Genetic Obesity and Bariatric Surgery Outcome in 1014 Patients with Morbid Obesity

Rare gene variants and weight loss at 10 years after sleeve gastrectomy and gastric bypass - a randomized clinical trial

BACKGROUND

Genetic background of severe obesity is inadequately understood. The effect of genetic factors on weight loss after metabolic bariatric surgery (MBS) has shown inconclusive results.

OBJECTIVES

To determine the prevalence of rare obesity-associated gene variants in a secondary analysis of a randomized clinical trial (RCT) comparing laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) for the treatment of severe obesity and examine their association with long-term weight loss at 10 years.

SETTING

University Hospital, Finland.

METHODS

Targeted sequencing panel was used to examine variants in 79 obesity-associated genes and 16p11.2 copy number variants. Weight loss was evaluated by percentage total weight loss (%TWL).

RESULTS

Out of 240 patients, 113 patients [mean body mass index 48.4 kg/m2, (6.8 standard deviation [SD]) kg/m2 and median age 49 (range 26-64) years, LSG n = 60, LRYGB n = 53] were available for this post-hoc study. We identified 7 rare heterozygous likely/suspected pathogenic (LP/SP) variants in SH2B1, PCSK1, DNMT3A, BDNF, and AFF4 in 6 patients (5.3%), 5 heterozygous variants of uncertain significance in PLXNA4, PLXNA2, NRP1, and SEMA3D in 5 patients (4.4%), heterozygous Bardet-Biedl syndrome variants in 3 patients (2.7%), and PCKS1 risk allele p.Asn221Asp in 9 patients (8.0%). The patients with LP/SP variants had earlier age of obesity onset (P = .0089) and higher %TWL (P = .0446) compared with patients without LP/SP variants.

CONCLUSIONS

There were LP/SP pathogenic variants in 5% of the patients supporting the potential benefits of genetic testing to optimize targeted therapies in the future. Despite deleterious gene defects the long-term MBS outcome can be favorable.

Cross-sectional analysis of eating disorder risk and risk correlates in candidates for bariatric surgery from the BariPredict cohort

Bariatric surgery is an effective intervention for managing obesity. Persons with obesity are a high-risk population for eating disorders (ED), and these can negatively impact perioperative and long-term outcomes of surgery. We aim to understand prevalence and correlates of ED in preintervention patients, identifying those needing psychological support. Baseline cross-sectional analysis of 275 patients of the BariPredict cohort (NCT06480058), a study to assess predictors of long-term surgery outcomes. Psychological assessments were conducted using SCOFF, KUAS, and BDI tools. Data were analyzed for prevalence of high ED risk and for associations of clinical, biological and demographic factors. Mean age was 38.5 years, mean BMI was 42.3 kg/m², with 62.5% being female. 65.8% of patients had a SCOFF score ≥ 2 indicating high ED risk. Class II obesity (p < 0.05), younger age (p < 0.01), and higher depression (p < 0.01) were associated with ED risk in a logistic regression adjusted for age, obesity class, diabetes, HbA1c, depression and anxiety scores. We report high preintervention prevalence of ED, with a risk profile corresponding to BMI of 35-39.9 Kg/m2 in younger adults with concurrent depression. This patient profile should be prioritized for psychological assessment and support to potentially improve outcomes of bariatric surgery.

Influence of the Brain-Derived Neurotrophic Factor Gene Polymorphism on Weight Loss Following Intragastric Balloon Intervention: A Cross-Sectional Study

Background and Aim

There is noticeable heterogeneity in weight loss outcomes following intragastric balloon (IGB) treatment, with average weight loss ranging between 11% to 15% of total body weight. Genetic variations associated with obesity have been found to influence weight loss response, however such variations are limited. Therefore, the aim of this study is to investigate the impact of the obesity associated brain-derived neurotrophic factor (BDNF) gene polymorphism rs11030104 with weight loss outcomes following IGB treatment.

Methods

In this cross-sectional study, BDNF rs11030104 was analysed in 106 individuals who underwent intragastric balloon treatment. Weight loss metrics were evaluated at the three-month follow-up: percentage of total weight loss (%TWL), percentage of excess weight loss (%EWL), and percentage of body mass index loss (%EBMIL). The effects of additive and dominant genetic models were evaluated. Both linear and logistic regression were applied to assess associations between rs11030104 genotypes and weight loss metrics.

Results

A total of 71 participants completed the 3-month follow-up assessment (loss to follow-up: 33%). This study found a significant association between the BDNF rs11030104 polymorphism and weight loss. A-allele carriers showed a better response to IGB treatment. Individuals carrying the AA genotype were found to have a greater %TWL than those carrying the GG genotype at 3 months post-IGB treatment (11.05% vs 5.09%, p=0.003).

Conclusion

Our results suggest that BDNF rs11030104 influences the response to weight loss after IGB treatment and therefore could be added to the growing list of genetic variants that predict greater weight loss response.

Investigating genetic variants in early-onset obesity through exome sequencing: A retrospective cohort study

OBJECTIVE

This study aimed to examine clinical data and analyze exome sequencing (ES) findings in children diagnosed with early-onset obesity.

METHODS

We screened children presenting with severe (body mass index-standard deviation score >3) and early-onset (<7 years) obesity using ES. Participants were categorized into either the "no variant identified" group or the "variant identified" group, facilitating the exploration of correlations between clinical-demographic characteristics and genetic mutations linked to early-onset obesity. The functional implications of identified variants were assessed through in silico analyses.

