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Abstract Background Individuals with maturity‐onset diabetes of the young (MODY) are often misdiagnosed as type 1 or type 2 diabetes and receive inappropriate care. We aimed to investigate the characteristics and treatment of all MODY types in a multicenter, real‐world setting. Methods Individuals with MODY from the diabetes prospective follow‐up (DPV) registry were studied. We compared clinical parameters during the first year of diabetes and the most recent treatment year after MODY diagnosis. Results A total of 1640 individuals were identified with GCK‐MODY (n = 941) and HNF1A‐MODY (n = 417) as the most frequent types. Among these, 912 individuals were available with information during the first and the most recent treatment year (median duration of follow‐up: 4.2 years [2.6–6.6]). Positive beta cell autoantibodies were present in 20.6% (15.2% IAA). Median age at diagnosis ranged from 9.9 years in GCK‐MODY (Q1–Q3: 6.2–13.1 years) and INS‐MODY (2.7–13.7 years) to 14.3 years (5.0–17.1) in KCNJ11‐MODY. Frequency of oral antidiabetic agents (OAD) use increased and insulin decreased in HNF4A‐MODY (OAD: 18% to 39%, insulin: 34% to 23%) and in HNF1A‐MODY (OAD: 18% to 31%, insulin: 35% to 25%). ABCC8‐MODY was characterized by a decrement in nonpharmacological treatment (26% to 16%) and “insulin only” treatment (53% to 42%), while the proportion of individuals treated with OAD but no insulin increased from 0% to 21%. Conclusions Our results indicate that some teams caring for individuals with MODY are hesitant with regard to current recommendations. Registries are an essential source of information and provide a basis for discussing treatment guidelines for MODY.

Abstract Early treatment of neonatal diabetes with sulfonylureas has been proven to produce marked improvements of neurodevelopment, beside the demonstrated efficacy on glycemic control. Several barriers still prevent an early treatment in preterm babies including the limited availability of suitable galenic form of glibenclamide. We adopted oral glibenclamide suspension (Amglidia) for the early treatment of neonatal diabetes due to an homozygous variant of KCNJ11 gene c.10C>T [p.Arg4Cys] in an extremely preterm infant born at 26 + 2 weeks' of gestational age. After ~6 weeks of insulin treatment with a low glucose intake (4.5 g/kg/day), the infant was switched to Amglidia 6 mg/ml diluted in maternal milk, via nasogastric tube (0.2 mg/kg/day) progressively reduced to 0.01 mg/kg/day (after ~3 months). While on glibenclamide, the patient exhibited a mean daily growth of 11 g/kg/day. The treatment was suspended at month 6 of birth (weight 4.9 kg [5th–10th centile], M3 of c.a.) for normalization of glucose profile. During the treatment, the patient exhibited a stable glucose profile within the range of 4–8 mmol/L in the absence of hypo or hyperglycemic episodes with 2–3 blood glucose tests per day. The patient was diagnosed with retinopathy of prematurity Stade II in Zone II without plus disease at 32 weeks, with progressive regression and complete retinal vascularization at 6 months of birth. Amglidia could be regarded as the specific treatment for neonatal diabetes even in preterm babies due to its beneficial effect on the metabolic and neurodevelopmental side.

Abstract Maturity‐onset of diabetes of the young (MODY) are monogenic forms of diabetes characterized by early onset diabetes with autosomal dominant inheritance. Since its first description about six decades ago, there have been significant advancements in our understanding of MODY from clinical presentations to molecular diagnostics and therapeutic responses. The prevalence of MODY is estimated as at least 1.1–6.5% of the pediatric diabetes population with a high degree of geographic variability that might arise from several factors in the criteria used to ascertain cases. GCK‐MODY, HNF1A‐MODY, and HNF4A‐MODY account for >90% of MODY cases. While some MODY forms do not require treatment (i.e., GCK‐MODY), some others are highly responsive to oral agents (i.e., HNF1A‐MODY). The risk of micro‐ and macro‐vascular complications of diabetes also differ significantly between MODY forms. Despite its high clinical impact, 50–90% of MODY cases are estimated to be misdiagnosed as type 1 or type 2 diabetes. Although there are many clinical features suggestive of MODY diagnosis, there is no single clinical criterion. An online MODY Risk Calculator can be a useful tool for clinicians in the decision‐making process for MODY genetic testing in some situations. Molecular genetic tests with a commercial gene panel should be performed in cases with a suspicion of MODY. Unresolved atypical cases can be further studied by exome or genome sequencing in a clinical or research setting, as available.

ABSTRACT 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.

