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.

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.

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 (AUC_CP), the baseline CP (CP_Base) and the peak CP (CP_max). Threshold points of CP_Base, CP₉₀, CP_max and CP_AUC were determined from analysis of ROC curves.

RESULTS

GCK diabetes patients had significantly higher AUC_CP, CP_Base and CP_max 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.

SUN-602 Weight Loss After Glucagon-Like Peptide-1 Receptor Agonist Treatment in Childhood Obesity with Diabetes and Cirrhosis Associated with a Homozygous MC4R Mutation

Background

Mutations in the melanocortin-4 receptor (MC4R) represent the most common cause of monogenic obesity. Treatment options are limited but glucagon-like peptide-1 receptor agonists (GLP-1 RA) may be of use to induce weight loss.

Methods

Exome of the patient was captured using the Agilent SureSelect QXT Human All Exon V5 kit and sequenced on Illumina.

Clinical findings and results

We report obesity-associated diabetes and cirrhosis in a 13-year girl born from consanguineous parents of Afghan origin. Past medical history revealed mild mental retardation and excessive weight gain since infancy. Linear growth was normal. Her father was obese and no diabetes was found in the family. The girl was initially investigated for hoarseness and found to have pulmonary hypertension, later accepted to be secondary to cirrhosis and portal hypertension. Physical examination revealed obesity (BMI 34.9kg/m2) and acanthosis nigricans. Blood exams showed leucopenia and thrombocytopenia without anemia, compatible with portal hypertension. Chest CT revealed important dilatation of the pulmonary arteries, a nodular liver and splenomegaly. Liver biopsy confirmed cirrhosis. An extensive workup including whole exome sequencing identified a homozygous MC4R variant [NM_005912.2 (MC4R): c.63_64del, p.(Tyr21*)], classified as pathogenic according to the ACMG guidelines. Both parents were heterozygous for this variant. An endocrinological workup showed insulin resistance with a HOMA-IR index of 7.27 and diabetes with peak blood glucose of 11.5mmol/l. HbA1c was 5.1% (32mmol/mol). Thyroid tests, leptin, proinsulin levels (3.5pmol/l, n &lt;11.0pmol/l) were normal.

The mutation being homozygous with a predicted complete loss of function (https://www.mc4r.org.uk/), no treatment with a MC4R agonist was tried. At the age of 15 years (BMI 36.0kg/m2), the patient underwent liver transplantation because of progressive portal hypertension and to halt the progression of pulmonary hypertension. At the age of 16 years (BMI 33.2kg/m2, HbA1c 4.9% (30.0 mmol/mol), HOMA-IR 5.3) a treatment with GLP-1 RA (liraglutide) was started at a dosage of 0.6mg and progressively increased to 3mg, in an attempt to induce weight loss, avoid the accumulation of liver fat and to protect the graft. GLP-1 RA is supposed to exerts its effects on appetite independently of the MC4R pathway. 2 months after liraglutide introduction, no side effects, a weight loss of 4kg and a decrease of appetite were observed (BMI 31.6kg/m2, HbA1c 4.5% (26mmol/mol), HOMA-IR 3.14).

Conclusion

Obesity-associated MCR4 mutations, in homozygous state, may lead to diabetes, liver cirrhosis and porto-pulmonary hypertension. Treatment options are scarce, but GLP-1 RA seem to have a rapid, positive effect on weight and metabolic control. Would earlier treatment have prevented progression to end-stage-liver disease and need for liver transplantation?

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.

Exome sequencing identifies a de novo FOXA2 variant in a patient with syndromic diabetes

OBJECTIVE

When diabetes is associated with congenital malformations, without autoimmune antibodies, a genetic cause is suspected. Here, we aimed to identify a defective gene that led to diabetes.

RESEARCH DESIGN AND METHODS

We performed an exome analysis of an index case and his healthy parents.

RESULTS

The child presented with childhood-onset diabetes, congenital hypopituitarism, cardiac malformation, and anal atresia. A DNA analysis revealed a heterozygous de novo pathogenic variant in the developmental transcription factor, forkhead box A2 (FOXA2). The mutation resided in the DNA-binding domain, which is highly conserved among species. Tridimensional molecular dynamics simulation modeling predicted an altered interaction between the mutated protein and DNA.