RESULTS

Of the patients, 32 (35.5 %) possessed one or more mutations in pathways associated with obesity, all of which were heterozygous and patients with more than two obesity-associated variants were more obese. This cohort included 29 novel mutations distinct to our study population, 7 previously reported pathogenic variants, two instances of uniparental disomy, and one mitochondrial hotspot mutation. Variants in the SH2B1 gene emerged as a prevalent genetic determinant of obesity within our group, accounting for 16.6 % of cases. Statistical evaluations showed no significant differences in demographic attributes between the two groups.

CONCLUSION

Exome sequencing proves to be an instrumental approach for uncovering new variants and broadening the spectrum of mutations in early-onset obesity among children. Concurrently, further functional studies, both in vitro and in vivo, are crucial to elucidate the contributions of these variants to obesity's pathogenesis.

Precision Medicine in Bariatric Procedures

Obesity is a multi-factorial disease that is influenced by genetic, epigenetic, and environmental factors. Precision medicine is a practice wherein prevention and treatment strategies take individual variability into account. It involves using a variety of factors including deep phenotyping using clinical, physiologic, and behavioral characteristics, 'omics assays (eg, genomics, epigenomics, transcriptomics, and microbiomics among others), and environmental factors to devise practices that are individualized to subsets of patients. Personalizing the therapeutic modality to the individual can lead to enhanced effectiveness and tolerability. The authors review advances in precision medicine made in the field of bariatrics and discuss future avenues and challenges.

Setmelanotide: A Melanocortin-4 Receptor Agonist for the Treatment of Severe Obesity Due to Hypothalamic Dysfunction

Obesity is a silent global pandemic. It is a condition associated with multiple risk factors and adverse outcomes that arise from the intertwined relationship between environmental factors and genetics. The genetic factors that cause phenotypic expression are variable. Monogenic obesity is a severe early-onset and rarer form of obesity, which presents with co-morbidities such as abnormal feeding behaviour. Monogenic obesity causes impaired weight regulation in the hypothalamus due to defects in the leptin-melanocortin signalling pathway. The emergence of a new therapeutic treatment, the melanocortin-4 receptor agonist setmelanotide (originally RM-493), has represented a breakthrough in the management of monogenic obesity and has raised hope in managing complex obesity. This review provides an overview of the setmelanotide trials that have taken place, as well as its mechanism of action, side effects and weight loss outcomes that led to its approval in the treatment of pro-opiomelanocortin (POMC) deficiency and proprotein convertase subtilisin/kexin type 1 (PCSK1) deficiency. It also explores setmelanotide's role in other genetic forms of obesity, such as hypothalamic obesity, Prader-Willi syndrome, Alström syndrome and other rare genetic conditions that are being investigated. This review aims to help to understand the pathophysiology of genetic obesity and aid in future treatment options for people with severe, complex genetic obesity.

Updates on Rare Genetic Variants, Genetic Testing, and Gene Therapy in Individuals With Obesity

PURPOSE OF REVIEW

The goal of this paper is to aggregate information on monogenic contributions to obesity in the past five years and to provide guidance for genetic testing in clinical care.

RECENT FINDINGS

Advances in sequencing technologies, increasing awareness, access to testing, and new treatments have increased the utilization of genetics in clinical care. There is increasing recognition of the prevalence of rare genetic obesity from variants with mean allele frequency < 5% -new variants in known genes as well as identification of novel genes- causing monogenic obesity. While most of these genes are in the leptin melanocortin pathway, those in adipocytes may also contribute. Common variants may contribute either to higher lifetime tendency for weight gain or provide protection from monogenic obesity. While specific genetic mutations are rare, these segregate in individuals with early-onset severe obesity; thus, collectively genetic etiologies are not as rare. Some genetic conditions are amenable to targeted treatment. Research into the discovery of novel genetic causes as well as targeted treatment is growing over time. The utility of therapeutic strategies based on the genetic risk of obesity is an advancing frontier.

Mutations in the leptin-melanocortin pathway and weight loss after bariatric surgery: a systematic review and meta-analysis

OBJECTIVE

The objective of this meta-analysis was to quantify the overall effects of gene mutations in the leptin-melanocortin pathway on short- and long-term weight loss after bariatric surgery.

METHODS

MEDLINE, PubMed, and Embase were searched, and data were analyzed using ReviewManager (RevMan) version 5.4. The datasets were divided into two subgroups based on postoperative time, and the outcome measure was the percentage of total weight loss. Meta-regression analysis was performed, and the outcome was presented as the weighed mean difference of percentage of total weight loss.

RESULTS

The results showed that patients with mutations in the leptin-melanocortin pathway experienced 3.03% lower total weight loss after bariatric surgery (mean difference, -3.03; 95% CI: -3.63 to -2.44), mainly reflected in lower long-term postoperative weight loss (mean difference, -3.43; 95% CI: -4.09 to -2.77), whereas mutation carriers exhibited a magnitude of short-term postoperative weight loss that was similar to patients without such mutations (total difference value, -1.13; 95% CI: -2.57 to 0.31).

CONCLUSIONS

Mutations in leptin-melanocortin pathway genes reduce long-term weight loss after bariatric surgery, whereas this effect may not be reflected during the period of rapid weight loss within 12 months. These genetic variants increase the difficulties in maintaining patients' long-term weight loss.

The effect of significant weight loss after bariatric surgery on echocardiographic indices: an observational study focusing on left ventricular deformation by 2D speckle echocardiography and right ventricular size

BACKGROUND

Obesity is a known risk factor for atherosclerosis and cardiac disease.

