Refinement of the critical genomic region for congenital hyperinsulinism in the Chromosome 9p deletion syndrome

Version 2; peer review: 3 approved. Available from F1000 Research via the DOI in this recordBackground: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome. A range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown. Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: In 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated. Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.Wellcome TrustRoyal Societ

Systematic genetic testing for recessively inherited monogenic diabetes: a cross-sectional study in paediatric diabetes clinics

Data availability: The datasets supporting the current study have not been deposited in a public repository due to institutional ethics restrictions but are available from the corresponding author on request.This is the final version. Available from Springer via the DOI in this record. AIMS/HYPOTHESIS: Current clinical guidelines for childhood-onset monogenic diabetes outside infancy are mainly focused on identifying and testing for dominantly inherited, predominantly MODY genes. There are no systematic studies of the recessively inherited causes of monogenic diabetes that are likely to be more common in populations with high rates of consanguinity. We aimed to determine the contribution of recessive causes of monogenic diabetes in paediatric diabetes clinics and to identify clinical criteria by which to select individuals for recessive monogenic diabetes testing. METHODS: We conducted a cross-sectional study of 1093 children from seven paediatric diabetes clinics across Turkey (a population with high rates of consanguinity). We undertook genetic testing of 50 known dominant and recessive causes of monogenic diabetes for 236 children at low risk of type 1 diabetes. As a comparison, we used monogenic diabetes cases from UK paediatric diabetes clinics (a population with low rates of consanguinity). RESULTS: Thirty-four children in the Turkish cohort had monogenic diabetes, equating to a minimal prevalence of 3.1%, similar to that in the UK cohort (p = 0.40). Forty-one per cent (14/34) had autosomal recessive causes in contrast to 1.6% (2/122) in the UK monogenic diabetes cohort (p 10%) assisted the identification of the dominant (all p ≤ 0.0003) but not recessive cases (all p ≥ 0.2) in Turkey. The presence of certain non-autoimmune extra-pancreatic features greatly assisted the identification of recessive (p < 0.0001, OR 66.9) but not dominant cases. CONCLUSIONS/INTERPRETATION: Recessively inherited mutations are a common cause of monogenic diabetes in populations with high rates of consanguinity. Present MODY-focused genetic testing strategies do not identify affected individuals. To detect all cases of monogenic paediatric diabetes, it is crucial that recessive genes are included in genetic panels and that children are selected for testing if they have certain non-autoimmune extra-pancreatic features in addition to current criteria.Wellcome TrustRoyal SocietyNational Institute for Health Researc

Concentration in Normal-Weight and Obese Children

Objective: In studies on the relationship between amino-terminal propeptide of C-type natriuretic peptide (NT-proCNP) concentration and height velocity in children, CNP has been implicated as an emerging new growth marker during childhood. It has been reported that besides its well-studied role in growth, plasma CNP levels are reduced in overweight and/or obese adolescents, suggesting CNP as a potential biomarker in childhood obesity. The primary goal of this study was to test this hypothesis in a Turkish population.Methods: Consent was taken from 317 children [ages 0-18 (158 girls, 159 boys)] and their parents. All subjects were physically examined; anthropometric measurements were obtained. Body mass index was calculated. During routine blood work, 1 mL extra blood was taken. Plasma NT-proCNP concentration was measured by enzyme-linked immunosorbent assay.Results: Results confirmed the previously described relationship between plasma NT-proCNP concentration and growth velocity. Plasma NT-proCNP concentration showed a negative correlation with age, weight, and height in children. Gender was not a factor that alters the age-dependent plasma NT-proCNP concentration until puberty.Conclusion: Unlike previous reports, plasma NT-proCNP concentration of overweight/obese children was not significantly lower than that of children with normal weight in age groups analyzed in a Turkish population. Thus, it is too early to conclude that CNP is a potential biomarker in childhood obesity. Further studies are necessary to address this question

The etiology and clinical features of non-CAH gonadotropin-independent precocious puberty: A multicenter study

PubMed ID: 26964727Aim: The causes of gonadotropin-independent precocious puberty are diverse, and often have overlapping clinical and biochemical features. With the exception of congenital adrenal hyperplasia (CAH), disorders that cause gonadotropin-independent precocious puberty (GIPP) are uncommon. The literature is devoid of any large-scale studies on the etiologic distribution of GIPP. The aim of this study was to determine the frequency of each etiology in a cohort of patients with GIPP (excluding those with CAH), and to evaluate the clinical and laboratory features of these patients. Materials and Methods: This multicenter, nationwide web-based study collected data on patients who presented with non-CAH GIPP in Turkey. Results: Data were collected for 129 patients (102 girls and 27 boys) from 29 centers. Based on the data collected, the estimated prevalence of non-CAH GIPP in the studied population was 14 in 1 000 000 children. Functional ovarian cyst was the most common etiology, accounting for 37% of all cases, followed by McCune-Albright syndrome (MAS) (26%). Among the patients with MAS, 11.7% had fibrous dysplasia, 32.3% had café-au-lait spots, and 52.9% had both. Human chorionic gonadotrophin-secreting tumors included choriocarcinoma of the liver, hepatoblastoma, and germ cell tumors of the sellar-suprasellar region and mediastinum. Patients with adrenocortical tumors presented at an earlier age than those with other etiologies. Ovarian tumors included mature cystic teratoma, dysgerminoma, juvenile granulosa tumor, and steroid cell tumor. Despite overlapping features, it was possible to identify some unique clinical and laboratory features associated with each etiology. Conclusion: This largest cohort of patients with non-CAH GIPP to date yielded an estimation of the frequency of non-CAH GIPP in the general pediatric population and showed that girls were affected at a rate 4-fold greater than that of boys owing to functional ovarian cysts and MAS, which were the two most common etiologies. The data collected also provided some unique characteristics associated with each etiology. Copyright © 2016 by the Endocrine Society

Response to growth hormone with respect to pubertal status on increased dose in idiopathic growth hormone deficiency: An analysis of Turkish children in the KIGS database (Pfizer International Growth Study)

Aim: To compare the growth response to growth hormone (GH) treatment in patients with idiopathic GH deficiency (IGHD) who were prepubertal with the response of those who were pubertal at the onset of GH therapy on an increased GH dose