Neonatal diabetes mellitus

Transient Neonatal Diabetes due to a Mutation in KCNJ11 in a Child with Klinefelter Syndrome

Klinefelter syndrome is the most frequent chromosomal aneuploidy in males occurring in about 1 in 660 males. Epidemiological studies have demonstrated increased risk of type 1 diabetes and type 2 diabetes in adults with Klinefelter syndrome. There is only one previous report of neonatal diabetes in a patient with Klinefelter syndrome. We report transient neonatal diabetes due to a pathogenic heterozygous variant in KCNJ11 in a male infant with Klinefelter syndrome. A 78-day old male infant was noted to have sustained hyperglycemia with serum glucose ranging between 148 mg/dL (8.2 mmol/L) and 381 mg/dL (21.2 mmol/L) three days after undergoing a complete repair of an atrioventricular defect. Hemoglobin A1c was 6.6%. The patient was born at term with a birth weight of 2.16 kg following a pregnancy complicated by gestational diabetes that was controlled with diet. The patient was initially started on a continuous intravenous insulin drip and subsequently placed on subcutaneous insulin (glargine, human isophane and regular insulin). Insulin was gradually decreased and eventually discontinued at seven months of age. Chromosomal microarray at 11 weeks of age showed XXY and a panel-based, molecular test for neonatal diabetes revealed a pathogenic heterozygous variant c.685G>A (p.Glu229Lys) in KCNJ11. The patient is now 34 months old and continues to have normal fasting and post-prandial glucose and HbA1C levels. The patient will need prospective follow up for assessment of his glycemic status. To our knowledge this is the second reported case of neonatal diabetes in an infant with Klinefelter syndrome and the first due to a mutation in the KCNJ11 in a patient with Klinefelter syndrome.

Early transition from insulin to sulfonylureas in neonatal diabetes and follow-up: Experience from China

BACKGROUND

Sulfonylurea therapy can improve glycemic control and ameliorate neurodevelopmental outcomes in patients suffering from neonatal diabetes mellitus (NDM) with KCNJ11 or ABCC8 mutations. As genetic testing results are often delayed, it remains controversial whether sulfonylurea treatment should be attempted immediately at diagnosis or doctors should await genetic confirmation.

OBJECTIVE

This study aimed to investigate the effectiveness and safety of sulfonylurea therapy in Chinese NDM patients during infancy before genetic testing results were available.

METHODS

The medical records of NDM patients with their follow-up details were reviewed and molecular genetic analysis was performed. Sulfonylurea transfer regimens were applied in patients diagnosed after May 2010, and glycemic status and side effects were evaluated in each patient.

RESULTS

There were 23 NDM patients from 22 unrelated families, 10 had KCNJ11 mutations, 3 harbored ABCC8 mutations, 1 had INS mutations, 4 had chromosome 6q24 abnormalities, 1 had a deletion at chromosome 1p36.23p36.12, and 4 had no genetic abnormality identified. Sixteen NDM infants were treated with glyburide at an average age of 49 days (range 14-120 days) before genetic confirmation. A total of 11 of 16 (69%) were able to successfully switch to glyburide with a more stable glucose profile. The responsive glyburide dose was 0.51 ± 0.16 mg/kg/d (0.3-0.8 mg/kg/d), while the maintenance dose was 0.30 ± 0.07 mg/kg/d (0.2-0.4 mg/kg/d). No serious adverse events were reported.

CONCLUSIONS

Molecular genetic diagnosis is recommended in all patients with NDM. However, if genetic testing results are delayed, sulfonylurea therapy should be considered before such results are received, even in infants with newly diagnosed NDM.

Neonatal hyperglycemia induces cell death in the rat brain

Several studies have examined neonatal diabetes, a rare disease characterized by hyperglycemia and low insulin levels that is usually diagnosed in the first 6 month of life. Recently, the effects of diabetes on the brain have received considerable attention. In addition, hyperglycemia may perturb brain function and might be associated with neuronal death in adult rats. However, few studies have investigated the damaging effects of neonatal hyperglycemia on the rat brain during central nervous system (CNS) development, particularly the mechanisms involved in the disease. Thus, in the present work, we investigated whether neonatal hyperglycemia induced by streptozotocin (STZ) promoted cell death and altered the levels of proteins involved in survival/death pathways in the rat brain. Cell death was assessed using FluoroJade C (FJC) staining and the expression of the p38 mitogen-activated protein kinase (p38), phosphorylated-c-Jun amino-terminal kinase (p-JNK), c-Jun amino-terminal kinase (JNK), protein kinase B (Akt), phosphorylated-protein kinase B (p-Akt), glycogen synthase kinase-3β (Gsk3β), B-cell lymphoma 2 (Bcl2) and Bcl2-associated X protein (Bax) protein were measured by Western blotting. The main results of this study showed that the metabolic alterations observed in diabetic rats (hyperglycemia and hypoinsulinemia) increased p38 expression and decreased p-Akt expression, suggesting that cell survival was altered and cell death was induced, which was confirmed by FJC staining. Therefore, the metabolic conditions observed during neonatal hyperglycemia may contribute to the harmful effect of diabetes on the CNS in a crucial phase of postnatal neuronal development.