HYPOTHESIS

This study evaluated the effect of significant weight loss following bariatric surgery on myocardial deformation indices and right ventricular size (RV). This was a prospective cohort study. Morbid obese patients scheduled for bariatric surgery from July 2017 to February 2018 at Firoozgar Hospital were included in our study and referred for transthoracic echocardiography at Rajaie Cardiovascular Medical and Research Center.

RESULTS

Thirty-four patients entered the study. The absolute value of global longitudinal strain (GLS) at baseline, 3, and 6 months after surgery was 17.42 ± 2.94%, 18.24 ± 3.09%, and 19.52 ± 2.78%, respectively, with a statistically significant difference from baseline to after six months (P value < 0.001). The absolute value of global circumferential strain (GCS) at baseline, 3, and 6 months after surgery was 20.14 ± 4.22%, 23.32 ± 4.66%, and 24.53 ± 4.52%, respectively, with statistically significant changes (P value < 0.001) from baseline to three months and from baseline to six months and no significant difference from three months to six months. A significant decrease was reported in mechanical dispersion of circumferential strain (38.05 ± 23.81-23.37 ± 20.86 ms, P value = 0.006) 6 months after surgery. Right ventricular size three- and six-month post-surgery showed a significant decrease relative to baseline echocardiography.

CONCLUSIONS

Bariatric surgery could enhance cardiac function, as proven by 2D speckle echocardiography. Changes in RV size may be related to weight loss and should be considered when assessing patients who have undergone bariatric surgery.

Physiological Appetite Regulation and Bariatric Surgery

Obesity remains a common metabolic disorder and a threat to health as it is associated with numerous complications. Lifestyle modifications and caloric restriction can achieve limited weight loss. Bariatric surgery is an effective way of achieving substantial weight loss as well as glycemic control secondary to weight-related type 2 diabetes mellitus. It has been suggested that an anorexigenic gut hormone response following bariatric surgery contributes to weight loss. Understanding the changes in gut hormones and their contribution to weight loss physiology can lead to new therapeutic treatments for weight loss. Two distinct types of neurons in the arcuate hypothalamic nuclei control food intake: proopiomelanocortin neurons activated by the anorexigenic (satiety) hormones and neurons activated by the orexigenic peptides that release neuropeptide Y and agouti-related peptide (hunger centre). The arcuate nucleus of the hypothalamus integrates hormonal inputs from the gut and adipose tissue (the anorexigenic hormones cholecystokinin, polypeptide YY, glucagon-like peptide-1, oxyntomodulin, leptin, and others) and orexigeneic peptides (ghrelin). Replicating the endocrine response to bariatric surgery through pharmacological mimicry holds promise for medical treatment. Obesity has genetic and environmental factors. New advances in genetic testing have identified both monogenic and polygenic obesity-related genes. Understanding the function of genes contributing to obesity will increase insights into the biology of obesity. This review includes the physiology of appetite control, the influence of genetics on obesity, and the changes that occur following bariatric surgery. This has the potential to lead to the development of more subtle, individualised, treatments for obesity.

A comprehensive review of genetic causes of obesity

BACKGROUND

Obesity is a multifactorial chronic disease with a high, increasing worldwide prevalence. Genetic causes account for 7% of the cases in children with extreme obesity.

DATA SOURCES

This narrative review was conducted by searching for papers published in the PubMed/MEDLINE, Embase and SciELO databases and included 161 articles. The search used the following search terms: "obesity", "obesity and genetics", "leptin", "Prader-Willi syndrome", and "melanocortins". The types of studies included were systematic reviews, clinical trials, prospective cohort studies, cross-sectional and prospective studies, narrative reviews, and case reports.

RESULTS

The leptin-melanocortin pathway is primarily responsible for the regulation of appetite and body weight. However, several important aspects of the pathophysiology of obesity remain unknown. Genetic causes of obesity can be grouped into syndromic, monogenic, and polygenic causes and should be assessed in children with extreme obesity before the age of 5 years, hyperphagia, or a family history of extreme obesity. A microarray study, an analysis of the melanocortin type 4 receptor gene mutations and leptin levels should be performed for this purpose. There are three therapeutic levels: lifestyle modifications, pharmacological treatment, and bariatric surgery.

CONCLUSIONS

Genetic study technologies are in constant development; however, we are still far from having a personalized approach to genetic causes of obesity. A significant proportion of the affected individuals are associated with genetic causes; however, there are still barriers to its approach, as it continues to be underdiagnosed. Video Abstract (MP4 1041807 KB).

High Prevalence of Positive Genetic Obesity Variants in Postoperative Bariatric Surgery Patients with Weight Regain Presenting for Medical Obesity Intervention

INTRODUCTION

Genetic obesity susceptibility in postoperative bariatric surgery weight regain (PBSWR) remains largely unexplored.

METHODS

A retrospective case series of adult (N = 27) PBSWR patients who had undergone genetic obesity testing was conducted between Sept. 2020 and March 2022.

PRIMARY OUTCOME

frequency of genetic variants in patients experiencing weight regain following bariatric surgery.

SECONDARY OUTCOMES

prevalence of obesity-related comorbidities, nadir BMI achieved post-bariatric surgery, and percent total body weight loss (%TBWL) achieved with obesity pharmacotherapies.

