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

Background: 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.

[Innovative medical care concepts for adolescents with severe obesity]

There is no convincing, science-based treatment or care concept for adolescents with severe obesity in Germany or other countries. The affected young people have an increased risk of numerous somatic comorbidities (e.g. type 2 diabetes mellitus, orthopaedic disorders and sleep apnoea syndrome), mental disorders (e.g. depression and anxiety disorders, social phobia and self-harming behaviour), as well as social isolation (e.g. avoidance of school and unemployment), which develops due to functional impairments and stigmatisation. Despite the negative effects of severe obesity in adolescence, these young people are medically difficult to reach and treat. Only a small percentage of patients actively seek treatment.Aware of these difficulties, the German multi-centre Youth with Extreme Obesity (YES) Study (funded by the German Ministry of Education and Science; 01 GI 1120 A and B) was carried out between 2012 and 2019 with the aim of improving care concepts for this neglected group of young people. In our article, we show possible supply routes. These consist of accompanying the adolescents and treating their comorbidities, sustainable lifestyle interventions in a protected environment and treatment for weight reduction through bariatric surgery. The overriding goals for patients are an increase in self-esteem, early diagnosis and treatment of secondary diseases and integration into the training and labour market.

Methylphenidate in children with monogenic obesity due to LEPR or MC4R deficiency improves feeling of satiety and reduces BMI-SDS-A case series

BACKGROUND

The clinical phenotype of patients with monogenic obesity due to mutations in the leptin receptor (LEPR) or melanocortin 4 receptor (MC4R) gene is characterized by impaired satiety and hyperphagia, leading to extreme, sometimes life-threatening weight gain.

SUBJECTS/METHODS

In a case series, we analysed the effect of an off-label methylphenidate (MPH) use for 1 year as an individual treatment approach on eating behaviour (Child Eating Behaviour Questionnaire [CEBQ]), appetite (visual analogue scales) and body mass index (BMI) trajectories in five patients with severe obesity due to mutations in the LEPR (n = 3) or MC4R (n = 2) gene.

RESULTS

After 1 year use of MPH (20 mg/day divided in two to three doses), BMI (Δ BMI_T0-T1x¯ : -0.7 ± 0.9 kg/m² ), BMI standard deviation score (SDS) (Δ BMI-SDS_T0-T1x¯ : -0.32 ± 0.20), and %BMIP95 (Δ %BMIP95_T0-T1x¯ : -6.6 ± 7.8%) decreased. BMI-SDS velocity decreased from +0.17 ± 0.22 to -0.30 ± 0.20. Appetite and CEBQ subscale scores for "food responsiveness" and "enjoyment of food" decreased. We observed adverse effects with increase in self-reported frequency of disordered sleep, nervousness, hyperactivity, and tics.

CONCLUSIONS

The observed decrease in BMI trajectories with MPH use for one year is clinically meaningful in this group of patients, since the natural course would have been associated with a pronounced increase in BMI, leading to comorbidities and complications over time.

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

Background: 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.

Functional and Phenotypic Characteristics of Human Leptin Receptor Mutations

Several case series of extreme early-onset obesity due to mutations in the human leptin receptor (LEPR) gene have been reported. In this review we summarize published functional and phenotypic data on mutations in the human LEPR gene causing severe early-onset obesity. Additionally, we included data on six new cases from our obesity center. Literature research was performed using PubMed and OMIM. Functional relevance of mutations was estimated based on reported functional analysis, mutation size, and location, as well as phenotypic characteristics of affected patients. We identified 57 cases with 38 distinct LEPR mutations. We found severe early-onset obesity, hyperphagia, and hypogonadotropic hypogonadism as cardinal features of a complete loss of LEPR function. Other features, for example, metabolic disorders and recurring infections, were variable in manifestation. Obesity degree or other manifestations did not aggregate by genotype. Few patients underwent bariatric surgery with variable success. Most mutations occurred in the fibronectin III and cytokine receptor homology II domains, whereas none was found in cytoplasmic domain. In silico data were available for 25 mutations and in vitro data were available for four mutations, revealing residual activity in one case. By assessing provided information on the clinical phenotype, functional analysis, and character of the 38 mutations, we assume residual LEPR activity for five additional mutations. Functional in vitro analysis is necessary to confirm this assumption.