CONCLUSIONS

A defect in the FOXA2 DNA-binding domain was associated with childhood-onset diabetes and multiple congenital anomalies, which reflected the pleiotropic nature of the gene. This report extends the recently described phenotype of neonatal hypoglycemia to later-onset diabetes. We suggest to include FOXA2 analysis for neonatal hypoglycemia and to implement a long-term follow-up, particularly for the risk of diabetes.

Combined Pancreatic Islet-Lung-Liver Transplantation in a Pediatric Patient with Cystic Fibrosis-Related Diabetes

BACKGROUND

Cystic fibrosis-related diabetes (CFRD) is the most frequent extrapulmonary complication of cystic fibrosis (CF).

METHODS

We report the first combined pancreatic islet-lung-liver transplantation in a 14-year-old adolescent. CFTR was analyzed by Sanger sequencing. Further genes were analyzed by high-throughput sequencing.

RESULTS

The patient was diagnosed with CF at the age of 14 months. Nine years later, after diagnosis of CFRD, the patient's BMI and lung function began to decline. Bilateral lung transplantation with simultaneous liver transplantation was performed at the age of 14.5 years. The first islet transplantation (IT) was carried out 10 days later. Six months later, C-peptide secretion after arginine stimulation showed peak values of 371 pmol/L (vs. 569 pmol/L before IT) and insulin doses had slightly increased (1.40 vs. 1.11 units/kg/day before IT). A second IT was performed at the age of 15 years, a third at 16 years. Two years after the first IT, arginine-stimulated C-peptide secretion increased to 2,956 pmol/L and insulin doses could be reduced to 0.82 units/kg/day. HbA1c decreased from 7.3% (57.4 mmol/mol) to 5.9% (41.0 mmol/mol).

CONCLUSION

IT following lung and liver transplantation, with injection of islets into a transplanted organ, is feasible. It improves C-peptide secretion, decreases insulin needs, and lowers HbA1c.

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.

An Intervention by a Patient-Designed Do-It-Yourself Mobile Device App Reduces HbA1c in Children and Adolescents with Type 1 Diabetes: A Randomized Double-Crossover Study

BACKGROUND

Prevention of type 1 diabetes mellitus (T1DM)-related complications is dependent on metabolic control. The recommended glycated hemoglobin (HbA1c) values <7.5% (58.5 mmol/mol) are met only by a minority of diabetic children and especially adolescents. The aim of this study was to evaluate the impact of an intervention comprising the use of Webdia, a patient-designed app for smartphones, on metabolic control of T1DM in children.

METHODS

Fifty-five patients with T1DM, 10-18 years of age, were included in this single-center, randomized double-crossover study. We tested an intervention consisting of using Webdia for 3 months with monthly feedback and adaptation of the treatment. Main outcome was modification of HbA1c. Secondary outcomes were the prevalence of hypoglycemia and quality of life (QoL).

RESULTS

Of the 55 included patients, 33 completed the study, 9 dropped out, and 13 were excluded due to insufficient use of the app. The app was well accepted by the users who completed the study (46.4% rated the program as good and 39.3% as excellent). The intervention led to a reduction of HbA1c by 0.33%, compared to the control group in which HbA1c rose by 0.21% (P = 0.048) in patients with HbA1c values >8.0% (63.9 mmol/mol) at inclusion, without increasing the prevalence of hypoglycemia (8.52 ± 9.45 hypoglycemic events during last 2 weeks of intervention vs. 7.62 ± 6.37 observation, P = 0.680). QoL scores were not modified.

CONCLUSIONS

The intervention resulted in a significant decrease in HbA1c, without increasing the prevalence of hypoglycemia in patients with initial HbA1c >8.0% (63.9 mmol/mol).

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.

