement therapy (PERT) has short and long-term benefits in subjects with EPI, but its effects on diabetes control are uncertain. We aimed to study the effects of PERT initiation on glycemic control in subjects with diabetes and EPI from any cause. Methods In this retrospective study, we compared subjects with EPI and diabetes who were prescribed PERT with subjects with diabetes who had a fecal elastase-1 concentration dosage, but did not receive PERT. The primary outcome was the effect of PERT on hypoglycemia frequency and severity. The secondary outcomes were the effects of PERT on gastro-intestinal disorders, HbA 1c and body mass index (BMI). Results 48 subjects were included in each group. Overall, PERT did not have any significant effect on hypoglycemia frequency or severity, but hypoglycemia frequency tended to decrease in subjects with chronic pancreatitis. While 19% of subjects experienced mild hyperglycemia after PERT initiation, we did not report any keto-acidosis or any other severe adverse event. Gastro-intestinal disorders improved in 80% of subjects treated with PERT, versus in 20% of control subjects ( p = 0.02). Gastro-intestinal disorders improved in 87% of subjects with recommended dosage of PERT, versus in 50% of subjects with underdosage (NS). HbA 1c and BMI evolution did not differ between the groups. Conclusions PERT initiation is safe in subjects with diabetes and EPI. It does not globally decrease hypoglycemia severity of frequency, but is associated with a decrease in gastro-intestinal disorders. Trial registration Retrospectively registered. The database was registered with the Commission Nationale Informatique et Libertés (CNIL), registration number: 2203351v0. The study was approved by the local ethics committee CLEP, registration number: AAA-2023-0904

Tubular proteinuria in patients with HNF1α mutations: HNF1α drives endocytosis in the proximal tubule.

Hepatocyte nuclear factor 1α (HNF1α) is a transcription factor expressed in the liver, pancreas, and proximal tubule of the kidney. Mutations of HNF1α cause an autosomal dominant form of diabetes mellitus (MODY-HNF1A) and tubular dysfunction. To gain insights into the role of HNF1α in the proximal tubule, we analyzed Hnf1a-deficient mice. Compared with wild-type littermates, Hnf1a knockout mice showed low-molecular-weight proteinuria and a 70% decrease in the uptake of β2-microglobulin, indicating a major endocytic defect due to decreased expression of megalin/cubilin receptors. We identified several binding sites for HNF1α in promoters of Lrp2 and Cubn genes encoding megalin and cubilin, respectively. The functional interaction of HNF1α with these promoters was shown in C33 epithelial cells lacking endogenous HNF1α. Defective receptor-mediated endocytosis was confirmed in proximal tubule cells from these knockout mice and could be rescued by transfection of wild-type but not mutant HNF1α. Transfection of human proximal tubule HK2 cells with HNF1α was able to upregulate megalin and cubilin expression and to increase endocytosis of albumin. Low-molecular-weight proteinuria was consistently detected in individuals with HNF1A mutations compared with healthy controls and patients with non-MODY-HNF1A diabetes mellitus. Thus, HNF1α plays a key role in the constitutive expression of megalin and cubilin, hence regulating endocytosis in the proximal tubule of the kidney. These findings provide new insight into the renal phenotype of individuals with mutations of HNF1A

Peptides Derived From Insulin Granule Proteins Are Targeted by CD8 + T Cells Across MHC Class I Restrictions in Humans and NOD Mice

International audienceThe antigenic peptides processed by β-cells and presented through surface HLA class I molecules are poorly characterized. Each HLA variant (e.g., the most common being HLA-A2 and HLA-A3) carries some peptide-binding specificity. Hence, features that, despite these specificities, remain shared across variants may reveal factors favoring β-cell immunogenicity. Building on our previous description of the HLA-A2/A3 peptidome of β-cells, we analyzed the HLA-A3-restricted peptides targeted by circulating CD8+ T cells. Several peptides were recognized by CD8+ T cells within a narrow frequency (1-50/106), which was similar in donors with and without type 1 diabetes and harbored variable effector/memory fractions. These epitopes could be classified as conventional peptides or neoepitopes, generated either via peptide cis-splicing or mRNA splicing (e.g., secretogranin-5 [SCG5]-009). As reported for HLA-A2-restricted peptides, several epitopes originated from β-cell granule proteins (e.g., SCG3, SCG5, and urocortin-3). Similarly, H-2Kd-restricted CD8+ T cells recognizing the murine orthologs of SCG5, urocortin-3, and proconvertase-2 infiltrated the islets of NOD mice and transferred diabetes into NOD/scid recipients. The finding of granule proteins targeted in both humans and NOD mice supports their disease relevance and identifies the insulin granule as a rich source of epitopes, possibly reflecting its impaired processing in type 1 diabetes