RESULTS

Heterozygous mutations were identified in 22 (81%) patients, with the most prevalent mutations occurring in CEP290, RPGR1P1L, and LEPR genes (3 patients each). Median age was 56 years (interquartile range (IQR) 46.8-65.5), 88% female. Types of surgery were 67% RYGB, 19% SG, 4% gastric band, and 13% revisions. Median nadir BMI postoperatively was 34.0 kg/m2 (IQR 29.0-38.5). A high prevalence of metabolic derangements was noted; patients presented median 80 months (IQR 39-168.5) postoperative for medical weight management with 40% weight regain. BMI at initiation of anti-obesity medication (AOMs) was 41.7 kg/m2 (36.8-44.4). All received AOM and required at least 3 AOMs for weight regain. Semaglutide (N = 21), topiramate (N = 14), and metformin (N = 12) were most prescribed. Median %TBWL for the cohort at the first, second, and third visit was 1.7, 5.0, and 6.5 respectively. Fourteen (52%) achieved 5%TBWL, 10 (37%) achieved 10%TBWL, and 4 (15%) achieved 15%TBWL with combination AOMs and supervised medical intervention.

CONCLUSION

An unusually high prevalence of genetic obesity variants in PBSWR was found, warranting further research.

Type 2 Diabetes Remission in Patients with Heterozygous Variants in the Leptin-Melanocortin Pathway after Roux-en-Y Gastric Bypass: A Matched Case-Control Study

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is associated with a high rate of type 2 diabetes (T2D) remission. Carriers of heterozygous variants in the leptin-melanocortin pathway (LMP) are more likely to experience weight recurrence after RYGB. Our aim was to investigate if carrier status and associated weight regain affects the rate of T2D remission after RYGB.

METHODS

Carriers of LMP variants with a diagnosis of T2D prior to RYGB (N = 16) were matched to non-carriers (N = 32) based on sex, age, and BMI. We assessed for post-operative T2D remission status post-surgery on a yearly basis, for up to 15 years. Our primary endpoint was the proportion of patients achieving T2D remission at 1 year. We conducted a survival analysis for all patients that achieved remission at least at one time-point to evaluate for maintenance of T2D remission by using a log-rank test.

RESULTS

Both carriers and non-carriers had similar baseline and procedural characteristics. The proopiomelanocortin gene in the LMP pathway had the most variants (n = 5, 31%). Carriers had a lower total body weight loss percentage at nadir (28.7% ± 6.9) than non-carriers (33.7% ± 8.8, p = 0.04). The proportion of patients achieving T2D remission at 1 year was 68.8% for carriers and 71.9% for non-carriers (p = 1.0). Survival curves for maintenance of first remission were similar for both groups (p = 0.73), with a median survival of 8 years for both carriers and non-carriers.

CONCLUSIONS

Despite inferior weight loss outcomes at nadir, carriers had similar T2D remission rates when compared to non-carriers. Weight-independent metabolic benefits of RYGB might contribute to this observation.

A novel pathogenic variant in MRAP2 in an obese patient with successful outcome of bariatric surgery

Mutations in genes encoding proteins located in the leptin/melanocortin pathway have been identified in the rare cases of genetic obesities. Heterozygous variants of MRAP2, encoding a G coupled-protein receptor accessory protein implicated in energy control notably via the melanocortin-4 receptor, have been recently identified. A 24-year-old patient with early-onset severe obesity (body mass index [BMI]: 64 kg/m2) associated with hypertension, respiratory complications, nonalcoholic fatty liver disease, and type 2 diabetes was referred to our department. Sleeve gastrectomy was successful. A new heterozygous variant in MRAP2 (NM_138409.4: c.154G>C/p.G52R) variant was identified in the patient DNA. Functional assessment confirmed that this new variant was pathogenic. We report a new pathogenic loss-of-function mutation in MRAP2 in a patient suffering from a severe multicomplicated obesity. This confirms the metabolic phenotype in patients with this monogenic form of obesity. Longer follow-up will be necessary. Our finding will allow a personalized medicine.

Functional Characterization of MC4R Variants in Chinese Morbid Obese Patients and Weight Loss after Bariatric Surgery

Mutations in MC4R are the most common genetic cause of obesity. In the reported Chinese morbid obesity cohort, 10 out of 59 harbor six MC4R variants, including Y35C, T53I, V103I, R165W, G233S, and C277X, among which V103I has a relatively high frequency, while other five variants are rare in the population. The prevalence of MC4R carriers in Chinese morbid obese patients (body mass index ≥ 45 kg m-2 ) is detected as 16.9% in this study. R165W and C277X are loss-of-function variants. The patient with R165W achieves excess weight loss (%EWL) as high as 20.6% and 50.3% at 1 and 8 months after surgery, respectively. G233S is reported for the first time in Asia obese population. The patient harboring G233S has a %EWL as 23.3% one month postsurgery. It is concluded that morbid obese patients with rare MC4R variants can benefit from metabolic surgery. More importantly, the choice of surgery procedure and MC4R variant should be taken into consideration for personalized treatment. In the future, a larger size cohort, accompanied with regular and longer follow-up, would be helpful.

Genetics: A Starting Point for the Prevention and the Treatment of Obesity

Obesity is a common, serious, and costly disease. More than 1 billion people worldwide are obese-650 million adults, 340 million adolescents, and 39 million children. The WHO estimates that, by 2025, approximately 167 million people-adults and children-will become less healthy because they are overweight or obese. Obesity-related conditions include heart disease, stroke, type 2 diabetes, and certain types of cancer. These are among the leading causes of preventable, premature death. The estimated annual medical cost of obesity in the United States was nearly $173 billion in 2019 dollars. Obesity is considered the result of a complex interaction between genes and the environment. Both genes and the environment change in different populations. In fact, the prevalence changes as the result of eating habits, lifestyle, and expression of genes coding for factors involved in the regulation of body weight, food intake, and satiety. Expression of these genes involves different epigenetic processes, such as DNA methylation, histone modification, or non-coding micro-RNA synthesis, as well as variations in the gene sequence, which results in functional alterations. Evolutionary and non-evolutionary (i.e., genetic drift, migration, and founder's effect) factors have shaped the genetic predisposition or protection from obesity in modern human populations. Understanding and knowing the pathogenesis of obesity will lead to prevention and treatment strategies not only for obesity, but also for other related diseases.

