Efficacy and safety of a 4-year combination therapy of growth hormone and gonadotropin-releasing hormone analogue in pubertal girls with short predicted adult height.

Objectives: To improve adult height in pubertal girls with a poor height prediction, treatment with growth hormone (GH) can be used in combination with a gonadotropin releasing hormone agonist (GnRHa), to delay closure of the growth plates. However, there are few studies to support this practice, and they show conflicting results. The objective of this trial is to assess the safety and efficacy of this combination treatment in early pubertal girls with a short predicted height, in comparison with matched controls. Design patients and methods: We designed an open-label, multicenter, interventional case-control study. Early pubertal girls with predicted adult height (PAH) below -2.5 SDS, were recruited in tertiary care centers in Belgium. They were treated for four years with GH and GnRHa. The girls were followed until adult height (AH) was reached. AH vs PAH, AH vs Height at start, and AH vs Target Height (TH) were evaluated, as well as safety parameters. Control data were assembled from historical patient files or from patients who preferred not to participate in the study. Results: Sixteen girls with mean age ( ± SD) at start of 11.0 years (± 1.3) completed the study protocol and follow-up. Their mean height ( ± SD) increased from 131.3 ± 4.1 cm (-2.3 ± 0.7 SDS) at start of treatment to 159.8 ± 4.7 cm (-1.1 ± 0.7 SDS) at AH. In matched controls, height increased from 132.3 ± 4.2 cm (-2.4 ± 0.5 SDS) to 153.2 ± 3.4 cm (-2.1 ± 0.6 SDS) (p<0.001). AH surpassed initial PAH by 12.0 ± 2.6 cm in treated girls; and by 4.2 ± 3.6 cm in the controls (p<0.001). Most treated girls reached normal adult height (>-2SD) (87.5%) and 68.7% reached or superseded the target height (TH), which was the case in only a minority of the controls (37.5% and 6.2%, respectively) (p= 0.003 and 0.001). A serious adverse event possibly related to the treatment, was a fracture of the metatarsals. Conclusion: A four-year GH/GnRHa treatment in early pubertal girls with a poor PAH seems safe and results in a clinically relevant and statistically significant increase in AH compared with matched historical controls. Clinical trial registration: ClinicalTrials.gov, identifier NCT00840944.

Safety and Efficacy of Pediatric Growth Hormone Therapy: Results From the Full KIGS Cohort.

CONTEXT: The Kabi/Pfizer International Growth Database (KIGS) is a large, international database (1987-2012) of children treated with recombinant human growth hormone (rhGH) in real-world settings. OBJECTIVE: This work aimed to evaluate the safety and efficacy of rhGH from the full KIGS cohort. METHODS: Data were collected by investigators from children with growth disorders treated with rhGH (Genotropin [somatropin]; Pfizer). Safety was evaluated in all treated patients, and efficacy in those treated for 1 year or more. A subgroup included patients treated for 5 years or more (≥ 2 years prepubertal) who had reached near-adult height (NAH). Main outcomes included adverse events (AEs), serious AEs (SAEs), and height growth. RESULTS: The full KIGS cohort (N = 83 803 [58% male]) was treated for idiopathic GH deficiency (IGHD; 46.9%), organic GHD (10.0%), small for gestational age (SGA; 9.5%), Turner syndrome (TS; 9.2%), idiopathic short stature (ISS; 8.2%), and others (16.2%). Median rhGH treatment duration was 2.7 years and observation 3.1 years. SAEs occurred in 3.7% of patients and death in 0.4%. The most common SAEs were recurrence of craniopharyngioma (n = 151), neoplasm (n = 99), and cancer (n = 91); and scoliosis (n = 91). Median first-year delta height-SD score (SDS) (Prader) in prepubertal patients was 0.66 (IGHD), 0.55 (ISS), 0.58 (TS), and 0.71 (SGA). Median gains in NAH-SDS were 1.79 (IGHD), 1.37 (ISS), and 1.34 (SGA) for boys, and 2.07 (IGHD), 1.62 (ISS), 1.07 (TS), and 1.57 (SGA) for girls. CONCLUSION: Data from KIGS, the largest and longest running international database of rhGH-treated children, show that rhGH is safe and increases short-term height gain and adult height across GHD and non-GHD conditions.

