Enhancing fetal outcomes in GCK-MODY pregnancies: a precision medicine approach via non-invasive prenatal GCK mutation detection.

Background: Mutations in the GCK gene cause Maturity Onset Diabetes of the Young (GCK-MODY) by impairing glucose-sensing in pancreatic beta cells. During pregnancy, managing this type of diabetes varies based on fetal genotype. Fetuses carrying a GCK mutation can derive benefit from moderate maternal hyperglycemia, stimulating insulin secretion in fetal islets, whereas this may cause macrosomia in wild-type fetuses. Modulating maternal glycemia can thus be viewed as a form of personalized prenatal therapy, highly beneficial but not justifying the risk of invasive testing. We therefore developed a monogenic non-invasive prenatal diagnostic (NIPD-M) test to reliably detect the transmission of a known maternal GCK mutation to the fetus. Methods: A small amount of fetal circulating cell-free DNA is present in maternal plasma but cannot be distinguished from maternal cell-free DNA. Determining transmission of a maternal mutation to the fetus thus implies sequencing adjacent polymorphisms to determine the balance of maternal haplotypes, the transmitted haplotype being over-represented in maternal plasma. Results: Here we present a series of such tests in which fetal genotype was successfully determined and show that it can be used to guide therapeutic decisions during pregnancy and improve the outcome for the offspring. We discuss several potential hurdles inherent to the technique, and strategies to overcome these. Conclusion: Our NIPD-M test allows reliable determination of the presence of a maternal GCK mutation in the fetus, thereby allowing personalized in utero therapy by modulating maternal glycemia, without incurring the risk of miscarriage inherent to invasive testing.

Atypical diabetes with spontaneous remission associated with systemic lupus erythematosus in an adolescent girl of African ancestry, a case report.

BACKGROUND: New-onset diabetes in youth encompasses type 1 diabetes, type 2 diabetes, monogenic diabetes, and rarer subtypes like Type B insulin resistance syndrome and ketosis-prone atypical diabetes in African populations. Some cases defy classification, posing management challenges. Here, we present a case of a unique, reversible diabetes subtype. CASE PRESENTATION: We describe an adolescent African girl recently diagnosed with systemic lupus erythematosus. At age 15, she presented with ketoacidosis, HbA1c of 108.7 mmol/mol (12.1%), and positive anti-insulin antibodies. Initially diagnosed with type 1 diabetes, insulin was prescribed. Due to the presence of obesity and signs of insulin resistance, we added metformin. Concurrently, she received treatment for lupus with hydroxychloroquine, mycophenolate mofetil, and prednisone. After discharge, she stopped insulin due to cultural beliefs. Five months later, her glycemia and HbA1c normalized (37 mmol/mol or 5.5%) without insulin, despite corticosteroid therapy and weight gain. Autoantibodies normalized, and lupus activity decreased. Genetic testing for monogenic diabetes was negative, and the type 1 genetic risk score was exceptionally low. CONCLUSIONS: We present a complex, reversible diabetes subtype. Features suggest an autoimmune origin, possibly influenced by overlapping HLA risk haplotypes with lupus. Lupus treatment or immunomodulation may have impacted diabetes remission. Ancestry-tailored genetic risk scores are currently designed to improve diagnostic accuracy.

Noninvasive prenatal diagnosis of Mendelian disorders for consanguineous couples by relative genotype dosage.

Noninvasive prenatal diagnosis relies on the presence in maternal blood of circulating cell-free fetal DNA released by apoptotic trophoblast cells. Widely used for aneuploidy screening, it can also be applied to monogenic diseases (NIPD-M) in case of known parental mutations. Due to the confounding effect of maternal DNA, detection of maternal or biparental mutations requires relative haplotype dosage (RHDO), a method relying on the presence of SNPs that are heterozygous in one parent and homozygous in the other. Unavoidably, there is a risk of test failure by lack of such informative SNPs, an event particularly likely for consanguineous couples who often share common haplotypes in regions of identity-by-descent. Here we present a novel approach, relative genotype dosage (RGDO) that bypasses this predicament by directly assessing fetal genotype with SNPs that are heterozygous in both parents (frequent in regions of identity-by-descent). We show that RGDO is as sensitive as RHDO and that it performs well over a large range of fetal fractions and DNA amounts, thereby opening NIPD-M to most consanguineous couples. We also report examples of couples, consanguineous or not, where combining RGDO and RHDO allowed a diagnosis that would not have been possible with only one approach.