Understanding childhood diabetes mellitus: new pathophysiological aspects

Diabetes mellitus (DM) is not a single disease, but several pathophysiological conditions where synthesis, release, and/or action of insulin are disturbed. A progressive autoimmune/autoinflammatory destruction of islet cells is still considered the main pathophysiological event in the development of T1DM, but there is evidence that T1DM itself is a heterogeneous disease. More than 50 gene regions are closely associated with T1DM and a variety of epigenetic factors and metabolic patterns have been characterized, which may play a role in the development of T1DM. The pathogenesis and genetics of type 2 DM (T2DM) are distinct from T1DM. Genes associated with T2DM are distinct from those in T1DM. Characteristic metabolic patterns, different from those in T1DM were reported in T2DM, and some children with T2DM also express islet-antibodies. Huge progress has been made in the characterization of other specific types of DM, which had been considered very rare before. The molecular clarification of maturity-onset diabetes of the young (MODY) has greatly improved our understanding of the pathophysiology of DM. There are genetic overlaps between T2DM and monogenetic DM. Neonatal DM has been shown to be monogenetic in most cases, and genetic elucidation leads to more precise and individualized therapies. Cystic fibrosis related DM (CFRDM) should be considered a genuine part of cystic fibrosis, and not a complication, since pancreatic fibrosis does not sufficiently explain the pathophysiology of CFRDM. Disturbances of cystic fibrosis transmembrane conductance regulator (CFTR) as well as autoimmunity are involved in the pathogenesis of CFRDM.

Glycemic control indicator levels at diagnosis of neonatal diabetes mellitus: Comparison with other types of insulin-dependent diabetes mellitus

BACKGROUND

Neonatal diabetes mellitus (NDM) is a monogenic insulin-dependent diabetes that develops within 6 months of age. The progression of hyperglycemia until diagnosis is unknown. Glycemic control indicators at diagnosis are useful to estimate the extent and duration of hyperglycemia. We recently established that age-adjusted glycated albumin (GA) is a useful indicator of glycemic control, regardless of age.

OBJECTIVE

To compare the levels of various glycemic control indicators at diagnosis between NDM and other types of insulin-dependent diabetes mellitus.

PATIENTS AND METHODS

We included 8 patients with NDM, 8 with fulminant type 1 diabetes (FT1D), and 24 with acute-onset autoimmune type 1 diabetes (T1AD). Plasma glucose, glycated hemoglobin (HbA1c), GA, and age-adjusted GA (calculated as previously reported) were measured and compared.

RESULTS

There were no significant differences in the plasma glucose levels of the group of patients with NDM and those with FT1D or T1AD. HbA1c and GA levels in the NDM group were not significantly different from those in the FT1D group, and both indicators were lower than those in the T1AD group. Age-adjusted GA levels in the NDM group did not differ significantly from those in the T1AD group, but were higher than those in the FT1D group.

CONCLUSIONS

These findings suggest that the time-course of plasma glucose elevation in NDM until diagnosis is similar to that in T1AD. In addition, the high age-adjusted GA value at diagnosis of NDM indicates that this test is useful for assessing chronic hyperglycemia in NDM.

Fanconi syndrome and neonatal diabetes: phenotypic heterogeneity in patients with GLUT2 defects

Fanconi-Bickel syndrome, caused by mutations in SLC2A2 encoding the glucose transporter 2 (GLUT2), is characterized by generalized proximal renal tubular dysfunction manifesting in late infancy. We describe phenotypic heterogeneity of Fanconi-Bickel syndrome in three siblings, including early and atypical presentation with transient neonatal diabetes mellitus in one. The second-born of a non-consanguineous couple, evaluated for polyuria and growth retardation, had rickets, hepatomegaly and proximal tubular dysfunction from 4 to 6  months of age. A male sibling, who expired at 4 months, also had hepatomegaly and growth retardation. The third sibling had polyuria, glucosuria and mild proteinuria on day 3 of life. Hyperglycemia was detected 2 weeks later, which required therapy with insulin for 3 months. Mild metabolic acidosis was present at 2 weeks; hypercalciuria, phosphaturia and aminoaciduria were seen at 6 months. Sanger sequencing showed a homozygous missense mutation in SLC2A2 (exon 7, c.952G > A), causing glycine to arginine substitution; both parents were heterozygous carriers. Patients with SLC2A2 mutations may present either with isolated neonatal diabetes or with hepatomegaly and the renal Fanconi syndrome. Fanconi-Bickel syndrome shows phenotypic heterogeneity and may manifest early with subtle or atypical features, mandating a high index of suspicion.

The triggering pathway to insulin secretion: Functional similarities and differences between the human and the mouse β cells and their translational relevance

In β cells, stimulation by metabolic, hormonal, neuronal, and pharmacological factors is coupled to secretion of insulin through different intracellular signaling pathways. Our knowledge about the molecular machinery supporting these pathways and the patterns of signals it generates comes mostly from rodent models, especially the laboratory mouse. The increased availability of human islets for research during the last few decades has yielded new insights into the specifics in signaling pathways leading to insulin secretion in humans. In this review, we follow the most central triggering pathway to insulin secretion from its very beginning when glucose enters the β cell to the calcium oscillations it produces to trigger fusion of insulin containing granules with the plasma membrane. Along the way, we describe the crucial building blocks that contribute to the flow of information and focus on their functional role in mice and humans and on their translational implications.

Anti-diabetic drug binding site in a mammalian KATP channel revealed by Cryo-EM

Sulfonylureas are anti-diabetic medications that act by inhibiting pancreatic K_ATP channels composed of SUR1 and Kir6.2. The mechanism by which these drugs interact with and inhibit the channel has been extensively investigated, yet it remains unclear where the drug binding pocket resides. Here, we present a cryo-EM structure of a hamster SUR1/rat Kir6.2 channel bound to a high-affinity sulfonylurea drug glibenclamide and ATP at 3.63 Å resolution, which reveals unprecedented details of the ATP and glibenclamide binding sites. Importantly, the structure shows for the first time that glibenclamide is lodged in the transmembrane bundle of the SUR1-ABC core connected to the first nucleotide binding domain near the inner leaflet of the lipid bilayer. Mutation of residues predicted to interact with glibenclamide in our model led to reduced sensitivity to glibenclamide. Our structure provides novel mechanistic insights of how sulfonylureas and ATP interact with the K_ATP channel complex to inhibit channel activity.