Is a Two-Year Growth Response to Growth Hormone Treatment a Better Predictor of Poor Adult Height Outcome Than a First-Year Growth Response in Prepubertal Children With Growth Hormone Deficiency?

Objective: The first year response to growth hormone (GH) treatment is related to the total height gain in GH treated children, but an individual poor first year response is a weak predictor of a poor total GH effect in GH deficient (GHD) children. We investigated whether an underwhelming growth response after 2 years might be a better predictor of poor adult height (AH) outcome after GH treatment in GHD children. Design and methods: Height data of GHD children treated with GH for at least 4 consecutive years of which at least two prepubertal and who attained (near) (n)AH were retrieved from the Belgian Register for GH treated children (n = 110, 63% boys). In ROC analyses, the change in height (ΔHt) SDS after the first and second GH treatment years were tested as predictors of poor AH outcome defined as: (1) nAH SDS <-2.0, or (2) nAH SDS minus mid-parental height SDS <-1.3, or (3) total ΔHt SDS <1.0. The cut-offs for ΔHt SDS and its sensitivity at a 95% specificity level to detect poor AH outcome were determined. Results: Eleven percent of the cohort had a total ΔHt SDS <1.0. ROC curve testing of first and second years ΔHt SDS as a predictor for total ΔHt SDS <1.0 had an AUC >70%. First-year ΔHt SDS <0.41 correctly identified 42% of the patients with poor AH outcome at a 95% specificity level, resulting in respectively 5/12 (4.6%) correctly identified poor final responders and 5/98 (4.5%) misclassified good final responders (ratio 1.0). ΔHt SDS after 2 prepubertal years had a cut-off level of 0.65 and a sensitivity of 50% at a 95% specificity level, resulting in respectively 6/12 (5.5%) correctly identified poor final responders and 5/98 (4.5%) misclassified good final responders (ratio 1.2). Conclusion: In GHD children the growth response after 2 prepubertal years of GH treatment did not meaningfully improve the prediction of poor AH outcome after GH treatment compared to first-year growth response parameters. Therefore, the decision to re-evaluate the diagnosis or adapt the GH dose in case of poor response after 1 year should not be postponed for another year.

DNA Methylation Profiling and Genomic Analysis in 20 Children with Short Stature Who Were Born Small for Gestational Age.

PURPOSE: In a significant proportion of children born small for gestational age (SGA) with failure of catch-up growth, the etiology of short stature remains unclear after routine diagnostic workup. We wanted to investigate if extensive analysis of the (epi)genome can unravel the cause of growth failure in a significant portion of these children. PATIENTS AND METHODS: Twenty SGA children treated with GH because of short stature were selected from the BELGROW database of the Belgian Society for Pediatric Endocrinology and Diabetology for exome sequencing, single-nucleotide polymorphism (SNP) array and genome-wide methylation analysis to identify the (epi)genetic cause. First-year response to GH was compared with the response of SGA patients in the KIGS database. RESULTS: We identified (likely) pathogenic variants in 4 children (from 3 families) using exome sequencing and found pathogenic copy number variants in 2 probands using SNP array. In a child harboring a NSD1-containing microduplication, we identified a DNA methylation signature that is opposite to the genome-wide DNA methylation signature of Sotos syndrome. Moreover, we observed multilocus imprinting disturbances in 2 children in whom no other genomic alteration could be identified. Five of 6 children with a genetic diagnosis had an "above average" response to GH. CONCLUSIONS: The study indicates that a more advanced approach with deep genotyping can unravel unexpected (epi)genomic alterations in SGA children with persistent growth failure. Most SGA children with a genetic diagnosis had a good response to GH treatment.

Criteria for First-Year Growth Response to Growth Hormone Treatment in Prepubertal Children With Growth Hormone Deficiency: Do They Predict Poor Adult Height Outcome?