The implications of defining obesity as a disease: a report from the Association for the Study of Obesity 2021 annual conference

Unlike various countries and organisations, including the World Health Organisation and the European Parliament, the United Kingdom does not formally recognise obesity as a disease. This report presents the discussion on the potential impact of defining obesity as a disease on the patient, the healthcare system, the economy, and the wider society. A group of speakers from a wide range of disciplines came together to debate the topic bringing their knowledge and expertise from backgrounds in medicine, psychology, economics, and politics as well as the experience of people living with obesity. The aim of their debate was not to decide whether obesity should be classified as a disease but rather to explore what the implications of doing so would be, what the gaps in the available data are, as well as to provide up-to-date information on the topic from experts in the field. There were four topics where speakers presented their viewpoints, each one including a question-and-answer section for debate. The first one focused on the impact that the recognition of obesity could have on people living with obesity regarding the change in their behaviour, either positive and empowering or more stigmatising. During the second one, the impact of defining obesity as a disease on the National Health Service and the wider economy was discussed. The primary outcome was the need for more robust data as the one available does not represent the actual cost of obesity. The third topic was related to the policy implications regarding treatment provision, focusing on the public's power to influence policy. Finally, the last issue discussed, included the implications of public health actions, highlighting the importance of the government's actions and private stakeholders. The speakers agreed that no matter where they stand on this debate, the goal is common: to provide a healthcare system that supports and protects the patients, strategies that protect the economy and broader society, and policies that reduce stigma and promote health equity. Many questions are left to be answered regarding how these goals can be achieved. However, this discussion has set a good foundation providing evidence that can be used by the public, clinicians, and policymakers to make that happen.

Clinical, genetic, and epidemiological survey of Polish children and adolescents with severe obesity: A study protocol of the Polish-German study project on severe early-onset obesity

Severe early-onset obesity (SEOO) in children is a common feature of monogenic obesity. Nowadays, mutations in at least 50 genes are known to be related to monogenic obesity, and many others are tested. Part of them is involved in the leptin-proopiomelanocortin pathway. The aim of the project is to establish the Polish database of severely obese children and adolescents and to evaluate the prevalence of monogenic forms of obesity in this cohort, with a special focus on leptin-proopiomelanocortin pathway abnormalities. The secondary project aim is to identify new population-specific mutations in obesity-related genes in severely obese Polish children and adolescents. This is a prospective multi-center clinical study performed in four Polish centers. The estimated sample size is 500 patients aged 1-18 years, with severe obesity, hyperphagia, and food-seeking behaviors. In each patient, the medical history regarding the obesity duration in the patient and obesity and its complication existence in the family will be taken. Next, the questionnaire regarding the symptom characteristic of specific mutations, which we are going to test, will be performed. Hyperphagia will be assessed on the basis of age-specific questionnaires. The physical examination with anthropometric measurement, basic biochemical and hormonal tests, and leptin and biologically active leptin measurements will be performed. Finally, genetic analysis will be performed using next-generation sequencing with sequencing libraries prepared to include obesity-related genes. The genotyping findings will be confirmed with the use of classic sequencing (Sanger's method). In the future, the pathogenicity of new mutations in obesity-related genes identified in our cohort is planned to be confirmed by functional testing in vitro. Nowadays, there are no data regarding the prevalence of severe obesity or monogenic obesity in Polish children. This project has the potential to improve understanding of obesity etiology and may contribute to implementing attribute mutation-specific treatment. Moreover, it may lead to a finding of new, population-specific mutations related to SEOO.

Higher Waist Hip Ratio Genetic Risk Score Is Associated with Reduced Weight Loss in Patients with Severe Obesity Completing a Meal Replacement Programme

Background: A better understanding of the influence of genetic factors on the response to lifestyle interventions in people with obesity may allow the development of more personalised, effective and efficient therapeutic strategies. We sought to determine the influence of six obesity-related genetic risk scores on the magnitude of weight lost by patients with severe obesity who completed a dietary intervention. Methods: In this single-centre prospective cohort study, participants with severe and complicated obesity who completed a 24-week, milk-based meal replacement programme were genotyped to detect the frequency of common risk alleles for obesity and type 2 diabetes-related traits. Genetic risk scores (GRS) for six of these traits were derived. Participants with a potentially deleterious monogenic gene variant were excluded from the analysis. Results: In 93 patients completing the programme who were not carrying a known obesity-related gene mutation, 35.5% had diabetes, 53.8% were female, mean age was 51.4 ± 11 years, mean body mass index was 51.5 ± 8.7 and mean total weight loss percent at 24 weeks was 16 ± 6.3%. The waist-hip ratio (WHR) GRS was inversely associated with percentage total weight loss at 24 weeks (adjusted β for one standard deviation increase in WHR GRS -11.6 [-23.0, -0.3], p = 0.045), and patients in the lowest tertile of WHR GRS lost more weight. Conclusions: Patients with severe and complicated obesity with a genetic predisposition to central fat accumulation had less weight loss in a 24-week milk-based meal replacement programme, but there was no evidence for influence from the five other obesity-related genetic risk scores on the response to dietary restriction.