Genetic Defects of the β-Cell That Cause Diabetes

Individuals with higher-than-normal blood sugar levels used to be diagnosed as having either type 1 or type 2 diabetes. We now know that a wide range of different factors can cause diabetes, including single gene defects, which account for at least 1% of all diabetes cases and up to 4% of cases in the pediatric population. However, misdiagnosis remains common due to the considerable clinical overlap between the different diabetes forms. Monogenic diabetes onset can occur shortly after birth, as observed in neonatal diabetes mellitus, or any time later in life. The present chapter outlines the genes currently known to be involved in monogenic diabetes. Some of these genes are involved in β-cell development, with mutations often leading to a decreased β-cell number, while others play important roles in β-cell function and maintenance. Monogenic forms of autoimmune diabetes and epigenetic causes will also be discussed. A genetic diagnosis may influence treatment choice and prognosis determination and may also lead to family counseling. Genetic screening using next-generation sequencing is becoming more practical as it becomes increasingly accessible and less expensive.

Insulin secretion response during oral glucose tolerance test is related to low cardiorespiratory fitness in obese adolescents

BACKGROUND

The obesity paradox refers to a category of subjects who may be less prone to develop co-morbidities, such as type 2 diabetes. Cardiorespiratory fitness (CRF) has been identified as one of the key factors. We aimed at exploring the difference in insulin metabolism between fit and unfit obese adolescents.

METHODS

We recruited 22 obese adolescents and assessed CRF during an incremental treadmill test. According to a cut-off at 80% of predicted maximal oxygen consumption (VO2max), subjects were separated into low or normal CRF. Body composition was determined by densitometry. Serum levels of insulin were measured sequentially during an oral glucose tolerance test and insulin secretion responses were calculated.

RESULTS

Compared to adolescents with normal CRF, the ones with low CRF had higher insulin resistance indices (p=0.023) and insulin secretion response (p=0.010), independently of the body mass index z-score.

CONCLUSIONS

Interventions in obese adolescents should focus on the maintenance or improvement of CRF to at least 80% of predicted VO2max. Indeed, this cut-off was significantly related to insulin secretion responses, independently of the adiposity level. A CRF above the proposed cut-off may prevent the development of insulin resistance.

Widespread intracranial calcifications in the follow-up of a patient with cartilage-hair hypoplasia--anauxetic dysplasia spectrum disorder: a coincidental finding?

BACKGROUND/PURPOSE

Intracranial calcifications have been identified in many neurological disorders. To our knowledge, however, such findings have not been described in cartilage-hair hypoplasia - anauxetic dysplasia spectrum disorders (CHH-AD), a group of conditions characterized by a wide spectrum of clinical manifestations.

METHODS/RESULTS

We report a 22-year old female patient, diagnosed with this disorder during her first year of life, and in whom bilateral intracranial calcifications (frontal lobes, basal ganglia, cerebellar dentate nuclei) were discovered by brain MRI at the age of 17 years.

CONCLUSION

The etiology of this finding remains unclear. Some causes of such deposits can be of a reversible nature, thus prompting early recognition although their consequences on clinical outcome remain mostly unknown.

[Transition in diabetology]

For patients with type I diabetes, transition from pediatric to adult care is a challenge due to complex treatment requirements and the physical, psychological and social changes of adolescence. Members of the care team must recognize that while these emerging adults need to develop self-management skills, this may conflict at times with the developmentally appropriate desire for increasing autonomy. The role of nursing in coordinating a successful transition is critical for maintaining continuity of patient-centered care that responds to the specific needs of these young adults.