[Monogenic diabetes : a pioneer in precision medicine management]. / Diabète monogénique : pionnier dans la prise en charge par la médecine de précision.

Diabetes mellitus in children is subdivided into several categories depending on the underlying pathological mechanism. Type 1 diabetes is due to the autoimmune destruction of pancreatic beta-cells, type 2 diabetes to progressive impairment in insulin secretion or insulin sensitivity, and monogenic diabetes due to genetic abnormalities, impairing insulin secretion. In monogenic diabetes, genetic defects result in pancreatic or beta-cell defects (abnormal function or destruction), resulting in neonatal or MODY (Maturity-Onset Diabetes of the Young) diabetes, depending on the age of onset. The identification of monogenic diabetes is crucial as it allows the initiation of targeted and personalized treatment.

Le diabète sucré de l'enfant est subdivisé en plusieurs catégories en fonction du mécanisme pathologique sous-jacent : de type 1 par destruction autoimmune des cellules bêta du pancréas, de type 2 par perte progressive d'une sécrétion adéquate ou de sensibilité à l'insuline et monogénique par anomalie génétique perturbant la sécrétion d'insuline. Dans ce dernier, les anomalies génétiques entraînent des défauts du développement du pancréas ou de la cellule bêta (anomalie de fonction ou destruction), menant à un diabète néonatal ou un diabète MODY (Maturity-Onset Diabetes of the Young) en fonction de l'âge d'apparition. L'identification du diabète monogénique est primordiale puisqu'elle permet l'instauration d'un traitement ciblé et personnalisé.

[Obesity in infancy: new precision treatment]. / Obésité infantile : nouveautés thérapeutiques ciblées.

Obesity is a chronical disease, which leads to multiple short- and long-term complications. 4% of Swiss children and adolescents are obese. A prompt diagnosis and multicomponent lifestyle intervention is mandatory to avoid persistence of the disease into adulthood. Growth and BMI charts are still the essential tools to diagnose and define the etiology of obesity. A precocious and severe obesity, accompanied by hyperphagia, will raise the suspicion of monogenic obesity. The precise molecular diagnosis enables in some patients the use of a specific treatment. Leptine in case of LEP gene defects, or setmelanotide when the affected gene is part of the MC4R signaling pathway (LEPR, POMC, PCSK1).

L'obésité est une maladie chronique, associée à de multiples complications à court et à long termes, présente chez 4 % des enfants et adolescents en Suisse. Un dépistage et une intervention multidisciplinaire précoces sont essentiels pour éviter la persistance de la maladie à l'âge adulte. Les courbes de croissance et de l'IMC sont les outils indispensables pour repérer la maladie et orienter l'étiologie. Ainsi, une obésité d'apparition précoce, de caractère sévère et accompagnée d'une hyperphagie oriente le clinicien vers le diagnostic d'obésité monogénique. Un diagnostic moléculaire précis permet de connaître le gène défectueux et offre, dans certains cas, un traitement ciblé très efficace pour le patient : la leptine en cas de mutation du gène LEP, ou le setmélanotide dans les défauts de la voie de signalisation du MC4R (LEPR, POMC, PCSK1).

Atypical familial diabetes associated with a novel NEUROD1 nonsense variant.

OBJECTIVES: We aimed to identify the origin of atypical diabetes in a family with four generations of diabetes from South Asia. The family members showed different clinical phenotypes. Members of generation one to three were presumed to have type 2 diabetes and generation four to have type 1 diabetes. CASE PRESENTATION: We performed a genetic analysis of the family using targeted high throughput sequencing. CONCLUSIONS: We identified a novel nonsense variant in the neurogenic differentiation 1 (NEUROD1) gene, co-segregating with diabetes. The variant was located in the DNA-binding domain, altering a protein residue that was very well conserved among different species.

Co-segregation analysis and functional trial in vivo of candidate genes for monogenic diabetes.