Pancreatic Agenesis due to Compound Heterozygosity for a Novel Enhancer and Truncating Mutation in the PTF1A Gene

Neonatal diabetes, defined as the onset of diabetes within the first six months of life, is very rarely caused by pancreatic agenesis. Homozygous truncating mutations in the PTF1A gene, which encodes a transcriptional factor, have been reported in patients with pancreatic and cerebellar agenesis, whilst mutations located in a distal pancreatic-specific enhancer cause isolated pancreatic agenesis. We report an infant, born to healthy non-consanguineous parents, with neonatal diabetes due to pancreatic agenesis. Initial genetic investigation included sequencing of KCNJ11, ABCC8 and INS genes, but no mutations were found. Following this, 22 neonatal diabetes associated genes were analyzed by a next generation sequencing assay. We found compound heterozygous mutations in the PTF1A gene: A frameshift mutation in exon 1 (c.437_462 del, p.Ala146Glyfs*116) and a mutation affecting a highly conserved nucleotide within the distal pancreatic enhancer (g.23508442A>G). Both mutations were confirmed by Sanger sequencing. Isolated pancreatic agenesis resulting from compound heterozygosity for truncating and enhancer mutations in the PTF1A gene has not been previously reported. This report broadens the spectrum of mutations causing pancreatic agenesis.

Sulfonylurea treatment in an infant with transient neonatal diabetes mellitus caused by an adenosine triphosphate binding cassette subfamily C member 8 gene mutation

Neonatal diabetes mellitus (NDM) is an insulin-requiring monogenic form of diabetes that generally presents before six months of age. The following two types of NDM are known: transient NDM (TNDM) and permanent NDM (PNDM). Here we report on an infant with TNDM caused by a mutation (p.Gly832Cys) of the gene for the ATP binding cassette subfamily C member 8 (ABCC8). The patient exhibited hyperglycemia (600 mg/dL) at five weeks of age and insulin treatment was initiated. As genetic analysis identified a missense mutation within ABCC8, the insulin was replaced by glibenclamide at five months of age. Thereafter, the insulin was successfully withdrawn and his glycemic condition was well controlled at a dose of 0.0375 mg/kg/d. Since the patient’s blood glucose was under control and serum C-peptide levels were measurable, glibenclamide was stopped at 1 yr, 10 mo of age. The lack of DM relapsed to date confirms the TNDM diagnosis. In conclusion, when insulin is replaced with a sulfonylurea-class medication (SU) in NDM patients, serum C-peptide levels should be closely monitored and fine adjustment of SU dose is recommended.

Neonatal Diabetes: Case Report of a 9-Week-Old Presenting Diabetic Ketoacidosis Due to an Activating ABCC8 Gene Mutation

Context: Neonatal diabetes mellitus, a rare condition occurring in approximately 1 in 500 000 live births, is defined as insulin-requiring hyperglycemia presenting in the first months of life. Neonatal diabetes can be transient or permanent, with studies characterizing the condition as a monogenic disorder. Case Report: We describe a case of a 9-week-old infant with neonatal diabetes who presented in diabetic ketoacidosis due to a mutation affecting the ABCC8 gene that encodes the SUR1 subunit of the potassium ATP channel. Conclusion: This genetic diagnosis has therapeutic implications regarding the initiation of sulfonylurea administration as 85% of patients with neonatal diabetes due to ABCC8 gene mutations can be successfully treated with oral sulfonylurea treatment.

An infant with diabetes mellitus: Is it always T1DM?

Here we describe a 2^1/2month old infant with neonatal diabetes mellitus (NDM) who was initially misdiagnosed to have T1DM and initiated on insulin. He was found to have a novel heterozygous mutation Arg992Cys in ABCC 8 gene and successfully switched to oral anti-diabetic drug.

Epidemiology, clinical characteristics, and genetic etiology of neonatal diabetes in Japan

Neonatal diabetes mellitus (NDM) is a rare but potentially devastating metabolic disorder, with a reported incidence of one per 300 000-500 000 births generally, and hyperglycemia develops within the first 6 months of life. NDM is classified into two categories clinically. One is transient NDM (TNDM), in which insulin secretion is spontaneously recovered by several months of age, but sometimes recurs later, and the other is permanent NDM (PNDM), requiring lifelong medication. Recent molecular analysis of NDM identified at least 12 genetic abnormalities: chromosome 6q24, KCNJ11, ABCC8, INS, FOXP3, GCK, IPF1, PTF1A, EIF2AK3, GLUT2, HNF1β, and GLIS3. Of these, imprinting defects on chromosome 6q24 and the KCNJ11 mutation have been recognized as the major causes of TNDM and PNDM, respectively, in Caucasian subjects. Although the pathogenesis and epidemiology of NDM in Japan seem to be clinically distinct, they are still unclear. In this review, we summarize the epidemiology, clinical characteristics, and genetic etiology in Japanese patients with NDM compared with the data on Caucasian patients.