Many faces of monogenic diabetes

Monogenic diabetes represents a heterogeneous group of disorders resulting from defects in single genes. Defects are categorized primarily into two groups: disruption of β-cell function or a reduction in the number of β-cells. A complex network of transcription factors control pancreas formation, and a dysfunction of regulators high in the hierarchy leads to pancreatic agenesis. Dysfunction among factors further downstream might cause organ hypoplasia, absence of islets of Langerhans or a reduction in the number of β-cells. Many transcription factors have pleiotropic effects, explaining the association of diabetes with other congenital malformations, including cerebellar agenesis and pituitary agenesis. Monogenic diabetes variants are classified conventionally according to age of onset, with neonatal diabetes occurring before the age of 6 months and maturity onset diabetes of the young (MODY) manifesting before the age of 25 years. Recently, certain familial genetic defects were shown to manifest as neonatal diabetes, MODY or even adult onset diabetes. Patients with neonatal diabetes require a thorough genetic work-up in any case, and because extensive phenotypic overlap exists between monogenic, type 2, and type 1 diabetes, genetic analysis will also help improve diagnosis in these cases. Next generation sequencing will facilitate rapid screening, leading to the discovery of digenic and oligogenic diabetes variants, and helping to improve our understanding of the genetics underlying other types of diabetes. An accurate diagnosis remains important, because it might lead to a change in the treatment of affected subjects and influence long-term complications.

Inflammatory and prothrombotic states in obese children of European descent

Adipose tissue may release mediators that induce a chronic inflammatory state and alterations in coagulation, which contribute to insulin resistance, atherosclerosis, and thrombosis. We investigated whether inflammatory and/or prothrombotic states exist in obese children and assessed their interrelationship. Sixty-one subjects were recruited, aged between 6 and 16 years, to participate in a cross-sectional study at Children's University Hospital of Geneva. Selected pro/anti-inflammatory cytokines/chemokines and hemostasis parameters were measured in obese children and lean controls. Cardiovascular risk factors in the family were indexed. Fasting glucose level, insulin, prothrombin time (PT), fibrinogen, activated partial thromboplastin time (aPTT), D-dimer, endogenous thrombin potential (ETP), C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-10 (IL-10), interferon-γ-inducible-protein (IP-10), monocyte chemoattractant protein 1 (MCP-1), and interleukin-1 receptor antagonist (IL-1Ra) were measured. We estimated insulin resistance by homeostatic model assessment (HOMA). Anti- (IL-1Ra) and proinflammatory cytokines (MCP-1, IL-6) were significantly increased in obese children in comparison to the control group, even before puberty. Hemostasis was also altered in obese children with a significantly increased fibrinogen level, increased D-dimer, a shortened PT, as well as an increased ETP. No correlation was found between cytokine levels and hemostasis parameters, except for IL-6 and fibrinogen. Obese children present with inflammatory and prothrombotic states as early as 6 years of age and these states are similar in prepubertal and pubertal obese children. The cytokines IL-1Ra and MCP-1 were most significantly increased in obese children. Further investigation is necessary to determine if these cytokines, together with ETP, can reliably predict the development of diabetes and atherosclerosis.

Encephalitis associated with glutamic acid decarboxylase autoantibodies in a child: a treatable condition?

OBJECTIVE

To increase the recognition of glutamic acid decarboxylase autoantibodies-related encephalitis in childhood.

DESIGN

Case report and review of the literature.

PATIENT

A 6-year-old girl who had developed refractory seizures, developmental regression, and type 1 diabetes mellitus at age 25 months.

INTERVENTIONS

Blood analysis, electroencephalogram, cerebral magnetic resonance imaging, positron emission tomography scan, lumbar puncture, and measurement of glutamic acid decarboxylase activity were performed. Treatment with repeated plasmapheresis and rituximab, with concomitant antiepileptic drugs, was administered.

RESULTS

Highly elevated titers of glutamic acid decarboxylase autoantibodies were found in the serum, as well as in the cerebrospinal fluid. Major clinical improvement in parallel with a decrease in the levels of serum and cerebrospinal fluid antibodies was observed with treatment.

CONCLUSIONS

Encephalitis associated with glutamic acid decarboxylase autoantibodies is a severe epileptic disorder that occurs in young children as well as adults. It may be partially reversible with aggressive immunomodulatory treatment, including plasmapheresis and rituximab. Studies are warranted to determine whether early treatment leads to complete remission.