Objective: Several criteria for first-year growth response (FYGR) to growth hormone (GH) treatment have been proposed. We explored which FYGR criteria predicted best the final height outcome after GH treatment in prepubertal children with GH deficiency (GHD). Design and methods: Height data of 129 GHD children (83 boys) who attained adult height and had been treated with GH for at least 4 consecutive years with at least 1 year before pubertal onset, were retrieved from the Belgian GH Registry. The FYGR parameters were: (1) increase in height (ΔHt) SDS, (2) height velocity (HV) SDS, (3) ΔHV (cm/year), (4) index of responsiveness (IoR) in KIGS prediction models, (5) first-year HV SDS based on the KIGS expected HV curve (HV KIGS SDS), (6) near final adult height (nFAH) prediction after first-year GH treatment. Poor final height outcome (PFHO) criteria were: (1) total ΔHt SDS <1.0, (2) nFAH SDS <-2.0, (3) nFAH minus midparental height SDS <-1.3. ROC curve analyses were performed to define the optimal cut-off for FYGR parameters to predict PFHO. Only ROC curves with an area under the curve (AUC) of more than 70% were further analyzed. Results: Twelve, 22 and 10% of the children had respectively a total ΔHt SDS <1, nFAH SDS <-2, and nFAH minus midparental height SDS <-1.3. The AUC's ranged between 73 and 85%. The highest AUC was found for first-year ΔHt SDS to predict total ΔHt SDS <1, and predicted nFAH SDS to predict nFAH SDS <-2. The currently used FYGR criteria had low specificities and sensitivities to detect PFHO. To obtain a 95% specificity, the cut-off value (and sensitivity) of FYGR parameters were: ΔHt SDS <0.35 (40%), HV SDS <-0.85 (43%), ΔHV <1.3 cm/year (36%), IoR <-1.57 (17%), HV KIGS SDS <-0.83 (40%) to predict total ΔHt SDS <1; predicted nFAH SDS (with GH peak) <-1.94 (25%), predicted nFAH SDS (without GH peak) <-2.02 (25%) to predict nFAH SDS <-2. At these cut-offs, the amount of correctly diagnosed poor final responders equals the amount of false positives. Conclusion: First-year growth response criteria perform poorly as predictors of poor final height outcome after long-term GH treatment in prepubertal GHD children.

Treatment with Growth Hormone in Noonan Syndrome Observed during 25 Years of KIGS: Near Adult Height and Outcome Prediction.

BACKGROUND/AIMS: There is little information how rhGH treatment affects height in NS. This study aims to analyze data from the NS patients assembled in KIGS over 25 years. PATIENTS/METHODS: Of 613 (389 m/224 f) NS patients documented, 476 (302 m/174 f) were treated for 1 year, 237 (160 m/77 f) of which served to develop a 1st year height velocity (HV) prediction algorithm. One-hundred and forty (74 m/66 f) had reached near adult height (NAH). Factors affecting NAH on rhGH were determined. RESULTS: At the start of rhGH, the NAH groups were (median, m, f) 11.0 and 10.3 years, with a height SDS of -3.2 and -3.8 SDS (Prader), respectively. The total gain after 6.3 and 5.6 years on rhGH (0.27 and 0.30 mg/kg/week) was 1.2 and 1.3 SDS. Age at the start of rhGH (negative), height at the start of rhGH, rhGH dose, number of rhGH injections/wk and birth weight (all positive) explained 36% of the variability of 1st year HV. Height at the start of rhGH, 1st year growth on rhGH, birth weight, and gender explained 74% of the variability of NAH. Causes for rhGH treatment discontinuation and adverse events were also analyzed. CONCLUSION: rhGH treatment increases NAH in NS. Prediction algorithms may optimize treatment in the future.

Poor growth response during the first year of growth hormone treatment in short prepubertal children with growth hormone deficiency and born small for gestational age: a comparison of different criteria.

BACKGROUND: There is no consensus on the definition of poor growth response after the first year of growth hormone (GH) treatment. We determined the proportion of poor responders identified by different criteria in children with GH deficiency (GHD) and born small for gestational age (SGA). The second aim was to analyze the IGF-1 response in poor growth responders. METHODS: First-year height data of 171 SGA and 122 GHD children who remained prepubertal during the first GH treatment year were retrieved from the BESPEED database and analyzed. Criteria for poor first-year response/responsiveness were: change in height (∆Ht) SDS<0.3 or<0.5, height velocity (HV) SDS<0.5 or <1 based on the population reference, HV SDS<- 1 based on the KIGS expected HV curve (HV Ranke SDS), studentized residual (SR) <- 1 in the KIGS first-year prediction model. RESULTS: ∆Ht SDS<0.5 gave the highest percentage poor responders (37% SGA, 26% GHD). Although % poor responders were comparable for ∆Ht SDS<0.3, HV SDS<+ 0.5, HV SDS<+ 1, SR<- 1, and HV Ranke SDS<- 1, these criteria did not always identify the same patients as poor responders. Among the poor growth responders 24% SGA and 14% GHD patients had an IGF-1 increase < 40%. CONCLUSIONS: The different response criteria yield high but comparable percentages poor responders, but identify different patients. This study does not provide evidence that one criterion is better than another. A limited IGF-1 generation is not the major reason for a poor growth response in the first year of GH treatment in SGA and GHD children. TRIAL REGISTRATION: Retrospectively registered.