Monitoring p53 by MDM2 and MDMX is required for endocrine pancreas development and function in a spatio-temporal manner

Although p53 is not essential for normal embryonic development, it plays a pivotal role in many biological and pathological processes, including cell fate determination-dependent and independent events and diseases. The expression and activity of p53 largely depend on its two biological inhibitors, MDM2 and MDMX, which have been shown to form a complex in order to tightly control p53 to an undetectable level during early stages of embryonic development. However, more delicate studies using conditional gene-modification mouse models show that MDM2 and MDMX may function separately or synergistically on p53 regulation during later stages of embryonic development and adulthood in a cell and tissue-specific manner. Here, we report the role of the MDM2/MDMX-p53 pathway in pancreatic islet morphogenesis and functional maintenance, using mouse lines with specific deletion of MDM2 or MDMX in pancreatic endocrine progenitor cells. Interestingly, deletion of MDM2 results in defects of embryonic endocrine pancreas development, followed by neonatal hyperglycemia and lethality, by inducing pancreatic progenitor cell apoptosis and inhibiting cell proliferation. However, unlike MDM2-knockout animals, mice lacking MDMX in endocrine progenitor cells develop normally. But, surprisingly, the survival rate of adult MDMX-knockout mice drastically declines compared to control mice, as blockage of neonatal development of endocrine pancreas by inhibition of cell proliferation and subsequent islet dysfunction and hyperglycemia eventually lead to type 1 diabetes-like disease with advanced diabetic nephropathy. As expected, both MDM2 and MDMX deletion-caused pancreatic defects are completely rescued by loss of p53, verifying the crucial role of the MDM2 and/or MDMX in regulating p53 in a spatio-temporal manner during the development, functional maintenance, and related disease progress of endocrine pancreas. Also, our study suggests a possible mouse model of advanced diabetic nephropathy, which is complementary to other established diabetic models and perhaps useful for the development of anti-diabetes therapies.

Incidence, prevalence and genetic determinants of neonatal diabetes mellitus: a systematic review and meta-analysis protocol

BACKGROUND

In the absence of existing data, the present review intends to determine the incidence, prevalence and/or genetic determinants of neonatal diabetes mellitus (NDM), with expected contribution to disease characterization.

METHODS

We will include cross-sectional, cohort or case-control studies which have reported the incidence, prevalence and/or genetic determinants of NDM between January 01, 2000 and May 31, 2016, published in English or French languages and without any geographical limitation. PubMed and EMBASE will be extensively screened to identify potentially eligible studies, completed by manual search. Two authors will independently screen, select studies, extract data, and assess the risk of bias; disagreements will be resolved by consensus. Clinical heterogeneity will be investigated by examining the design and setting (including geographic region), procedure used for genetic testing, calculation of incidence or prevalence, and outcomes in each study. Studies found to be clinically homogeneous will be pooled together through a random effects meta-analysis. Statistical heterogeneity will be assessed using the chi-square test of homogeneity and quantified using the I 2 statistic. In case of substantial heterogeneity, subgroup analyses will be undertaken. Publication bias will be assessed with funnel plots, complemented with the use of Egger's test of bias.

DISCUSSION

This systematic review and meta-analysis is expected to draw a clear picture of phenotypic and genotypic presentations of NDM in order to better understand the condition and adequately address challenges in respect with its management.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016039765.

Age-Adjusted Glycated Albumin at Diagnosis is more Correlated with the Product of Age and Plasma Glucose than Plasma Glucose Alone in Patients with Neonatal Diabetes Mellitus

BACKGROUND

We previously showed that glycated albumin (GA) is a useful glycemic control indicator in patients with neonatal diabetes mellitus (NDM), and that age-adjusted GA (Aa-GA) can reflect more accurately glycemic control status. Here, we investigated whether the age at diagnosis influences Aa-GA at diagnosis of NDM.

METHODS

Eight patients with NDM whose GA was measured at diagnosis (age at diagnosis: 39 ± 18 days; GA: 31.3 ± 7.6%; Aa-GA: 47.1 ± 10.3%; plasma glucose: 525 ± 194 mg/dl) were included. Aa-GA was calculated as follows: Aa-GA = GA × 14.0/[1.77 × log-age (days) + 6.65]. Correlations of GA or Aa-GA at diagnosis with its logarithmically transformed age in days (log-age), plasma glucose, and their product were investigated.

RESULTS

GA at diagnosis was not significantly correlated with log-age or plasma glucose. On the other hand, Aa-GA at diagnosis was significantly positively correlated with plasma glucose (R = 0.75, P = 0.031) and was more strongly positively correlated with the product of plasma glucose and log-age (R = 0.82, P = 0.012) although it was not correlated with log-age.

CONCLUSION

Aa-GA at diagnosis is influenced by both age in days and plasma glucose. This finding is likely to show the aspect that age in days is almost equal to diabetes duration because glycemic control indicators including GA reflect the weighted mean of plasma glucose.

Gene Variants Associated with Transient Neonatal Diabetes Mellitus in the Very Low Birth Weight Infant

BACKGROUND

Transient and permanent neonatal diabetes mellitus (NDM), usually defined as diabetes diagnosed within the first 6 months of life, are rare conditions occurring in 1:90,000-260,000 live births. The origin of NDM is rarely related to type 1 diabetes, but rather to single gene defects.

METHODS

Genetic analysis was performed using targeted parallel sequencing including 323 diabetes genes. Data were filtered by a locally developed program.

RESULTS

A very low birth weight neonate born at 28 weeks postmenstrual age developed diabetes 13 days after birth. The patient was treated with continuous subcutaneous insulin infusion. After 1 month, insulin treatment could be stopped. At 18 months of age, the child was normoglycemic and developing normally. Genetic analysis revealed a novel variant (p.Pro190Leu) in HNF4A, which is located in the ligand binding domain of the transcription factor, and the p.Glu23Lys variant in KCNJ11, which is associated with type 2 diabetes.

CONCLUSION

Here, we describe a novel HNF4A variant associated with transient NDM in a premature infant. We hypothesize that the neonatal phenotype previously described in carriers of HNF4A mutations was modified by the additional variant in KCNJ11 and prematurity.

Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells

Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion.