Food Addiction, High-Glycemic-Index Carbohydrates, and Obesity

BACKGROUND

Treatment success in obesity remains low, and recently food addiction has been delineated as an underlying etiologic factor with therapeutic relevance. Specifically, current treatment focuses on reduced food intake and increase of physical activity, whereas interventions for addiction encompass behavioral therapy, abstinence, and environmental interventions such as taxation, restrictions on advertising, and regulation of school menus.

CONTENT

Here, we reviewed the pertinent literature on food addiction with a specific focus on the role of high-glycemic-index carbohydrates in triggering addictive symptoms. Three lines of evidence support the concept of food addiction: (a) behavioral responses to certain foods are similar to substances of abuse; (b) food intake regulation and addiction rely on similar neurobiological circuits; (c) individuals suffering from obesity or addiction show similar neurochemical- and brain activation patterns.High-glycemic-index carbohydrates elicit a rapid shift in blood glucose and insulin levels, akin to the pharmacokinetics of addictive substances. Similar to drugs of abuse, glucose and insulin signal to the mesolimbic system to modify dopamine concentration. Sugar elicits addiction-like craving, and self-reported problem foods are rich in high-glycemic-index carbohydrates. These properties make high-glycemic-index carbohydrates plausible triggers for food addiction.

SUMMARY

We argue that food addiction is a plausible etiological factor contributing to the heterogeneous condition and phenotype of obesity. In at least a subset of vulnerable individuals, high-glycemic-index carbohydrates trigger addiction-like neurochemical and behavioral responses.

A Structured, Manual-Based Low-Level Intervention vs. Treatment as Usual Evaluated in a Randomized Controlled Trial for Adolescents with Extreme Obesity - the STEREO Trial

BACKGROUND

To compare efficacy and safety of a manual-based low-level psychological intervention with treatment as usual (weight loss treatment).

METHODS

A two-armed randomized controlled trial without blinding and computer-based stratified block randomization included adolescents and young adults (14.0-24.9 years) with a BMI ≥ 30 kg/m2 at five German university hospitals. Primary outcomes were adherence (participation rate ≥ 5/6 sessions) and quality of life (DISABKIDS-37) 6 months after randomization. Secondary outcomes included depression, self-esteem, and perceived stress scores.

RESULTS

Of 397 screened adolescents, 119 (mean BMI 40.4 ± 7.0 kg/m2, 49.6% female) were randomized to the manual-based low-level intervention (n = 59) or treatment as usual (n = 60). We observed no group difference for adherence (absolute risk reduction 0.4%, 95% CI -14.7% to 15.5%; p = 1.0) or health-related quality of life (score difference 8.1, 95% CI -2.1 to 18.3; p = 0.11). Among all secondary outcomes, we detected explorative evidence for an effect on the DISABKIDS-37 'social exclusion' subscale (score difference 15.5; 95% CI 1.6-29.4; p = 0.03). 18/19 adverse events occurred in 26 participants, none were classified as serious.

CONCLUSION

Adherence to a coping-oriented intervention was comparable to weight loss treatment, although it was weak in both interventions. Psychological interventions may help to overcome social isolation; further confirmation is required.

[Case series: BMI long courses in patients with extreme juvenile obesity. Short- and long-term success of long-term inpatient treatment]

BACKGROUND

Extreme obesity in adolescents is considered largely resistant to therapy. The aim of this study was to demonstrate the short- and long-term BMI histories of patients who have successfully participated in an inpatient weight loss program, and to look for factors influencing the very good success.