Individualised growth response optimisation (iGRO) tool: an accessible and easy-to-use growth prediction system to enable treatment optimisation for children treated with growth hormone.

BACKGROUND: Growth prediction models (GPMs) exist to support clinical management of children treated with growth hormone (GH) for growth hormone deficiency (GHD), Turner syndrome (TS) and for short children born small for gestational age (SGA). Currently, no prediction system has been widely adopted. CONTENT: The objective was to develop a stand-alone web-based system to enable the widespread use of an 'individualised growth response optimisation' (iGRO) tool across European endocrinology clinics. A modern platform was developed to ensure compatibility with IT systems and web browsers. Seventeen GPMs derived from the KIGS database were included and tested for accuracy. SUMMARY: The iGRO system demonstrated prediction accuracy and IT compatibility. The observed discrepancies between actual and predicted height may support clinicians in investigating the reasons for deviations around the expected growth and optimise treatment. CONCLUSIONS: This system has the potential for wide access in endocrinology clinics to support the clinical management of children treated with GH for these three indications.

Validation of Prediction Models for Near Adult Height in Children with Idiopathic Growth Hormone Deficiency Treated with Growth Hormone: A Belgian Registry Study.

BACKGROUND/AIM: To validate prediction models for near final adult height (nFAH) by Ranke et al. [Horm Res Paediatr 2013;79:51-67]. METHODS: Height data of 127 (82 male) idiopathic growth hormone (GH)-deficient children, treated with GH until nFAH, were retrieved from the database of the Belgian Society for Pediatric Endocrinology and Diabetology (BESPEED). nFAH was predicted after first-year GH treatment, applying prediction models by Ranke et al. Bland-Altman plots and Clarke error grid analyses were performed to assess clinical significance of the differences between observed and predicted nFAH. RESULTS: In males, the predicted nFAH was higher than the observed nFAH (difference: 0.2 ± 0.7 SD; p < 0.01). In females, there was no significant difference. Bland-Altman analyses showed that the means of the differences between observed and predicted nFAH were close but not equal to zero, with overprediction for smaller heights and underprediction for taller heights. Clarke error grid analysis: in males, 59-61% of the predicted nFAH were within 0.5 SDS and 88% within 1.0 SDS from the observed nFAH; in females, 40-44% of the predicted nFAH were within 0.5 SDS and 76-78% within 1.0 SDS from the observed nFAH. CONCLUSION: Ranke's models accurately predicted nFAH in females and overpredicted nFAH in males by about 1.5 cm. In most individuals, the predicted nFAH was within 1 SDS of observed nFAH. These models can be of help in giving realistic expectations of adult height. © 2016 S. Karger AG, Basel.

Genetic screening of Congenital Short Bowel Syndrome patients confirms CLMP as the major gene involved in the recessive form of this disorder.

Congenital short bowel syndrome (CSBS) is an intestinal pediatric disorder, where patients are born with a dramatic shortened small intestine. Pathogenic variants in CLMP were recently identified to cause an autosomal recessive form of the disease. However, due to the rare nature of CSBS, only a small number of patients have been reported to date with variants in this gene. In this report, we describe novel inherited variants in CLMP in three CSBS patients derived from two unrelated families, confirming CLMP as the major gene involved in the development of the recessive form of CSBS.

A 2-year multicentre, open-label, randomized, controlled study of growth hormone (Genotropin®) treatment in very young children born small for gestational age: Early Growth and Neurodevelopment (EGN) Study.