PLAGL1: an important player in diverse pathological processes

The PLAGL1 gene encodes a homonymous zinc finger protein that promotes cell cycle arrest and apoptosis through multiple pathways. The protein has been implicated in metabolic, genetic, and neoplastic illnesses, but the molecular mechanisms by which the protein PLAGL1 participates in such diverse processes remains to be elucidated. In this review, we focus mainly on the molecular biology of PLAGL1 and the relevance of its abnormalities to several pathological processes.

Genome Editing of Lineage Determinants in Human Pluripotent Stem Cells Reveals Mechanisms of Pancreatic Development and Diabetes

Directed differentiation of human pluripotent stem cells (hPSCs) into somatic counterparts is a valuable tool for studying disease. However, examination of developmental mechanisms in hPSCs remains challenging given complex multi-factorial actions at different stages. Here, we used TALEN and CRISPR/Cas-mediated gene editing and hPSC-directed differentiation for a systematic analysis of the roles of eight pancreatic transcription factors (PDX1, RFX6, PTF1A, GLIS3, MNX1, NGN3, HES1, and ARX). Our analysis not only verified conserved gene requirements between mice and humans but also revealed a number of previously unsuspected developmental mechanisms with implications for type 2 diabetes. These include a role of RFX6 in regulating the number of pancreatic progenitors, a haploinsufficient requirement for PDX1 in pancreatic β cell differentiation, and a potentially divergent role of NGN3 in humans and mice. Our findings support use of systematic genome editing in hPSCs as a strategy for understanding mechanisms underlying congenital disorders.

Congenital Diabetes Mellitus

Introduction: Neonatal diabetes is a rare and surprising diagnosis, with many complications and difficult management by the medical team. Objectives: Management of the diabetes mellitus new-born in our maternity. Matherial and methods:Analysis of one of the rare cases of diagnosed neonatal diabetes. Conclusions:Given the rarity of such cases, this event can guide the medical care team consisting of obstetricians, neonatologist and diabetes doctor to effective collaboration by protocol management of new-born with diabetes mellitus suspicion.

STUDY OF KCNJ11 GENE MUTATIONS IN ASSOCIATION WITH MONOGENIC DIABETES OF INFANCY AND RESPONSE TO SULFONYLUREA TREATMENT IN A COHORT STUDY IN EGYPT

Introduction

KCNJ11 gene activating mutations play a major role in the development of neonatal diabetes mellitus (NDM). KCNJ 11 gene encodes the Kir 6.2 subunit of ATP- sensitive potassium channel which is a critical regulator of pancreatic beta-cell insulin secretion.

Aim

To study KCNJ11 gene mutations in infants with NDM and the effect of sulfonylurea treatment on the glycemic control in patients with KCNJ11 gene mutation.

Subjects and methods

Thirty infants with NDM were screened for KCNJ11 gene mutations by DNA sequencing, insulin therapy was replaced by sulfonylurea treatment in patients with mutations.

Results

R201C heterozygous mutation was found in one patient who was successfully shifted from insulin therapy to sulfonylurea treatment, while E23k, I337V, and S385C polymorphisms were detected in 14 patients.

Conclusion

Screening for KCNJ 11 gene mutations could lead to identification of patients with mutations who can be successfully shifted from insulin therapy to sulfonylurea treatment improving their quality of life.

Infantile onset diabetes mellitus in developing countries - India

Infantile onset diabetes mellitus (IODM) is an uncommon metabolic disorder in children. Infants with onset of diabetes mellitus (DM) at age less than one year are likely to have transient or permanent neonatal DM or rarely type 1 diabetes. Diabetes with onset below 6 mo is a heterogeneous disease caused by single gene mutations. Literature on IODM is scanty in India. Nearly 83% of IODM cases present with diabetic keto acidosis at the onset. Missed diagnosis was common in infants with diabetes (67%). Potassium channel mutation with sulphonylurea responsiveness is the common type in the non-syndromic IODM and Wolcott Rallison syndrome is the common type in syndromic diabetes. Developmental delay and seizures were the associated co-morbid states. Genetic diagnosis has made a phenomenal change in the management of IODM. Switching from subcutaneous insulin to oral hypoglycemic drugs is a major clinical breakthrough in the management of certain types of monogenic diabetes. Mortality in neonatal diabetes is 32.5% during follow-up from Indian studies. This article is a review of neonatal diabetes and available literature on IODM from India.

A seven weeks old baby with diabetic ketoacidosis: a case report

Diabetes mellitus is rare during infancy, however, it should be suspected in infants presenting with features consistent with sepsis and hyperglycemia. This is crucial in initiating the treatment of diabetes ketoacidosis which if delayed may result in significant morbidity and death.

Xenopus as a model system for studying pancreatic development and diabetes

Diabetes is a chronic disease caused by the loss or dysfunction of the insulin-producing β-cells in the pancreas. To date, much of our knowledge about β-cells in humans comes from studying rare monogenic forms of diabetes. Importantly, the majority of mutations so far associated to monogenic diabetes are in genes that exert a regulatory role in pancreatic development and/or β-cell function. Thus, the identification and study of novel mutations open an unprecedented window into human pancreatic development. In this review, we summarize major advances in the genetic dissection of different types of monogenic diabetes and the insights gained from a developmental perspective. We highlight future challenges to bridge the gap between the fast accumulation of genetic data through next-generation sequencing and the need of functional insights into disease mechanisms. Lastly, we discuss the relevance and advantages of studying candidate gene variants in vivo using the Xenopus as model system.

Transient neonatal diabetes due to a missense mutation (E227K) in the gene encoding the ATP-sensitive potassium channel (KCNJ11)

Neonatal diabetes is a monogenic form of diabetes. Herein, we report on a newborn presenting diabetic ketoacidosis at 17 days of life. A KCNJ11 mutation was identified. In such cases, insulin can be replaced by sulfonylurea with a successful metabolic control, as an example of how molecular diagnosis may influence the clinical management of the disorder.