A homozygous missense mutation in SCNN1A is responsible for a transient neonatal form of pseudohypoaldosteronism type 1

Pseudohypoaldosteronism type 1 (PHA1) is a monogenic disorder of mineralocorticoid resistance characterized by salt wasting, hyperkalemia, high aldosterone levels, and failure to thrive. An autosomal recessive form (AR-PHA1) is caused by mutations in the epithelial sodium channel ENaC with usually severe and persisting multiorgan symptoms. The autosomal dominant form of PHA1 (AD-PHA1) is due to mutations in the mineralocorticoid receptor causing milder and transient symptoms restricted to the kidney. We identified a homozygous missense mutation in the SCNN1A gene (c.727T>C/p.Ser(243)Pro), encoding α-subunit of ENaC (α-ENaC) in a prematurely born boy with a severe salt-losing syndrome. The patient improved rapidly under treatment, and dietary salt supplementation could be stopped after 6 mo. Interestingly, the patient's sibling born at term and harboring the same homozygous Ser(243)Pro mutation showed no symptom of salt-losing nephropathy. In vitro expression of the αSer(243)Pro ENaC mutant revealed a slight but significant decrease in ENaC activity that is exacerbated in the presence of high Na(+) load. Our study provides the first evidence that ENaC activity is critical for the maintenance of salt balance in the immature kidney of preterm babies. Together with previous studies, it shows that, when the kidney is fully mature, the severity of the symptoms of AR-PHA1 is related to the degree of the ENaC loss of function. Finally, this study identifies a novel functional domain in the extracellular loop of ENaC.

Modeling intrauterine growth retardation in rodents: Impact on pancreas development and glucose homeostasis

Fetal adverse environment, such as insufficient maternal nutrition, placental insufficiency and stress, alters organ development and leads to poor fetal growth, also called intrauterine growth retardation (IUGR). IUGR is associated with an increased risk of perinatal mortality and morbidity as well as late-onset metabolic diseases, such as obesity, diabetes and hypertension in adulthood. In the rodent model, IUGR can be induced by fetal caloric restriction, fetal protein restriction, by exposure to high levels of glucocorticoids or by restricted placental blood supply. Such experimental IUGR models show a decreased beta cell mass and lower pancreatic insulin content. Recent research has provided an insight into the mechanisms responsible for the loss of beta cells. Here we review models that give further details about the molecular determinants of fetal and postnatal pancreatic islet development that are required to understand the consequences of fetal insults.

[The diabetic child and the specifics of insulin therapy]

The incidence of diabetes type I has increased considerably in young children with an annual increase in Switzerland of 23,8% over the last ten years. The development of rapid acting and long acting analogues allowed a significant progress in treatment. Multiple daily insulin injections together with carbohydrate counting as well as continuous subcutaneous insulin infusion (CSII) improved the quality of life and led to an increased daily flexibility. The incidence of severe hypoglycaemic events has decreased at the same time metabolic control improved. The development of interstitial glucose measurement (online) coupled to the insulin pump represents a step further towards the artificial pancreas. The new therapeutic strategies of immunomodulation will hopefully lead to secondary and tertiary prevention of diabetes.

[Epigenetic origin of diabetes and growth disorders]

The understanding of genomic imprinting has made us realize that maternal and paternal contributions to the embryo are different. Disturbances during the imprinting process may lead to different pathologies due to an imbalance of gene expression either maternally or paternally derived. Known epigenetic diseases such as neonatal diabetes, growth retardation or overgrowth syndromes as well as cancer are better understood. It has become clear that environmental factors can be at the origin of such epigenetic changes. Careful analysis and diagnosis of epigenetic diseases are important for patient treatment and outcome.

Severe congenital hyperinsulinism caused by a mutation in the Kir6.2 subunit of the adenosine triphosphate-sensitive potassium channel impairing trafficking and function

CONTEXT

The ATP-sensitive potassium (K(ATP)) channel, assembled from the inwardly rectifying potassium channel Kir6.2 and the sulfonylurea receptor 1, regulates insulin secretion in beta-cells. A loss of function of K(ATP) channels causes depolarization of beta-cells and congenital hyperinsulinism (CHI), a disease presenting with severe hypoglycemia in the newborn period.

OBJECTIVE

Our objective was identification of a novel mutation in Kir6.2 in a patient with CHI and molecular and cell-biological analysis of the impact of this mutation.