OBJECTIVE: In Europe, growth hormone (GH) treatment for children born small for gestational age (SGA) can only be initiated after 4 years of age. However, younger age at treatment initiation is a predictor of favourable response. To assess the effect of GH treatment on early growth and cognitive functioning in very young (<30 months), short-stature children born SGA. DESIGN: A 2-year, randomized controlled, multicentre study (NCT00627523; EGN study), in which patients received either GH treatment or no treatment for 24 months. PATIENTS: Children aged 19-29 months diagnosed as SGA at birth, and for whom sufficient early growth data were available, were eligible. Patients were randomized (1:1) to GH treatment (Genotropin®, Pfizer Inc.) at a dose of 0·035 mg/kg/day by subcutaneous injection, or no treatment. MEASUREMENTS: The primary objective was to assess the change from baseline in height standard deviation score (SDS) after 24 months of GH treatment. RESULTS: Change from baseline in height SDS was significantly greater in the GH treatment vs control group at both month 12 (1·03 vs 0·14) and month 24 (1·63 vs 0·43; both P < 0·001). Growth velocity SDS was significantly higher in the GH treatment vs control group at 12 months (P < 0·001), but not at 24 months. There was no significant difference in mental or psychomotor development indices between the two groups. CONCLUSIONS: GH treatment for 24 months in very young short-stature children born SGA resulted in a significant increase in height SDS compared with no treatment.

Genetic and structural variation in the SH2B1 gene in the Belgian population.

OBJECTIVE: Animal studies, genome-wide association and genomic structural variation studies have identified the SH2B1 gene as a candidate gene for obesity. Therefore, we have designed an extensive mutation and copy number variation (CNV) analysis investigating the prevalence of genetic and structural variations in SH2B1 in the Belgian population. DESIGN AND METHODS: In the first part of this study, we performed a mutation screen for variants in the SH2B1 coding region in 581 obese children and adolescents and 433 healthy, lean individuals with high-resolution melting curve analysis followed by direct sequencing. In the second part of this study, Multiplex Amplicon Quantification (MAQ) analysis was used to identify CNVs in the distal SH2B1-containing chr.16p11.2 region in 421 obese children and adolescents with no developmental delay or behavioral phenotype. RESULTS: Mutation analysis resulted in the identification of fifteen rare non-synonymous heterozygous variants. Several of these were found both in lean and obese subjects, suggesting that these are neutral polymorphisms. However, six private, heterozygous, non-synonymous variations were present in obese children only. Furthermore, we also identified six missense variants solely in lean individuals. CNV analysis could not identify carriers of the distal 16p11.2 deletion in our population. CONCLUSION: Our mutation analysis has demonstrated that variation in the SH2B1 gene is frequent in both lean and obese groups, with distinctive variations being present on either side of the weight spectrum. Although the equal variation frequency does not immediately support disease causality, it cannot be excluded that some variations are weight-increasing or -decreasing. Further functional testing of the variants will be necessary to fully understand the impact of these variants on SH2B1. We were not able to detect carriers of the distal 16p11.2 deletion in our study population. As we excluded patients with developmental or behavioral problems, we suggest that in addition to obesity, the distal deletion might predispose for these traits. Further characterization of the phenotype is therefore necessary to clearly identify the phenotype of the distal 16p11.2 microdeletion syndrome.

Short Children with CHARGE Syndrome: Do They Benefit from Growth Hormone Therapy?

AIM: The aim of this study was to evaluate the response to recombinant growth hormone (GH) treatment in short children with CHARGE syndrome. PATIENTS: We identified 51 children (28 boys and 23 girls) in KIGS (Pfizer International Growth Database). The median chronological age was 7.6 years at the start of GH therapy and 13.2 years at the latest visit. Evaluation for GH deficiency (n = 33) was based on the following: peak GH level 7.3 µg/l and IGF-I level -2.01 standard deviation score (SDS). Sixteen subjects (9 boys) were followed longitudinally for 2 years. RESULTS: Birth length (median SDS, -0.47) and weight (-0.97) were slightly reduced. At the start of GH therapy, height was -3.6 SDS, BMI -0.7 SDS, and the GH dose was 0.26 mg/kg/week. At the latest visit after 2.7 years of GH therapy, height had increased to -2.2 SDS and BMI to -0.5 SDS. In the longitudinal group, height increased from -3.72 SDS at the start of GH therapy to -2.92 SDS after 1 year to -2.37 SDS after 2 years of therapy (start - 2 years: p < 0.05), height velocity increased from -1.69 to 2.98 to 0.95 SDS, and BMI and GH dose (mg/kg/week) remained almost unchanged. CONCLUSIONS: Our data show a positive effect of conventional doses of GH on short-term growth velocity for the longitudinal as well as for the total group, without any safety issues.