Role of ZAC1 in transient neonatal diabetes mellitus and glucose metabolism

Transient neonatal diabetes mellitus 1 (TNDM1) is a rare genetic disorder representing with severe neonatal hyperglycaemia followed by remission within one and a half year and adolescent relapse with type 2 diabetes in half of the patients. Genetic defects in TNDM1 comprise uniparental isodisomy of chromosome 6, duplication of the minimal TNDM1 locus at 6q24, or relaxation of genomically imprinted ZAC1/HYMAI. Whereas the function of HYMAI, a non-coding mRNA, is still unidentified, biochemical and molecular studies show that zinc finger protein 1 regulating apoptosis and cell cycle arrest (ZAC1) behaves as a factor with versatile transcriptional functions dependent on binding to specific GC-rich DNA motives and interconnected regulation of recruited coactivator activities. Genome-wide expression profiling enabled the isolation of a number of Zac1 target genes known to regulate different aspects of β-cell function and peripheral insulin sensitivity. Among these, upregulation of Pparγ and Tcf4 impairs insulin-secretion and β-cell proliferation. Similarly, Zac1-mediated upregulation of Socs3 may attenuate β-cell proliferation and survival by inhibition of growth factor signalling. Additionally, Zac1 directly represses Pac1 and Rasgrf1 with roles in insulin secretion and β-cell proliferation. Collectively, concerted dysregulation of these target genes could contribute to the onset and course of TNDM1. Interestingly, Zac1 overexpression in β-cells spares the effects of stimulatory G-protein signaling on insulin secretion and raises the prospect for tailored treatments in relapsed TNDM1 patients. Overall, these results suggest that progress on the molecular and cellular foundations of monogenetic forms of diabetes can advance personalized therapy in addition to deepening the understanding of insulin and glucose metabolism in general.

Roles of imprinted genes in neural stem cells

Imprinted genes and neural stem cells (NSC) play an important role in the developing and mature brain. A central theme of imprinted gene function in NSCs is cell survival and G1 arrest to control cell division, cell-cycle exit, migration and differentiation. Moreover, genomic imprinting can be epigenetically switched off at some genes to ensure stem cell quiescence and differentiation. At the genome scale, imprinted genes are organized in dynamic networks formed by interchromosomal interactions and transcriptional coregulation of imprinted and nonimprinted genes. Such multilayered networks may synchronize NSC activity with the demand from the niche resembling their roles in adjusting fetal size.

Sulfonylurea in the treatment of neonatal diabetes mellitus children with heterogeneous genetic backgrounds

OBJECTIVE

The pathogenic base of neonatal diabetes mellitus (NDM) is highly heterogeneous. Sulfonylurea (SU) has been successfully applied in majority of NDM patients with KATP channel mutations; however, its rationality and effectiveness among patients with NDM stemmed from other genetic mutations have not been established. The objective of the present study was to investigate the effectiveness of SU therapy in NDM patients with heterogeneous genetic backgrounds.

METHODS

We identified 16 patients with NDM. These patients underwent SU titration and were followed after successful SU monotherapy. All patients were sequenced for all exons and adjacent intron-exon junctions of ABCC8, KCNJ11, and INS, and analyzed for 6q24 methylation defects. SU regimens were applied and glycemic status was evaluated in each patient.

RESULTS

Of the 16 patients, 15 (94%) reached glycemic goal (7-10 mmol/L) after SU monotherapy except one patient with the INS mutation. No significant side effects or organ damage were found in any of the 16 patients. Among these patients, five were found to harbor ABCC8 mutations, another five had mutations in KCNJ11, two had INS gene mutations, one with 6q24 hypomethylation, and three were absent for defects in genes tested.

CONCLUSION

Our study showed that SU monotherapy resulted in satisfactory glycemic control in most of the patients with NDM whose genetic defects are heterogeneous. The usage of SU may be considered as first-line therapy for patients with NDM in developing countries where effective genetic screening is not established.

Age-adjusted glycated albumin accurately reflects blood glucose in patients with neonatal diabetes mellitus: comparison with calculated glycated albumin determined by past blood glucose concentrations

Background

Glycated albumin is a useful glycaemic control indicator for neonatal diabetes mellitus. However, glycated albumin concentrations in infants are lower than those in adults and increase in an age-dependent manner. Based on our investigation of non-diabetic subjects, we proposed the possibility that the reference range for adults may be used regardless of age, provided that age-adjusted glycated albumin is employed. In the present study, we evaluate the usefulness of age-adjusted glycated albumin in neonatal diabetes mellitus patients.

Methods

Six neonatal diabetes mellitus patients (four patients with permanent neonatal diabetes mellitus and two patients with transient neonatal diabetes mellitus) were included. Measured glycated albumin or age-adjusted glycated albumin was compared to calculated glycated albumin, which was determined using calculation formulae we had reported based on past blood glucose over the 50 days before measurement of glycated albumin.

Results

Measured glycated albumin was significantly lower than calculated glycated albumin (20.5 ± 4.9% versus 28.2 ± 6.1%; p < 0.0001), whereas age-adjusted glycated albumin was equivalent to calculated glycated albumin, showing no significant difference (27.5 ± 6.8% versus 28.2 ± 6.1%). Measured glycated albumin concentrations in patients with transient neonatal diabetes mellitus in remission were lower than the reference range for adults, whereas age-adjusted glycated albumin concentrations were within the reference range for adults.

Conclusion

We demonstrated that age-adjusted glycated albumin concentrations were consistent with calculated glycated albumin. Age-adjusted glycated albumin is therefore a useful glycaemic control indicator for neonatal diabetes mellitus patients.

