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Background/aims: Mutations in KCNJ11, the gene encoding the Kir6.2 subunit of pancreatic and neuronal KATP channels, are associated with a spectrum of neonatal diabetes diseases., Methods: Variant screening was used to identify the cause of neonatal diabetes, and continuous glucose monitoring was used to assess effectiveness of sulfonylurea treatment. Electrophysiological analysis of variant KATP channel function was used to determine molecular basis., Results: We identified a previously uncharacterized KCNJ11 mutation, c.988T>C [p.Tyr330His], in an Italian child diagnosed with sulfonylurea-resistant permanent neonatal diabetes and developmental delay (intermediate DEND). Functional analysis of recombinant KATP channels reveals that this mutation causes a drastic gain-of-function, due to a reduction in ATP inhibition. Further, we demonstrate that the Tyr330His substitution causes a significant decrease in sensitivity to the sulfonylurea, glibenclamide., Conclusions: In this subject, the KCNJ11 (c.988T>C) mutation provoked neonatal diabetes, with mild developmental delay, which was insensitive to correction by sulfonylurea therapy. This is explained by the molecular loss of sulfonylurea sensitivity conferred by the Tyr330His substitution and highlights the need for molecular analysis of such mutations., (© 2022 S. Karger AG, Basel.)

Aim: Our aim was to investigate the relationships between the degree of IGF2 methylation and the metabolic status in obese children and adolescents., Subjects and Methods: Eighty-five obese subjects aged 11.6 ± 2.1 years were studied. Anthropometry, metabolic parameters, blood pressure and body composition were assessed. DNA methylation analysis was performed by restriction enzyme digestion assay. The study population was subdivided into two groups according to the percentage of IGF2 cytidine-guanosine (CpG) island methylation., Results: Twenty-two subjects showed intermediate methylation (a percentage of CpG site methylation comprised between 10 and 60%), 56 were hypomethylated (percentage of methylation lower than 10%), and only 1 showed a high rate of hypermethylation (percentage of methylation above 60%). Children with intermediate methylation showed significantly higher levels of triglycerides (107.6 ± 41.99 vs. 76.6 ± 30.18 mg/dl, p < 0.005) and a higher triglyceride/high-density lipoprotein-cholesterol ratio (2.23 ± 0.98 vs. 1.79 ± 0.98, p < 0.02) compared with hypomethylated children., Conclusions: These preliminary findings show for the first time a relationship between IGF2 methylation pattern and lipid profile in obese children. Although the correlation does not imply causation, if our findings are confirmed in further studies, IGF2 methylation might represent an epigenetic marker of metabolic risk., (Copyright © 2013 S. Karger AG, Basel.)

Background/aims: Elevated thyroid-stimulating hormone (TSH) concentrations in association with normal/slightly elevated free triiodothyronine (fT(3)) and/or free thyroxine (fT(4)) have been consistently found in obese children. To examine relationships between adiposity, insulin sensitivity, and TSH, fT(3) and fT(4)., Methods: 240 overweight/obese prepubertal children were studied. Fasting TSH, fT(3), fT(4), glucose, insulin, C-peptide, lipids, leptin and adiponectin were evaluated. Insulin sensitivity and resistance were estimated [quantitative insulin check index (QUICKI), insulin sensitivity index (ISI), and hepatic insulin resistance index]. Body fat was measured by dual-energy X-ray absorptiometry. The central obesity index was calculated as the ratio of fat tissue in the trunk region to fat tissue in the leg region., Results: The multiple regression analysis with age, gender and measures of fatness as covariates showed that QUICKI was the only significant negative predictor of TSH and central obesity index the strongest positive predictor of fT(3), in association with either age or hepatic insulin resistance index, and that the only positive determinant of fT(4) was hepatic insulin resistance index., Conclusions: Reduced insulin sensitivity is associated with augmented TSH and fT(4), while progressive central fat accumulation is strictly related to a parallel increase in fT(3) levels, independently from total body fat. Further studies are needed to understand mechanisms linking thyroid function to insulin sensitivity and body composition in obese children., (Copyright © 2012 S. Karger AG, Basel.)

Aim: To evaluate if insulin resistance (IR) and metabolic syndrome (MS) were associated with poor cardiovascular fitness in very obese prepubertal Italian subjects., Methods: Children referred to the Endocrinology and Diabetes Unit of Bambino Gesù Children's Hospital underwent an OGTT with glucose and insulin assays. QUICKI, ISI and HOMA-IR were calculated. Total and HDL cholesterol, triglycerides and percentage of body fat (DEXA) were determined. Cardiovascular fitness (maximal treadmill time) was evaluated using a treadmill protocol. The MS was defined as having 3 or more of following risk factors: obesity, impaired glucose tolerance, high blood pressure, low HDL-cholesterol, high triglycerides., Results: Fifty-five very obese prepubertal Italian children were enrolled in the study. Unadjusted correlation revealed maximal treadmill time negatively related to fasting insulin (r = -0.53, p < 0.0001) and HOMA-IR (r = -0.57, p < 0.0001) and positively to QUICKI (r = 0.51, p < 0.0001) and ISI (r = 0.46, p = 0.0035). These relationships remained significant when in multivariate analysis age, gender, BMI SD and body composition were accounted for (all p < 0.01). The presence of the MS was independently associated with maximal treadmill time., Conclusion: Poorcardiovascular fitness, IR and MS were independently related, suggesting that the relationship between fitness and insulin action develops early in life., (Copyright 2008 S. Karger AG, Basel.)

Until 1995, the etiology of 'neonatal' diabetes was totally unknown. In about a decade, mutations in 8 different genes (IPF1, EIF2AK3, GK, FOXP3, KCNJ11, ABCC8, PTF1A and GLIS3) have been discovered in patients with the permanent form of the disease, and 3 genetic abnormalities (defects in the paternally imprinted chromosomal region 6q24 and 'mild' activating mutations in KCNJ11 or ABCC8) have been detected in subjects with transient neonatal diabetes. Together with the advances in the understanding of the pathophysiology of this condition, clearly different from type 1 diabetes, also the temporal criterion by which one clinically defines a patient as being affected by neonatal diabetes has changed. In 1995, neonatal diabetes was defined as hyperglycemia that requires insulin treatment and occurs during the first month of life. In some patients with defects of KCNJ11, ABCC8 or EIF2AK3 genes however, diabetes can present at 6 months of age and beyond. It is now time to adopt a new definition in order to avoid the confusion originating by the misuse of the term 'neonatal'. I would suggest monogenic diabetes of infancy, which includes both the permanent and the transient types, irrespectively of the mechanism of disease.