Screening of non-syndromic early-onset child and adolescent obese patients in terms of LEP, LEPR, MC4R and POMC gene variants by next-generation sequencing

OBJECTIVES

Non-syndromic monogenic obesity is a rare cause of early-onset severe obesity in the childhood period. The aim of this study was to screen four obesity related genes (LEP, LEPR, MC4R and POMC) in children and adolescents who had severe, non-syndromic early onset obesity.

METHODS

Next-generation sequencing of all exons in LEP, LEPR, MC4R and POMC was performed in 154 children and adolescents with early onset severe obesity obesity.

RESULTS

Fifteen different variants in nineteen patients were identified with a variant detection rate of 12.3%. While six different heterozygous variants were observed in MC4R gene (10/154 patients; 6.5%), five different variants in POMC gene (four of them were heterozygous and one of them was homozygous) (6/154 patients; 3.9%) and four different homozygous variants in LEPR gene (3/154 patients; 1.9%) were described. However, no variants were detected in the LEP gene. The most common pathogenic variant was c.496G>A in MC4R gene, which was detected in four unrelated patients. Six novel variants (6/15 variants; 40%) were described in seven patients. Four of them including c.233C>A and c.752T>C in MC4R gene and c.761dup and c.1221dup in LEPR gene were evaluated as pathogenic or likely pathogenic.

CONCLUSIONS

In conclusion, MC4R variants are the most common genetic cause of monogenic early-onset obesity, consistent with the literature. The c.496G>A variant in MC4R gene is highly prevalent in early-onset obese patients.

Effects of Heterozygous Variants in the Leptin-Melanocortin Pathway on Roux-en-Y Gastric Bypass Outcomes: a 15-Year Case-Control Study

INTRODUCTION

Heterozygous variants in the leptin-melanocortin pathway are associated with obesity. However, their effect on the long-term outcomes after Roux-en-Y gastric bypass (RYGB) is still unknown.

METHODS

In this matched case-control study, 701 participants from the Mayo Clinic Biobank with a history of RYGB were genotyped. Sixty-three patients had a heterozygous variant in the leptin-melanocortin pathway. After excluding patients with potential confounders, carriers were randomly matched (on sex, age, body mass index [BMI], and years since surgery) with two non-carrier controls. The electronic medical record of carriers and matched non-carriers was reviewed for up to 15 years after RYGB.

RESULTS

A total of 50 carriers and 100 matched non-carriers with a history of RYGB were included in the study. Seven different genes (LEPR, PCSK1, POMC, SH2B1, SRC1, MC4R, and SIM1) in the leptin-melanocortin pathway were identified. At the time of surgery, the mean age was 50.8 ± 10.6 years, BMI 45.6 ± 7.3 kg/m², and 79% women. There were no differences in postoperative years of follow-up, Roux limb length, or gastric pouch size between groups. Fifteen years after RYGB, the percentage of total body weight loss (%TBWL) in carriers was - 16.6 ± 10.7 compared with - 28.7 ± 12.9 in non-carriers (diff = 12.1%; 95% CI, 4.8 to 19.3) and the percentage of weight regain after maximum weight loss was 52.7 ± 29.7 in carriers compared with 29.8 ± 20.7 in non-carriers (diff = 22.9%; 95% CI, 5.3 to 40.5). The nadir %TBWL was lower - 32.1 ± 8.1 in carriers compared with - 36.8 ± 10.4 in non-carriers (diff = 4.8%; 95% CI 1.8 to 7.8).

CONCLUSIONS

Carriers of a heterozygous variant in the leptin-melanocortin pathway have a progressive and significant weight regain in the mid- and long-term after RYGB. Genotyping patients experiencing significant weight regain after RYGB could help implement multidisciplinary and individualized weight loss interventions to improve weight maintenance after surgery.

Familial early-onset obesity in Turkish children: variants and polymorphisms in the melanocortin-4 receptor (MC4R) gene

OBJECTIVES

Genetic factors have a key role in childhood obesity with higher rates in children than adults. Among the monogenic types of non-syndromic obesity, melanocortin-4 receptor (MC4R) deficiency is the most frequent cause. Beside pathogenic variants, single-nucleotide polymorphisms in MC4R gene are also associated with lower energy expenditure. The aim of this study was to estimate the frequency of MC4R variants and polymorphisms in a cohort of Turkish children and adolescents with severe early-onset obesity, and to understand the clinical features of patients.

METHODS

Patients, 1-17 years of age, with the onset of obesity before 10 years of age and a body mass index (BMI) standard deviation score (SDS) of >2.3, and who had a family history of early-onset obesity in at least one of their first-degree relatives were included in the study. Beside routine blood tests genetic analyses for MC4R gene were performed.

RESULTS

Analyses of MC4R revealed previously known variations in three (3.5%) patients, and pathogenic polymorphisms related with obesity in four (4.7%) patients. BMI SDS values were between 2.8 and 5.5 SDS in the pathogenic variant carrier group, and 2.8-4.9 SDS in the polymorphism group. Mean BMI SDS in variant-negative group was 3.4 ± 0.82.

CONCLUSIONS

Investigation of the MC4R in individuals with early-onset obesity and presence of obesity first-degree relatives is important. Hypertension is a rare comorbidity compared to other causes. Contrary to studies reporting that insulin resistance was absent or very rare, we found it as a frequent finding in both pathogenic variants and polymorphisms of MC4R.