Imprinted Zac1 in neural stem cells

Neural stem cells (NSCs) and imprinted genes play an important role in brain development. On historical grounds, these two determinants have been largely studied independently of each other. Recent evidence suggests, however, that NSCs can reset select genomic imprints to prevent precocious depletion of the stem cell reservoir. Moreover, imprinted genes like the transcriptional regulator Zac1 can fine tune neuronal vs astroglial differentiation of NSCs. Zac1 binds in a sequence-specific manner to pro-neuronal and imprinted genes to confer transcriptional regulation and furthermore coregulates members of the p53-family in NSCs. At the genome scale, Zac1 is a central hub of an imprinted gene network comprising genes with an important role for NSC quiescence, proliferation and differentiation. Overall, transcriptional, epigenomic, and genomic mechanisms seem to coordinate the functional relationships of NSCs and imprinted genes from development to maturation, and possibly aging.

Neonatal hyperglycemia induces oxidative stress in the rat brain: the role of pentose phosphate pathway enzymes and NADPH oxidase

Recently, the consequences of diabetes on the central nervous system (CNS) have received great attention. However, the mechanisms by which hyperglycemia affects the central nervous system remain poorly understood. In addition, recent studies have shown that hyperglycemia induces oxidative damage in the adult rat brain. In this regard, no study has assessed oxidative stress as a possible mechanism that affects the brain normal function in neonatal hyperglycemic rats. Thus, the present study aimed to investigate whether neonatal hyperglycemia elicits oxidative stress in the brain of neonate rats subjected to a streptozotocin-induced neonatal hyperglycemia model (5-day-old rats). The activities of glucose-6-phosphate-dehydrogenase (G6PD), 6-phosphogluconate-dehydrogenase (6-PGD), NADPH oxidase (Nox), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), the production of superoxide anion, the thiobarbituric acid-reactive substances (TBA-RS), and the protein carbonyl content were measured. Neonatal hyperglycemic rats presented increased activities of G6PD, 6PGD, and Nox, which altogether may be responsible for the enhanced production of superoxide radical anion that was observed. The enhanced antioxidant enzyme activities (SOD, CAT, and GSHPx) that were observed in neonatal hyperglycemic rats, which may be caused by a rebound effect of oxidative stress, were not able to hinder the observed lipid peroxidation (TBA-RS) and protein damage in the brain. Consequently, these results suggest that oxidative stress could represent a mechanism that explains the harmful effects of neonatal hyperglycemia on the CNS.

Future challenges for pediatric diabetes management in developing countries: lessons from Africa

In this review, we describe the epidemiology of diabetes mellitus in children and adolescents in Africa, noting that there is a paucity of data with regard to the burden of disease, prevalence of undiagnosed diabetes, healthcare and acute and chronic complications. Furthermore, access to care remains an issue of great concern. Our view is that in the next 5 years, more research will be undertaken on the burden of the disease and on interventions to provide better access to care. While the majority of African countries still have a low incidence of diabetes in children, it is predicted that the incidence will increase and it is therefore essential that governments develop sustainable policies to deal with such increases.

Treatment of transient neonatal diabetes mellitus: insulin pump or insulin glargine? Our experience

Neonatal diabetes mellitus (NDM) results from impaired insulin secretion, occurring within the first 6 months of life. NDM is classified as transient NDM (TNDM) or permanent NDM. To date there are no universal guidelines regarding its management. Intravenous insulin infusion represents the first and most adequate therapeutic approach for sustained hyperglycemia, but this can provide only a short-term solution. Several factors should be taken into account in the choice of the long-term treatment. We describe our experience with two infants affected by TNDM. The first child was treated with continuous subcutaneous insulin infusion, whereas the second infant was treated with subcutaneous insulin glargine injections. Our experience shows that the two different therapeutic approaches, if properly managed, are equally effective.

Permanent neonatal diabetes misdiagnosed as type 1 diabetes in a 28-year-old female: a life-changing diagnosis

Many patients with monogenic diabetes are missed or misclassified. Herein, we report a 28-year-old Indian female who developed diabetes at the age of 3 months. An audit of our type 1 diabetes database led to her genetic testing. A KCNJ11 mutation was identified and she was successfully switched to sulphonylurea.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Neonatal diabetes in an infant of diabetic mother: same novel INS missense mutation in the mother and her offspring

Neonatal diabetes is defined as an uncontrolled hyperglycemic state occurring within the first 6 months of life. It is a rare disease with an incidence of 1 to 90,000-250,000. It is usually a disease of genetic origin in which insulin gene mutations play the main role in the disease process. A baby, born to a mother who had previously been diagnosed with type 1 diabetes mellitus at 14 months of age, had a high blood sugar level within the first few hours after birth and was subsequently diagnosed as having neonatal diabetes mellitus. Baby and mother were identified as having a novel heterozygous insulin missense mutation, p.C109R. Difficulties occurred in both follow-up and feeding of the baby. Without the addition of the mother's milk, an appropriate calorie milk formula and isophane insulin were used for the baby during follow-up. Multiple mechanisms are responsible in the pathogenesis of neonatal diabetes mellitus. Insulin gene mutations are one of the factors in the development of neonatal diabetes mellitus. If a resistant hyperglycemic state persists for a long time among babies, especially in those with intrauterine growth retardation whose mothers are diabetic, the baby concerned should be followed-up carefully for the development of neonatal diabetes mellitus.