DESIGN AND SETTING

We combined immunohistochemistry, advanced life fluorescence imaging, and electrophysiology in HEK293T cells transiently transfected with mutant Kir6.2.

PATIENT AND INTERVENTION

The patient presented with macrosomia at birth and severe hyperinsulinemic hypoglycemia. Despite medical treatment, the newborn continued to suffer from severe hypoglycemic episodes, and at 4 months of age subtotal pancreatectomy was performed.

MAIN OUTCOME MEASURE

We assessed patch-clamp recordings and confocal microscopy in HEK293T cells.

RESULTS

We have identified a homozygous missense mutation, H259R, in the Kir6.2 subunit of a patient with severe CHI. Coexpression of Kir6.2(H259R) with sulfonylurea receptor 1 in HEK293T cells completely abolished K(ATP) currents in electrophysiological recordings. Double immunofluorescence staining revealed that mutant Kir6.2 was partly retained in the endoplasmic reticulum (ER) causing decreased surface expression as observed with total internal reflection fluorescence. Mutation of an ER-retention signal partially rescued the trafficking defect without restoring whole-cell currents.

CONCLUSION

The H259R mutation of the Kir6.2 subunit results in a channel that is partially retained in the ER and nonfunctional upon arrival at the plasma membrane.

Agenesis of human pancreas due to decreased half-life of insulin promoter factor 1

Neonatal diabetes mellitus can be transient or permanent. The severe form of permanent neonatal diabetes mellitus can be associated with pancreas agenesis. Normal pancreas development is controlled by a cascade of transcription factors, where insulin promoter factor 1 (IPF1) plays a crucial role. Here, we describe two novel mutations in the IPF1 gene leading to pancreas agenesis. Direct sequence analysis of exons 1 and 2 of the IPF1 gene revealed two point mutations within the homeobox in exon 2. Genetic analysis of the parents showed that each mutation was inherited from one parent. Mutations localized in helices 1 and 2, respectively, of the homeodomain, decreased the protein half-life significantly, leading to intracellular IPF1 levels of 36% and 27% of wild-type levels. Both mutant forms of IPF1 were normally translocated to the nucleus, and their DNA binding activity on different known target promoters was similar to that of the wild-type protein. However, transcriptional activity of both mutant IPF1 proteins, alone or in combination with HNF3 beta/Foxa2, Pbx1, or the heterodimer E47-beta 2 was reduced, findings accounted for by decreased IPF1 steady state levels and not by impaired protein-protein interactions. We conclude that the IPF1 level is critical for human pancreas formation.

Hepatic nuclear factor-3 (HNF-3 or Foxa2) regulates glucagon gene transcription by binding to the G1 and G2 promoter elements

Glucagon gene expression in the endocrine pancreas is controlled by three islet-specific elements (G3, G2, and G4) and the alpha-cell-specific element G1. Two proteins interacting with G1 have previously been identified as Pax6 and Cdx2/3. We identify here the third yet uncharacterized complex on G1 as hepatocyte nuclear factor 3 (HNF-3)beta, a member of the HNF-3/forkhead transcription family, which plays an important role in the development of endoderm-related organs. HNF-3 has been previously demonstrated to interact with the G2 element and to be crucial for glucagon gene expression; we thus define a second binding site for this transcription on the glucagon gene promoter. We demonstrate that both HNF-3alpha and -beta produced in heterologous cells can interact with similar affinities to either the G1 or G2 element. Pax6, which binds to an overlapping site on G1, exhibited a greater affinity as compared with HNF-3alpha or -beta. We show that both HNF-3beta and -alpha can transactivate glucagon gene transcription through the G2 and G1 elements. However, HNF-3 via its transactivating domains specifically impaired Pax6-mediated transactivation of the glucagon promoter but had no effect on transactivation by Cdx2/3. We suggest that HNF-3 may play a dual role on glucagon gene transcription by 1) inhibiting the transactivation potential of Pax6 on the G1 and G3 elements and 2) direct activation through G1 and G2.