Mutations in melanocortin-4 receptor: From fish to men

Melanocortin-4 receptor (MC4R), expressed abundantly in the hypothalamus, is a critical regulator of energy homeostasis, including both food intake and energy expenditure. Shortly after the publication in 1997 of the Mc4r knockout phenotypes in mice, including increased food intake and severe obesity, the first mutations in MC4R were reported in humans in 1998. Studies in the subsequent two decades have established MC4R mutation as the most common monogenic form of obesity, especially in early-onset severe obesity. Studies in animals, from fish to mammals, have established the conserved physiological roles of MC4R in all vertebrates in regulating energy balance. Drug targeting MC4R has been recently approved for treating morbid genetic obesity. How the MC4R can be exploited for animal production is highly worthy of active investigation.

The Obesogenic and Glycemic Effect of Bariatric Surgery in a Family with a Melanocortin 4 Receptor Loss-of-Function Mutation

We report the long-term response to bariatric surgery in a singular family of four adolescents with severe obesity (41–82 kg/m2), homozygous for the C271R loss-of-function mutation in the melanocortin 4 receptor (MC4R), and three adults heterozygous for the same mutation. All patients had similar sociodemographic backgrounds and were followed for an average of 7 years. Three of the four homozygous patients regained their full weight (42–77 kg/m2), while the fourth lost weight but remained obese with a body mass index of 60 kg/m2. Weight regain was associated with relapse of most comorbidities, yet hyperglycemia did not relapse or was delayed. A1c levels were reduced in homozygous and heterozygous patients. The long-term follow-up data on this very unique genetic setting show that weight loss and amelioration of obesity following bariatric surgery require active MC4R signaling, while the improvement in glycemia is in part independent of weight loss. The study validates animal models and demonstrates the importance of biological signaling in the regulation of weight, even after bariatric surgery.

Critical review of bariatric surgical outcomes in patients with Prader-Willi syndrome and other hyperphagic disorders

OBJECTIVE

The aim of this study was to review bariatric procedure outcomes among patients with Prader-Willi syndrome (PWS), melanocortin 4 receptor (MC4R) mutations, Bardet-Biedl syndrome, and hypothalamic obesity.

METHODS

Systematic published literature review used the following search terms: "Prader-Willi syndrome," "Bardet-Biedl syndrome," "hyperphagia," "bariatric surgery," "MC4R"/"melanocortin 4 receptor", "hypothalamic obesity," and "bariatric procedure." Information collected included demographics, genetics, anthropometry, procedure type, outcomes, and complications, with inclusion of case series and clinical reports given the rarity of the disorders. For PWS, postoperative weight-change percentage and BMI up to 14 years following surgery were analyzed using general linear mixed models, with descriptive outcomes for other conditions.

RESULTS

A total of 54 publications were identified, with variable follow-up periods for 202 patients (114 with PWS, 43 with MC4R mutations, 7 with Bardet-Biedl syndrome, and 38 with hypothalamic obesity) among bariatric procedures. Weight loss of patients with PWS was greatest within 1 year of surgery, with weight-change percentage not significantly different from 0 at 5 years. Long-term results in other conditions were variable and featured suboptimal weight loss and increased reoperation risk.

CONCLUSIONS

Bariatric procedures among hyperphagic individuals, including those with PWS, report variable results and outcomes. Benefits of bariatric surgery may be less durable in hyperphagic disorders in comparison with other patients with severe obesity.

The Impact of Bariatric Surgery on Bone Health: State of the Art and New Recognized Links

Bariatric surgery (BS) is the most effective therapy for severe obesity, which improves several comorbidities (such as diabetes, hypertension, dyslipidemia, among others) and results in marked weight loss. Despite these consensual beneficial effects, sleeve gastrectomy and Roux-en-Y gastric bypass (the two main bariatric techniques) have also been associated with changes in bone metabolism and progressive bone loss. The objective of this literature review is to examine the impact of bariatric surgery on bone and its main metabolic links, and to analyze the latest findings regarding the risk of fracture among patients submitted to bariatric surgery.

Low-frequency Coding Variants Associated With Body Mass Index Affect the Success of Bariatric Surgery

CONTEXT

A recent study identified 14 low-frequency coding variants associated with body mass index (BMI) in 718 734 individuals predominantly of European ancestry.

OBJECTIVE

We investigated the association of 2 genetic scores (GS) with i) the risk of severe/morbid obesity, ii) BMI variation before weight-loss intervention, iii) BMI change in response to an 18-month lifestyle/behavioral intervention program, and iv) BMI change up to 24 months after bariatric surgery.

METHODS

The 14 low-frequency coding variants were genotyped or sequenced in 342 French adults with severe/morbid obesity and 574 French adult controls from the general population. We built risk and protective GS based on 6 BMI-increasing and 5 BMI-decreasing low-frequency coding variants that were polymorphic in our study.

RESULTS

While the risk GS was not associated with severe/morbid obesity status, BMI-decreasing low-frequency coding variants were significantly less frequent in patients with severe/morbid obesity than in French adults from the general population. Neither the risk nor the protective GS was associated with BMI before intervention in patients with severe/morbid obesity, nor did they affect BMI change in response to a lifestyle/behavioral modification program. The protective GS was associated with a greater BMI decrease following bariatric surgery. The risk and protective GS were associated with a higher and lower risk of BMI regain after bariatric surgery.

CONCLUSION

Our data indicate that in populations of European descent, low-frequency coding variants associated with BMI in the general population also affect the outcomes of bariatric surgery in patients with severe/morbid obesity.