Large genomic rearrangements in the hepatocyte nuclear factor-1β (TCF2) gene are the most frequent cause of maturity-onset diabetes of the young type 5

Maturity-onset diabetes of the young (MODY) 5 is caused by mutations in the TCF2 gene encoding the transcription factor hepatocyte nuclear factor-1β. However, in 60% of the patients with a phenotype suggesting MODY5, no point mutation is detected in TCF2. We have hypothesized that large genomic rearrangements of TCF2 that are missed by conventional screening methods may account for this observation. In 40 unrelated patients presenting with MODY5 phenotype, TCF2 was screened for mutations by sequencing. Patients without mutations were then screened for TCF2 rearrangements by the quantitative multiplex PCR of short fluorescent fragments (QMPSF). Among the 40 patients, the overall detection rate was 70%: 18 had point mutations, 9 had whole-gene deletions, and 1 had a deletion of a single exon. Similar phenotypes were observed in patients with mutations and in subjects with large deletions. These results suggest that MODY5 is more prevalent than previously reported, with one-third of the cases resulting from large deletions of TCF2. Because QMPSF is more rapid and cost effective than sequencing, we propose that patients whose phenotype is consistent with MODY5 should be screened first with the QMPSF assay. In addition, other MODY genes should be screened for large genomic rearrangements. © 2005 by the American Diabetes Association

Le Charme de l’Antiquité à nos jours

« Exister sans consister en quoi que ce soit, n’est-ce pas le déroutant, décevant, irritant paradoxe du Charme ? » Cette question de Vladimir Jankélévitch, un des rares penseurs à s’être intéressé au charme, rend compte de la difficulté à saisir et à théoriser une notion au carrefour de plusieurs disciplines. Notion éminemment subjective, le charme contient une part d’inattendu, d’incertain. Il s’oppose à l’habituel et à la routine, aux normes et aux cadres. Il désigne tout ce qui est léger et fugitif, vague et vaporeux, échappant ainsi aux tentatives de théorisation. Il comporte une part de mystère, il est au rebours du prévisible. Il laisse deviner un monde inconnu qui attire et fascine. Il est promesse de nouveauté et d’imprévu ; promesse de plaisir et de bonheur à venir. C’est l’appel du rêve, de l’imaginaire. C’est la porte ouverte vers un possible indéterminé, vers une éventuelle transcendance. Le charme s’impose à nous et nous sommes alors sous le charme d’un sourire, d’une atmosphère, d’un parfum, d’une musique, d’un lieu, d’une personne, d’une œuvre littéraire ou artistique. Mais on ne sait ni pourquoi ni comment. Son étymologie latine confirme son pouvoir de fascination : son étymon carmen désigne tout d’abord une formule rythmée, notamment magique, dans la langue religieuse et juridique, puis renvoie à une parole poétique aux vertus magiques. Le chant enchante… Si la question de la beauté traverse nombre de recherches, la notion de charme, elle, a fait l’objet de très peu d’intérêt, comme toutes les notions qui désignent de l’impalpable, et se trouve ainsi à la marge des recherches scientifiques. L’ouvrage a pour ambition de combler un réel vide dans ce domaine. Il s’organise thématiquement en quatre parties, en rayonnant de l’Antiquité gréco-latine à l’époque contemporaine : après un chapitre liminaire inaugurant la réflexion, le charme est tour à tour étudié dans ses rapports à la musique, à la peinture, dans les paysages ou les personnages littéraires, enfin, dans la chair même des textes