METHODS

For the case series 10 youths were selected, who participated in an inpatient weight reduction program for 6-12 months and who succeeded in reducing BMI for the short and for the long term. The inpatient weight reduction program was based on a lifestyle intervention. Information on BMI (kg/m(2)) per patient are available for time of baseline examination (T0, admission), final examination (T1, end of inpatient treatment) and follow-up (T2, 3-18 years after the beginning of the intervention). Socio-demographic data were collected within the first consultation (T0).

RESULTS

Mean BMI was 41.9 kg/m(2) (BMI-SDS: 3.22) at time of admission. It clearly decreased under therapy and continued decreasing after the end of inpatient treatment. At time of follow-up (T2) 9 patients had a BMI < 30 kg/m(2) and were not any longer rated as obese, 4 patients had normal weight (BMI: 18.5-24.9 g/m(2)). The majority of patients had at least one normal-weight parent, all families had an average or high socioeconomic status (SES) and the majority of young people attended school for at least 10 years. Occurrence of binge eating before the inpatient treatment was rejected by two thirds of patients.

CONCLUSIONS

The case series shows that there is a group of patients who have a clear and lasting decrease of BMI and thus benefit for the long term from an inpatient weight reduction program. In literature discussed predictors of long-term weight reduction such as normal weight of parents, high SES of parents and a high school education of the patients were observed in this selective group. In individual cases, a long-term inpatient therapy leading to lasting lifestyle changes should firstly be preferred to bariatric surgery.

Biologically inactive leptin and early-onset extreme obesity

Mutations in the gene encoding leptin (LEP) typically lead to an absence of circulating leptin and to extreme obesity. We describe a 2-year-old boy with early-onset extreme obesity due to a novel homozygous transversion (c.298G→T) in LEP, leading to a change from aspartic acid to tyrosine at amino acid position 100 (p.D100Y) and high immunoreactive levels of leptin. Overexpression studies confirmed that the mutant protein is secreted but neither binds to nor activates the leptin receptor. The mutant protein failed to reduce food intake and body weight in leptin-deficient ob/ob mice. Treatment of the patient with recombinant human leptin (metreleptin) rapidly normalized eating behavior and resulted in weight loss.

Monogenic forms of childhood obesity due to mutations in the leptin gene

Congenital leptin deficiency is a rare autosomal recessive monogenic obesity syndrome caused by mutations in the leptin gene. This review describes the molecular and cellular characteristics of the eight distinct mutations found so far in humans.

Plasma insulin levels in childhood are related to maternal factors--results of the Ulm Birth Cohort Study

AIMS

The cardiovascular risk factor profile of a child as well as the development of body weight are influenced by genetic and childhood factors. Circulating insulin concentrations reflect the metabolic cardiovascular risk and may trigger weight gain. We aimed at identifying parental and childhood factors which may influence fasting plasma insulin concentrations in children.

METHODS

The Ulm Birth Cohort study (UBCS) is a prospective birth cohort study. At baseline, birth characteristics, maternal pre-pregnancy body mass index (BMI) values as well as parental socioeconomic parameters were obtained. At the 8-yr follow-up examination, weights, heights, and fasting plasma insulin concentrations in n = 422 children and their parents were measured. Offspring of women with gestational diabetes mellitus were excluded from statistical analysis.

RESULTS

Fasting plasma insulin concentrations of children were significantly correlated with maternal pre-pregnancy BMI values (r = 0.16) as well as with maternal (r = 0.26) but not with paternal fasting plasma insulin concentrations (r = 0.11) at the 8-yr follow-up examination. The risk for high fasting plasma insulin concentrations (≥75th internal percentile) was 2.30 (1.34-3.92) in children who also had high plasma insulin concentrations in umbilical cord blood compared to children having lower plasma insulin concentrations (<75th internal percentile) in umbilical cord blood. In addition, we observed that children with high fasting plasma insulin concentrations at the age of 8 had an altered BMI trajectory in childhood, characterized by higher BMI values from the age of 1 onwards, compared to children with lower insulin concentrations.

CONCLUSION

Our observations support the hypothesis of perinatal programming of offspring insulin concentrations and BMI values by maternal pre-pregnancy BMI values.