From diarrhea to obesity in prohormone convertase 1/3 deficiency: age-dependent clinical, pathologic, and enteroendocrine characteristics

GOALS The aim of this report is to delineate the clinical, pathologic, and enteroendocrine (EE) features of prohormone convertase 1/3 (PC1/3) deficiency in children. BACKGROUND Prohormone convertases play a pivotal role in the activation of biologically inactive hormones. Congenital defects in the EE axis, such as PC1/3 deficiency, have been rarely reported and their pathophysiological mechanisms are largely unknown. STUDY EE function and pathology was evaluated in 4 males (1, 2, 7, and 10 y old) from 2 families with PC1/3 deficiency at a university children's hospital. Clinical course, pathology analysis including immunohistochemistry for PC1/3, PC2, and glucagon-like peptide 1 (GLP-1) and electron microscopy, as well as EE function tests (GLP-1, GLP-2, oral glucose tolerance test) were performed. RESULTS All (n=4) suffered from congenital severe diarrhea associated with malabsorption. The diarrhea improved during the first year of life and hyperphagia with excessive weight gain (BMI>97th percentile) became the predominant phenotype at an older age. Analysis of the enteroendocrine axis revealed high proinsulin levels (57 to 1116 pmol/L) in all patients, low serum GLP-2 levels, and impaired insulin and GLP-1 secretion after an oral glucose tolerance test at a young age, with improvement in 1 older child tested. Electron microscopy showed normal ultrastructure of enterocytes and EE cells. Immunohistochemistry revealed normal expression of chromogranin A, a marker of EE cells but markedly reduced immunostaining for PC1/3 and PC2 in all patients. CONCLUSIONS PC1/3 deficiency is associated with an age dependent, variable clinical phenotype caused by severe abnormalities in intestinal and EE functions. Serum level of proinsulin can be used as an effective screening tool.

The diabetic child in the emergency room

The WHO announced diabetes mellitus as one of the main threats to human health in the 21st century. In children and adolescents the prevalence of both the autoimmune type 1 and the obesity-related type 2 diabetes is increasing. Common to all types of diabetes is an absolute or relative lack of insulin to keep glucose homeostasis under control. Thus children and adolescents with newly diagnosed diabetes present with hyperglycemia which is often accompanied by ketoacidosis bearing the risk of cerebral edema. Children and adolescents with known diabetes treated with insulin or orale antidiabetic agents may also suffer from hyperglycemia or even ketoacidosis during times of non-compliance with diet and drugs or during concomitant illnesses. Hyperglycemia with ketoacidosis is an emergency situation for which patients need to be admitted to the next hospital for administration of insulin, fluids and potassium. In contrast, insulin treatment in diabetic patients may also lead to a hypoglycemia, the sudden drop in blood glucose, at any moment. Thus recognition and correction of mild hypoglycemia should be familiar to every diabetic child and their caretaker. Severe hypoglycemia with or without seizures may bring the diabetic child in a sudden emergency situation for which the administration of glucagon intramuscularly or glucose intravenously is mandatory. After every severe hypoglycemia the insulin and diet regimen of the diabetic child or adolescent must be reviewed with the diabetes specialist. For unexplained hypoglycemia or major treatment adjustments the diabetic child or adolescent may need to be readmitted to the diabetic ward of a hospital to avoid repeat, potentially life-threatening hypoglycemia.

Asthma and obesity in children: current evidence and potential systems biology approaches.

Both obesity and asthma are highly prevalent, complex diseases modified by multiple factors. Genetic, developmental, lung mechanical, immunological and behavioural factors have all been suggested as playing a causal role between the two entities; however, their complex mechanistic interactions are still poorly understood and evidence of causality in children remains scant. Equally lacking is evidence of effective treatment strategies, despite the fact that imbalances at vulnerable phases in childhood can impact long-term health. This review is targeted at both clinicians frequently faced with the dilemma of how to investigate and treat the obese asthmatic child and researchers interested in the topic. Highlighting the breadth of the spectrum of factors involved, this review collates evidence regarding the investigation and treatment of asthma in obese children, particularly in comparison with current approaches in 'difficult-to-treat' childhood asthma. Finally, the authors propose hypotheses for future research from a systems-based perspective.