Abstract Glucokinase‐maturity‐onset diabetes of the young (GCK‐MODY) is often misdiagnosed as other forms of diabetes. A 42‐year‐old pregnant lady with pre‐existing diabetes was treated with insulin during first trimester. Fetal growth restriction was noted since mid‐second trimester. Genetic testing suggested the diagnosis of GCK‐MODY.

Key Clinical Message Wolcott‐Rallison syndrome is a rare genetic syndrome of neonatal diabetes, liver failure, and growth retardation. We present a case with a EIF2AK3 p.(Arg902Ter) mutation, additionally complicated by hypothyroidism, impaired renal function, and exocrine pancreas insufficiency, focusing on clinical management. For its optimization, thorough care of multiple organ systems is needed.

Abstract Background MODY‐NEUROD1 is a rare form of monogenic diabetes caused by mutations in Neuronal differentiation 1 (NEUROD1). Until now, only a few cases of MODY‐NEUROD1 have been reported worldwide and the real contribution of mutations in NEUROD1 in monogenic diabetes and its clinical impact remain unclear. Methods Genomic DNA was isolated from peripheral blood lymphocytes of 25 unrelated Brazilians patients with clinical characteristics suggestive of monogenic diabetes and the screening of the entire coding region of NEUROD1 was performed by Sanger sequencing. Results We identified one novel frameshift deletion (p.Phe256Leufs*2) in NEUROD1 segregating in an autosomal dominant inheritance fashion. Almost 20 years after the first report of NEUROD1‐MODY, only a few families in Europe and Asia had shown mutations in NEUROD1 as the cause of monogenic diabetes. Conclusion To our knowledge, we described the first case of NEUROD1‐MODY in a Latin American family.

Abstract Background Homozygous inactivating GCK mutations have been repeatedly reported to cause severe hyperglycemia, presenting as permanent neonatal diabetes mellitus (PNDM). Conversely, only two cases of GCK homozygous mutations causing mild hyperglycemia have been so far described. We here report a novel GCK mutation (c.1116G>C, p.E372D), in a family with one homozygous member showing mild hyperglycemia. Methods GCK mutational screening was carried out by Sanger sequencing. Computational analyses to investigate pathogenicity and molecular dynamics (MD) were performed for GCK‐E372D and for previously described homozygous mutations associated with mild (n = 2) or severe (n = 1) hyperglycemia, used as references. Results Of four mildly hyperglycemic family‐members, three were heterozygous and one, diagnosed in the adulthood, was homozygous for GCK‐E372D. Two nondiabetic family members carried no mutations. Fasting glucose (p = 0.016) and HbA1c (p = 0.035) correlated with the number of mutated alleles (0–2). In‐silico predicted pathogenicity was not correlated with the four mutations’ severity. At MD, GCK‐E372D conferred protein structure flexibility intermediate between mild and severe GCK mutations. Conclusions We present the third case of homozygous GCK mutations associated with mild hyperglycemia, rather than PNDM. Our in‐silico analyses support previous evidences suggesting that protein stability plays a role in determining clinical severity of GCK mutations.

Most monogenic diabetes is misdiagnosed as either type 1 or type 2 diabetes (T1D/T2D). Few studies have examined the diagnostic challenges from the patients' perspective. This qualitative study aimed to investigate patients' journeys to obtaining a diagnosis of maturity-onset diabetes of the young (MODY) by elucidating the range of factors that can act as barriers and facilitators throughout this process. We recruited participants from the Personalized Diabetes Medicine Program (PDMP) at University of Maryland and used respondent-driven sampling to recruit additional patients. We conducted qualitative phone interviews between October 2016 and June 2017 with nine patients with diagnoses of monogenic diabetes (one HNF4A-MODY, seven GCK-MODY, and one HNF1A-MODY) and one parent of a patient with INS-MODY. Interview data were audio recorded, transcribed, and analyzed both inductively and deductively using thematic content analysis. All patients were female, with a mean age of 35 (range: 7-67 years). The amount of time these patients were misdiagnosed ranged from a few months to 41 years. We identified barriers and facilitators in three broad themes: (a) patient-related (nature of MODY symptoms, perceived test utility, individual personality); (b) provider-related (provider awareness and knowledge, provider communication); and (c) healthcare system-related (cost of testing, access to knowledgeable providers, patient education, and support resources). The diverse range of barriers and facilitators reiterates the complexity of the MODY diagnostic process. Limited awareness and knowledge of MODY from healthcare professionals and patients themselves account for most diagnostic delays described in this study. Efforts to promote awareness of MODY and expand access to screening and testing may result in quicker diagnosis and ensure the downstream benefits of proper treatment., (© 2020 National Society of Genetic Counselors.)