Reference curve for the first-year growth response to growth hormone treatment in prepubertal children with idiopathic growth hormone deficiency: validation of the KIGS first-year growth response curve using the Belgian Register for the Study of Growth and Puberty Problems.

BACKGROUND: Comparing observed and expected growth after first-year growth hormone (GH) therapy is useful for identifying a poor growth response to GH. AIM: To generate a first-year, age-specific growth response reference curve for prepubertal Belgian children with idiopathic growth hormone deficiency (iGHD) treated with a standard weight-adjusted GH dose and to compare this national reference with the response references derived from KIGS. SUBJECTS AND METHODS: First-year height data of 357 prepubertal children (240 males) with iGHD were analyzed. Smooth reference curves of first-year height velocity (HV) in relation to age were created. Differences with the KIGS targets were evaluated after z-score transformation. RESULTS: The observed first-year HVs were log-normal distributed by age and decreased significantly with age (p<0.001). No GH dose or gender effect was observed (p=0.5). Distance to target height, severity of GHD and occurrence of multiple pituitary hormone deficiencies had a positive effect (p<0.01) on the calculated HV SDS. When applying the KIGS targets for severe iGHD, mean HV SDS was close to zero (-0.09±0.84). CONCLUSION: The developed age-specific growth response curves enable rapid identification of poor response to first-year GH treatment in prepubertal iGHD children. Our results validate the published growth targets derived from the KIGS database.

Identification of mutations in the NUCB2/nesfatin gene in children with severe obesity.

Nesfatin-1 is the N-terminal fragment of nucleobindin-2 (NUCB2) that was identified as a novel satiety molecule in rodents. The protein is reported to exert anorexigenic effects and appears to play an important role in hypothalamic pathways regulating energy homeostasis and food intake. In this study, we hypothesized that mutations in the nesfatin encoding gene NUCB2 might cause obesity in humans. Therefore, we screened the entire coding region of the NUCB2 gene for mutations in a population of 471 obese children and adolescents. Mutation analysis of NUCB2 identified a total of seven sequence variants of which four were previously reported as polymorphisms. The remaining three variants included ex9+6G>C, L125H and K178X and were found in 3 unrelated individuals in the obese population only (0.6%). Biochemical experiments including ELISA and western blot were performed on plasma samples of the obese patient carrying the nonsense mutation K178X. However, neither NUCB2/nesfatin-1 immunoreactive plasma levels of the patient, nor expression of full length NUCB2 differed significantly from matched obese control individuals. In conclusion, we have identified the first genetic variants in the NUCB2 gene in obese individuals, although further functional characterization will be essential to verify disease causality of the mutations.

Insulin sensitivity modulates the growth response during the first year of high-dose growth hormone treatment in short prepubertal children born small for gestational age.

AIM: To study the relationship between insulin sensitivity and growth response in short children born small for gestational age (SGA) treated with growth hormone (GH). METHODS: Randomized, open-label, 24-month intervention study in 40 short prepubertal SGA children [age (mean ± SD) 5.3 ± 1.5 years], who either remained untreated (n = 20) or were treated with GH (66 µg/kg/day; n = 20). Changes in fasting glucose, insulin, quantitative insulin sensitivity check index (QUICKI), IGF-1 and leptin after 1 and 2 years were studied. RESULTS: Mean height SDS increased from -3.3 ± 0.7 to -2.3 ± 0.7 after 1 year, and to -1.9 ± 0.7 after 2 years of treatment. QUICKI decreased significantly (p = 0.008) in the first year of GH treatment and stabilized in the second year. Baseline QUICKI was positively associated (r = 0.40; p < 0.05) with the change in height SDS in the first year. CONCLUSION: Higher insulin sensitivity at the start of GH therapy is associated with greater first-year growth response to GH, and could be a promising parameter in selecting prepubertal short SGA children for GH treatment. However, this finding needs to be confirmed in larger studies.