INTRODUCTION: The aim of this study was to perform familial co-segregation analysis and functional trial in vivo during mixed meal tolerance test (MMTT) of novel variants in diabetes candidate genes. RESEARCH DESIGN AND METHODS: It is a continuation of the project "Genetic diabetes in Lithuania" with the cohort of 1209 patients with diabetes. Prior screening for autoimmune markers confirmed type 1 diabetes (T1D) diagnosis in 88.1% (n=1065) of patients, and targeted next-generation sequencing identified 3.5% (n=42) pathogenic variants in MODY genes. Subsequently, 102 patients were classified as having diabetes of unknown etiology. 12/102 were found to have novel variants in potential diabetes genes (RFX2, RREB1, SLC5A1 (3 patients with variants in this gene), GCKR, MC4R, CASP10, TMPRSS6, HGFAC, DACH1, ZBED3). Co-segregation analysis and MMTT were carried out in order to study beta-cell function in subjects with specific variants. RESULTS: MMTT analysis showed that probands with variants in MC4R, CASP10, TMPRSS6, HGFAC, and SLC5A1 (c.1415T>C) had sufficient residual beta-cell function with stimulated C-peptide (CP) >200 pmol/L. Seven individuals with variants in RFX2, RREB1, GCKR, DACH1, ZBED3 and SLC5A1 (c.1415T>C, and c.932A>T) presented with complete beta-cell failure. No statistical differences were found between patients with sufficient CP production and those with complete beta-cell failure when comparing age at the onset and duration of diabetes. Nineteen family members were included in co-segregation analysis; no diabetes cases were reported among them. Only in patient with the variant c.1894G>A in RFX2 gene, none of the family members were affected by proband's variant. CONCLUSIONS: Functional beta-cell study in vivo allowed to select five most probable genes for monogenic diabetes. Familial co-segregation analysis showed that novel variant in RFX2 gene could be a possible cause of diabetes. Future functional analysis in vitro is necessary to support or rule out the genetic background as a cause of diabetes.

Pancreatic beta-cell function dynamics in youth with GCK, HNF1A, and KCNJ11 genes mutations during mixed meal tolerance test.

OBJECTIVE: The aims were (1) to assess beta-cell function in GCK diabetes patients over 2-year period; (2) to evaluate the dynamics of beta-cell function in HNF1A and KCNJ11 patients after treatment optimization; using mixed meal tolerance test (MMTT) as a gold standard for non-invasive beta-cell function assessment. RESEARCH DESIGN AND METHODS: Twenty-two GCK diabetes patients, 22 healthy subjects, 4 patients with HNF1A and 2 with KCNJ11 were recruited. Firstly, beta-cell function was compared between GCK patients versus controls; the dynamics of beta-cell function were assessed in GCK patients with two MMTTs in 2-year period. Secondly, the change of beta-cell function was evaluated in HNF1A and KCNJ11 patients after successful treatment optimization in 2-year period. RESULTS: GCK diabetes patients had lower area under the curve (AUC) of C-peptide (CP), average CP and peak CP compared to controls. Also, higher levels of fasting, average, peak and AUC of glycemia during MMTT were found in GCK patients compared to healthy controls. No significant changes in either CP or glycemia dynamics were observed in GCK diabetes group comparing 1st and 2nd MMTTs. Patients with HNF1A and KCNJ11 diabetes had significantly improved diabetes control 2 years after the treatment was optimized (HbA1c 7.1% vs. 5.9% [54 mmol/mol vs. 41 mmol/mol], respectively, p = 0.028). Higher peak CP and lower HbA1c were found during 2nd MMTT in patients with targeted treatment compared to the 1st MMTT before the treatment change. CONCLUSION: In short-term perspective, GCK diabetes group revealed no deterioration of beta-cell function. Individualized treatment in monogenic diabetes showed improved beta-cell function.

Loss of Nexmif results in the expression of phenotypic variability and loss of genomic integrity.

We identified two NEXMIF variants in two unrelated individuals with non-autoimmune diabetes and autistic traits, and investigated the expression of Nexmif in mouse and human pancreas and its function in pancreatic beta cells in vitro and in vivo. In insulin-secreting INS-1E cells, Nexmif expression increased strongly in response to oxidative stress. CRISPR Cas9-generated Nexmif knockout mice exhibited a reduced number of proliferating beta cells in pancreatic islets. RNA sequencing of pancreatic islets showed that the downregulated genes in Nexmif mutant islets are involved in stress response and the deposition of epigenetic marks. They include H3f3b, encoding histone H3.3, which is associated with the regulation of beta-cell proliferation and maintains genomic integrity by silencing transposable elements, particularly LINE1 elements. LINE1 activity has been associated with autism and neurodevelopmental disorders in which patients share characteristics with NEXMIF patients, and can cause genomic instability and genetic variation through retrotransposition. Nexmif knockout mice exhibited various other phenotypes. Mortality and phenotypic abnormalities increased in each generation in both Nexmif mutant and non-mutant littermates. In Nexmif mutant mice, LINE1 element expression was upregulated in the pancreas, brain, and testis, possibly inducing genomic instability in Nexmif mutant mice and causing phenotypic variability in their progeny.