Programming of the pancreas

The pancreas, as most of the digestive tract, derives from the endoderm. Differentiation of these early gut endoderm cells into the endocrine cells forming the pancreatic islets of Langerhans depends on a cascade of gene activation events. These are controlled by different classes of transcription factors including the homeodomain, the basic helix-loop-helix (bHLH) and the winged helix proteins. Recently, considerable progress has been made delineating this cascade. The present review focuses on the role of the different transcription factors during pancreas development, with a particular emphasis on the newly identified bHLH transcription factor neurogenin3.

Expression of neurogenin3 reveals an islet cell precursor population in the pancreas

Differentiation of early gut endoderm cells into the endocrine cells forming the pancreatic islets of Langerhans depends on a cascade of gene activation events controlled by transcription factors including the basic helix-loop-helix (bHLH) proteins. To delineate this cascade, we began by establishing the position of neurogenin3, a bHLH factor found in the pancreas during fetal development. We detect neurogenin3 immunoreactivity transiently in scattered ductal cells in the fetal mouse pancreas, peaking at embryonic day 15.5. Although not detected in cells expressing islet hormones or the islet transcription factors Isl1, Brn4, Pax6 or PDX1, neurogenin3 is detected along with early islet differentiation factors Nkx6.1 and Nkx2.2, establishing that it is expressed in immature cells in the islet lineage. Analysis of transcription factor-deficient mice demonstrates that neurogenin3 expression is not dependent on neuroD1/BETA2, Mash1, Nkx2.2, Nkx6.1, or Pax6. Furthermore, early expression of neurogenin3 under control of the Pdx1 promoter is alone sufficient to drive early and ectopic differentiation of islet cells, a capability shared by the pancreatic bHLH factor, neuroD1/BETA2, but not by the muscle bHLH factor, MyoD. However, the islet cells produced in these transgenic experiments are overwhelmingly (alpha) cells, suggesting that factors other than the bHLH factors are required to deviate from a default * cell fate. These data support a model in which neurogenin3 acts upstream of other islet differentiation factors, initiating the differentiation of endocrine cells, but switching off prior to final differentiation. The ability to uniquely identify islet cell precursors by neurogenin3 expression allows us to determine the position of other islet transcription factors in the differentiation cascade and to propose a map for the islet cell differentiation pathway.

Normal female infants born of mothers with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Women with congenital adrenal hyperplasia due to 21-hydroxylase deficiency, especially those patients with the salt-losing form, have decreased fertility rates. Pregnancy experience in this population is limited. We report the pregnancy outcomes and serial measurements of maternal serum steroid levels in four women with classic 21-hydroxylase deficiency, three of whom were female pseudohermaphrodites with the salt-losing form. These glucocorticoid-treated women gave birth to four healthy female newborns with normal female external genitalia, none of whom were affected with 21-hydroxylase deficiency. In three women, circulating androgen levels increased during gestation, but remained within the normal range for pregnancy during glucocorticoid therapy. In the fourth patient, androgen levels were strikingly elevated during gestation despite increasing the dose of oral prednisone from 5 to 15 mg/day (two divided doses). Notwithstanding the high maternal serum concentration of androgens, however, placental aromatase activity was sufficient to prevent masculinization of the external genitalia of the female fetus and quite likely the fetal brain, consistent with the idea that placental aromatization of androgens to estrogens is the principal mechanism that protects the female fetus from the masculinizing effects of maternal hyperandrogenism. These four patients highlight key issues in the management of pregnancy in women with 21-hydroxylase deficiency, particularly the use of endocrine monitoring to assess adrenal androgen suppression in the mother, especially when the fetus is female. Recommendations for the management of pregnancy and delivery in these patients are discussed.

Neonatal hyperinsulinism

Hyperinsulinism is the most frequent cause of severe, persistent hypoglycemia in neonates and young infants. Timely diagnosis and aggressive treatment are necessary to prevent long-term neurologic sequelae. This article explores the latest advances in the understanding of the pathophysiology of this disorder at the molecular and cellular level. The clinical features, hallmarks for diagnosis, and various treatment options are discussed.