In vitro recovery of ATP-sensitive potassium channels in ß-cells from patients with congenital hyperinsulinism of infancy.

OBJECTIVE: Congenital hyperinsulinism in infancy (CHI) is characterized by unregulated insulin secretion from pancreatic ß-cells; severe forms are associated with defects in ABCC8 and KCNJ11 genes encoding sulfonylurea receptor 1 (SUR1) and Kir6.2 subunits, which form ATP-sensitive K(+) (K(ATP)) channels in ß-cells. Diazoxide therapy often fails in the treatment of CHI and may be a result of reduced cell surface expression of K(ATP) channels. We hypothesized that conditions known to facilitate trafficking of cystic fibrosis transmembrane regulator (CFTR) and other proteins in recombinant expression systems might increase surface expression of K(ATP) channels in native CHI ß-cells. RESEARCH DESIGN AND METHODS: Tissue was isolated during pancreatectomy from eight patients with CHI and from adult cadaver organ donors. Patients were screened for mutations in ABCC8 and KCNJ11. Isolated ß-cells were maintained at 37°C or 25°C and in the presence of 1) phorbol myristic acid, forskolin and 3-isobutyl-1-methylxanthine, 2) BPDZ 154, or 3) 4-phenylbutyrate. Surface expression of functional channels was assessed by patch-clamp electrophysiology. RESULTS: Mutations in ABCC8 were detected for all patients tested (n = 7/8) and included three novel mutations. In five of eight patients, no changes in K(ATP) channel activity were observed under different cell culture conditions. However, in three patients, in vitro recovery of functional K(ATP) channels occurred. Here, we report the first cases of recovery of defective K(ATP) channels in human ß-cells using modified cell culture conditions. CONCLUSIONS: Our study establishes the principle that chemical modification of K(ATP) channel subunit trafficking could be of benefit for the future treatment of CHI.

Identification of three novel genetic variants in the melanocortin-3 receptor of obese children.

The melanocortin-3 receptor (MC3R), a G-protein-coupled receptor expressed in the hypothalamus, is a key component of the leptin-melanocortin pathway that regulates energy homeostasis. It is suggested that an MC3R defect leads to an increased feed efficiency, by which nutrients are partitioned preferentially into fat. In this study, we hypothesized that early-onset obesity could be induced by mutations in MC3R. To investigate this hypothesis, we screened the entire coding region of the MC3R gene for mutations in obese subjects. A total of 404 overweight and obese children and adolescents, 86 severely obese adults (BMI ≥40 kg/m²), and 150 normal-weight control adults were included. Besides three synonymous coding variations in the MC3R gene (S69S, L95L, I226I), we were able to identify three novel heterozygous, nonsynonymous, coding mutations (N128S, V211I, L299V) in three unrelated obese children. None of these mutations were found in any of the control subjects. Functional studies assessing localization and signaling properties of the mutant receptors provided proof for impaired function of the L299V mutated receptor, whereas no conclusive evidence for functional impairment of the N128S and V211I mutated receptors could be established. First, these results provide supporting evidence for a role of the MC3R gene in the pathogenesis of obesity in a small subset of patients. Second, they show that caution is called for the interpretation of newly discovered mutations in MC3R.

Sleep-disordered breathing: a new risk factor of suspected fatty liver disease in overweight children and adolescents?

INTRODUCTION: The aim of this retrospective study was to investigate if sleep-disordered breathing (SDB) was an independent predictor of suspected fatty liver disease in a clinical sample of overweight children and adolescents. MATERIALS AND METHODS: Consecutive overweight and obese children attending a pediatric obesity clinic underwent polysomnography, fasting blood sample, and abdominal ultrasound. RESULTS AND DISCUSSION: The respiratory disturbance index, percentage of total sleep time with SO2 < 90%, and SaO2nadir were associated with higher alanine amino-transferases (ALT) independent of abdominal obesity. Multiple logistic regression selected waist circumference (odds ratio = 1.05; p = 0.05) and SaO2nadir (odds ratio = 0.87; p = 0.03) as predictors of suggestive fatty liver disease, defined as ALT > 40 U/L and/or hyperechoic liver on abdominal ultrasound. This study supports the association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight children and adolescents. We recommend more research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnea on liver function parameters.