Hepatic non-parenchymal S100A9-TLR4-mTORC1 axis normalizes diabetic ketogenesis.

Unrestrained ketogenesis leads to life-threatening ketoacidosis whose incidence is high in patients with diabetes. While insulin therapy reduces ketogenesis this approach is sub-optimal. Here, we report an insulin-independent pathway able to normalize diabetic ketogenesis. By generating insulin deficient male mice lacking or re-expressing Toll-Like Receptor 4 (TLR4) only in liver or hepatocytes, we demonstrate that hepatic TLR4 in non-parenchymal cells mediates the ketogenesis-suppressing action of S100A9. Mechanistically, S100A9 acts extracellularly to activate the mechanistic target of rapamycin complex 1 (mTORC1) in a TLR4-dependent manner. Accordingly, hepatic-restricted but not hepatocyte-restricted loss of Tuberous Sclerosis Complex 1 (TSC1, an mTORC1 inhibitor) corrects insulin-deficiency-induced hyperketonemia. Therapeutically, recombinant S100A9 administration restrains ketogenesis and improves hyperglycemia without causing hypoglycemia in diabetic mice. Also, circulating S100A9 in patients with ketoacidosis is only marginally increased hence unveiling a window of opportunity to pharmacologically augment S100A9 for preventing unrestrained ketogenesis. In summary, our findings reveal the hepatic S100A9-TLR4-mTORC1 axis in non-parenchymal cells as a promising therapeutic target for restraining diabetic ketogenesis.

Precision medicine in diabetes: A non-invasive prenatal diagnostic test for the determination of fetal glucokinase mutations.

Hyperglycemia caused by mutations in the glucokinase gene, GCK, is the most common form of monogenic diabetes. Prenatal diagnosis is important, as it impacts on treatment. This study reports a monogenic non-invasive prenatal diagnostic (NIPD-M) test on cell-free DNA in maternal plasma using the relative haplotype dosage. In three pregnancies of two families with known maternal GCK mutations, the fetal genotype was determined unambiguously already at 12 weeks of gestation. In summary, proof is provided of the feasibility for NIPD-M in GCK diabetes.

Kinetics of C-peptide during mixed meal test and its value for treatment optimization in monogenic diabetes patients.

AIM: The mixed meal tolerance test (MMTT) is a gold standard for evaluating beta-cell function. There is limited data on MMTT in monogenic diabetes (MD). Therefore, we aimed to analyze plasma C-peptide (CP) kinetics during MMTT in young MODY and neonatal diabetes patients as a biomarker for beta-cell function. METHODS: We included 41 patients with MD diagnosis (22 GCK, 8 HNF1A, 3 HNF4A, 4 KCNJ11, 2 ABCC8, 1 INS, 1 KLF11). Standardized 3-hour MMTT with glycemia and plasma CP measurements were performed for all individuals. Pancreatic beta-cell response was assessed by the area under the curve CP (AUCCP), the baseline CP (CPBase) and the peak CP (CPmax). Threshold points of CPBase, CP90, CPmax and CPAUC were determined from analysis of ROC curves. RESULTS: GCK diabetes patients had significantly higher AUCCP, CPBase and CPmax compared to HNF4A and KCNJ11 patients. In HNF4A, KCNJ11 and ABCC8 patients with all CP levels < 200 pmol/L, the treatment change attempt to sulfonylurea agent was unsuccessful. The ROC analysis showed that CP baseline threshold equal or higher to 133.5 pmol/L could be used to predict successful switch to oral agents. CONCLUSION: A pretreatment challenge with MMTT might be used to guide the optimal treatment after molecular diagnosis of MD.

[MODY type diabetes: an often-misunderstood entity]. / Diabète de type MODY : une entité souvent méconnue.