Perk gene dosage regulates glucose homeostasis by modulating pancreatic β-cell functions

Background

Insulin synthesis and cell proliferation are under tight regulation in pancreatic β-cells to maintain glucose homeostasis. Dysfunction in either aspect leads to development of diabetes. PERK (EIF2AK3) loss of function mutations in humans and mice exhibit permanent neonatal diabetes that is characterized by insufficient β-cell mass and reduced proinsulin trafficking and insulin secretion. Unexpectedly, we found that Perk heterozygous mice displayed lower blood glucose levels.

Methodology

Longitudinal studies were conducted to assess serum glucose and insulin, intracellular insulin synthesis and storage, insulin secretion, and β-cell proliferation in Perk heterozygous mice. In addition, modulation of Perk dosage specifically in β-cells showed that the glucose homeostasis phenotype of Perk heterozygous mice is determined by reduced expression of PERK in the β-cells.

Principal Findings

We found that Perk heterozygous mice first exhibited enhanced insulin synthesis and secretion during neonatal and juvenile development followed by enhanced β-cell proliferation and a substantial increase in β-cell mass at the adult stage. These differences are not likely to entail the well-known function of PERK to regulate the ER stress response in cultured cells as several markers for ER stress were not differentially expressed in Perk heterozygous mice.

Conclusions

In addition to the essential functions of PERK in β-cells as revealed by severely diabetic phenotype in humans and mice completely deficient for PERK, reducing Perk gene expression by half showed that intermediate levels of PERK have a profound impact on β-cell functions and glucose homeostasis. These results suggest that an optimal level of PERK expression is necessary to balance several parameters of β-cell function and growth in order to achieve normoglycemia.

Glycemic control indicators in patients with neonatal diabetes mellitus

Neonatal diabetes mellitus (NDM) is a type of diabetes mellitus caused by genetic abnormality which develops in insulin dependent state within 6 mo after birth. HbA1c is widely used in clinical practice for diabetes mellitus as the gold standard glycemic control indicator; however, fetal hemoglobin (HbF) is the main hemoglobin in neonates and so HbA1c cannot be used as a glycemic control indicator in NDM. Glycated albumin (GA), another glycemic control indicator, is not affected by HbF. We reported that GA can be used as a glycemic control indicator in NDM. However, it was later found that because of increased metabolism of albumin, GA shows an apparently lower level in relation to plasma glucose in NDM; measures to solve this problem were needed. In this review, we outlined the most recent findings concerning glycemic control indicators in neonates or NDM.

Diabetes in the young - a global view and worldwide estimates of numbers of children with type 1 diabetes

This paper describes the methodology, results and limitations of the 2013 International Diabetes Federation (IDF) Atlas (6th edition) estimates of the worldwide numbers of prevalent cases of type 1 diabetes in children (<15 years). The majority of relevant information in the published literature is in the form of incidence rates derived from registers of newly diagnosed cases. Studies were graded on quality criteria and, if no information was available in the published literature, extrapolation was used to assign a country the rate from an adjacent country with similar characteristics. Prevalence rates were then derived from these incidence rates and applied to United Nations 2012 Revision population estimates for 2013 for each country to obtain estimates of the number of prevalent cases. Data availability was highest for the countries in Europe (76%) and lowest for the countries in sub-Saharan Africa (8%). The prevalence estimates indicate that there are almost 500,000 children aged under 15 years with type 1 diabetes worldwide, the largest numbers being in Europe (129,000) and North America (108,700). Countries with the highest estimated numbers of new cases annually were the United States (13,000), India (10,900) and Brazil (5000). Compared with the prevalence estimates made in previous editions of the IDF Diabetes Atlas, the numbers have increased in most of the IDF Regions, often reflecting the incidence rate increases that have been well-documented in many countries. Monogenic diabetes is increasingly being recognised among those with clinical features of type 1 or type 2 diabetes as genetic studies become available, but population-based data on incidence and prevalence show wide variation due to lack of standardisation in the studies. Similarly, studies on type 2 diabetes in childhood suggest increased incidence and prevalence in many countries, especially in Indigenous peoples and ethnic minorities, but detailed population-based studies remain limited.

New opportunities: harnessing induced pluripotency for discovery in diabetes and metabolism

The landmark discovery of induced pluripotent stem cells (iPSCs) by Shinya Yamanaka has transformed regenerative biology. Previously, insights into the pathogenesis of chronic human diseases have been hindered by the inaccessibility of patient samples. However, scientists are now able to convert patient fibroblasts into iPSCs and differentiate them into disease-relevant cell types. This ability opens new avenues for investigating disease pathogenesis and designing novel treatments. In this review, we highlight the uses of human iPSCs to uncover the underlying causes and pathological consequences of diabetes and metabolic syndromes, multifactorial diseases whose etiologies have been difficult to unravel using traditional methodologies.

Insulin secretion and Ca2+ dynamics in β-cells are regulated by PERK (EIF2AK3) in concert with calcineurin

Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) (EIF2AK3) is essential for normal development and function of the insulin-secreting β-cell. Although genetic ablation of PERK in β-cells results in permanent neonatal diabetes in humans and mice, the underlying mechanisms remain unclear. Here, we used a newly developed and highly specific inhibitor of PERK to determine the immediate effects of acute ablation of PERK activity. We found that inhibition of PERK in human and rodent β-cells causes a rapid inhibition of secretagogue-stimulated subcellular Ca(2+) signaling and insulin secretion. These dysfunctions stem from alterations in store-operated Ca(2+) entry and sarcoplasmic endoplasmic reticulum Ca(2+)-ATPase activity. We also found that PERK regulates calcineurin, and pharmacological inhibition of calcineurin results in similar defects on stimulus-secretion coupling. Our findings suggest that interplay between calcineurin and PERK regulates β-cell Ca(2+) signaling and insulin secretion, and that loss of this interaction may have profound implications in insulin secretion defects associated with diabetes.