MODY diabetes, for Maturity Onset Diabetes of the Young, is a form of monogenic diabetes characterized by a typical onset before the age of 25 years, the lack of autoimmunity against the b cells of the pancreas, a preserved ß cells function and an autosomal dominant mode of inheritance. This type of diabetes constitutes 2 to 5% of all cases of diabetes but remains often undiagnosed. Nearly 15 MODY subtypes have been identified to date. The 3 most common subtypes are caused by mutations in the genes encoding glucokinase, HNF1a and HNF4a, and account for approximately 80% of all MODY cases. Carrying out a genetic test can thus make it possible to make the diagnosis of MODY diabetes and to set up an appropriate treatment. In this article we will discuss these 3 main MODY sub-type, although there are other forms, which may be characterized by associated specific organ damage.

Le diabète Maturity Onset Diabetes of the Young (MODY) est une forme de diabète monogénique se caractérisant par une apparition typique avant l'âge de 25 ans, l'absence d'autoimmunité contre les cellules ß du pancréas, une fonction préservée des cellules ß et un mode de transmission autosomique dominant. Ce type de diabète constitue 2 à 5 % de tous les cas de diabètes, mais reste souvent non diagnostiqué. Près de 15 sous-types sont, à ce jour, identifiés. Les 3 les plus fréquents sont causés par des mutations des gènes codant pour la glucokinase, HNF1α et HNF4α, qui représentent environ 80 % des cas de MODY. La réalisation d'un test génétique peut ainsi permettre de poser le diagnostic de MODY et mettre en place un traitement approprié. Dans cet article nous discutons de ces 3 sous-types principaux de MODY, bien qu'il existe d'autres formes plus rares pouvant se caractériser par des atteintes d'organes spécifiques associées.

Systematic Genetic Study of Youth With Diabetes in a Single Country Reveals the Prevalence of Diabetes Subtypes, Novel Candidate Genes, and Response to Precision Therapy.

Identifying gene variants causing monogenic diabetes (MD) increases understanding of disease etiology and allows for implementation of precision therapy to improve metabolic control and quality of life. Here, we aimed to assess the prevalence of MD in youth with diabetes in Lithuania, uncover potential diabetes-related gene variants, and prospectively introduce precision treatment. First, we assessed all pediatric and most young-adult patients with diabetes in Lithuania (n = 1,209) for diabetes-related autoimmune antibodies. We then screened all antibody-negative patients (n = 153) using targeted high-throughput sequencing of >300 potential candidate genes. In this group, 40.7% had MD, with the highest percentage (100%) in infants (diagnosis at ages 0-12 months), followed by those diagnosed at ages >1-18 years (40.3%) and >18-25 years (22.2%). The overall prevalence of MD in youth with diabetes in Lithuania was 3.5% (1.9% for GCK diabetes, 0.7% for HNF1A, 0.2% for HNF4A and ABCC8, 0.3% for KCNJ11, and 0.1% for INS). Furthermore, we identified likely pathogenic variants in 11 additional genes. Microvascular complications were present in 26% of those with MD. Prospective treatment change was successful in >50% of eligible candidates, with C-peptide >252 pmol/L emerging as the best prognostic factor.

Factors Affecting Cardiovascular Risk in Children, Adolescents, and Young Adults with Type 1 Diabetes.

Cardiovascular risk and obesity are becoming major health issues among individuals with type 1 diabetes (T1D). The aim of this study was to evaluate cardiovascular risk factors and obesity in youth with T1D in Lithuania. Methods. 883 patients under 25 years of age with T1D for at least 6 months were investigated. Anthropometric parameters, blood pressure, and microvascular complications were evaluated, and the lipid profile and HbA1c were determined for all patients. Results. Study subjects' mean HbA1c was 8.5 ± 2%; 19.5% were overweight and 3.6% obese. Hypertension and dyslipidemia were diagnosed in 29.8% and 62.6% of participants, respectively. HbA1c concentration was directly related to levels of total cholesterol (r = 0.274, p < 0.001), LDL (r = 0.271, p < 0.001), and triglycerides (r = 0.407, p < 0.001) and inversely associated with levels of HDL (r = 0.117, p = 0.001). Prevalence of dyslipidemia increased with duration of diabetes (p < 0.05). Hypertension was more prevalent in overweight and obese compared to normal-weight patients (40.6 and 65.6 vs. 25.6%, respectively, p < 0.001). Frequency of microvascular complications was higher among patients with dyslipidemia (27.2 vs. 18.8%, p = 0.005) and among those with hypertension (25.9 vs. 23.2%, p < 0.001). Conclusion. The frequency of cardiovascular risk factors is high in youth with T1D and associated with diabetes duration, obesity, and metabolic control.