Long-Term Weight Outcome After Bariatric Surgery in Patients with Melanocortin-4 Receptor Gene Variants: a Case-Control Study of 105 Patients

INTRODUCTION

Pathogenic heterozygous MC4R variants are associated with hyperphagia and variable degrees of obesity. Several research groups have reported short-term weight loss outcomes after bariatric surgery in a few patients with MC4R variants, but lack of longer-term data prevents evidence-based clinical decision-making.

MATERIALS AND METHODS

Bariatric surgery patients with heterozygous (likely) pathogenic MC4R variants, from three collaborating centers in the Netherlands, France, and the UK, were compared to matched controls (matched 2:1 for age, sex, preoperative BMI, surgical procedure, and diabetes mellitus, but without MC4R mutations). Weight loss and regain outcomes up to 6 years of follow-up were compared.

RESULTS

At 60 months of follow-up after RYGB, cases with MC4R variants showed weight regain with a mean of 12.8% (± 10.4 SD) total weight loss (TWL) from nadir, compared to 7.9% (± 10.5 SD) in the controls (p = 0.062). Among patients receiving SG, the cases with MC4R variants experienced inferior weight loss (22.6% TWL) during the first year of follow-up compared to the controls (29.9% TWL) (p = 0.010).

CONCLUSIONS

This multicenter study reveals inferior mid-term weight outcomes of cases with MC4R variants after SG, compared to RYGB. Since adequate weight loss outcomes were observed after RYGB, this procedure would appear to be an appropriate surgical approach for this group. However, the pattern of weight regain seen in cases with MC4R variants after both RYGB and SG highlights the need for pro-active lifelong management to prevent relapse, as well as careful expectation management.

Rare genetic causes of obesity: diagnosis and management in clinical care

Rare genetic forms of obesity are linked to impaired energy balance (i.e., eating behaviour and energy expenditure) involving hypothalamic pathways. More than 60 genes coding for proteins located in the hypothalamic leptin/melanocortin pathway contribute to the development of these rare forms of obesity. The ambition of the French National Protocol for the Diagnosis and Care (PNDS) of Obesity of Rare Causes was to establish practical recommendations for assessment and management at all ages. This report is available on the website of the French Health Authority (HAS). In addition to severe obesity, patients often display obesity-related comorbidities and neuropsychological/psychiatric disorders. These complex conditions make clinical management particularly challenging. Early diagnosis is critical for the organization of coordinated specialized multidisciplinary care, with mandatory interaction between caregivers, social partners and families. Strategies to prevent aggravation of obesity consist in limiting access to food, establishing a reassuring daily eating environment, and the practice of sustained adapted supervised daily physical activity. The implementation of genetic diagnosis in clinical practice now enables a personalized medicine approach with access to new drug therapies, and improves the analysis of the risk/benefit ratio of bariatric surgery.

Implication of Heterozygous Variants in Genes of the Leptin-Melanocortin Pathway in Severe Obesity

CONTEXT

Unlike homozygous variants, the implication of heterozygous variants on the leptin-melanocortin pathway in severe obesity has not been established.

OBJECTIVE

To describe the frequency, the phenotype, and the genotype-phenotype relationship for heterozygous variants in LEP, LEPR, POMC, and PCSK1 in severe obesity.

METHODS

In this retrospective study, genotyping was performed on at least 1 of the LEP, LEPR, POMC, and PCSK1 genes in 1486 probands with severe obesity (600 children, 886 adults). The phenotype was collected in 60 subjects with heterozygous variants and 16 with homozygous variants. We analyzed variant frequency, body mass index (BMI), age of obesity onset, food impulsivity, and endocrine abnormalities.

RESULTS

The frequency of subjects with homozygous variants was 1.7% (n = 26), and 6.7% (n = 100) with heterozygous variants. Adults with homozygous variants had a higher BMI (66 vs 53 kg/m2, P = .015), an earlier onset of obesity (0.4 vs 5.4 years, P < .001), more often food impulsivity (83% vs 42%, P = .04), and endocrine abnormalities (75% vs 26%, P < .01). The BMI was higher for subjects with high-impact heterozygous variants (61 vs 50 kg/m², P = .045) and those with a second heterozygous variant on the pathway (65 vs 49 kg/m², P < .01). In children, no significant differences were found for the age of obesity onset and BMI.

CONCLUSION

Heterozygous variants in LEP, LEPR, POMC, and PCSK1 are frequent in severe obesity and sometimes associated with a phenotype close to that of homozygotes. These data suggest a systematic search for variants in severe early-onset obesity, to discuss therapy that targets this key pathway.

A Systematic Review of Genetic Correlates of Weight Loss After Bariatric Surgery

This systematic review synthesized research evaluating the relationship between genetic predictors and weight loss after bariatric surgery. Fifty-seven studies were identified that examined single genes or genetic risk scores. Uncoupling protein (UCP) rs660339 was associated with excess weight loss after surgery in 4 of 6 studies. The most commonly assessed genes were fat mass and obesity-associated (FTO) gene (n = 10) and melanocortin-4 receptor (MC4R) (n = 14). Both were inconsistently related to weight loss. Genetic risk scores predicted weight loss in 6 of 7 studies. This evidence suggests the potential of using genetic variants and genetic risk scores to predict the amount of weight loss anticipated after bariatric surgery and identify patients who may be at risk for suboptimal weight reduction.

Genetic markers of abdominal obesity and weight loss after gastric bypass surgery

Background

Weight loss after bariatric surgery varies widely between individuals, partly due to genetic differences. In addition, genetic determinants of abdominal obesity have been shown to attenuate weight loss after dietary intervention with special attention paid to the rs1358980-T risk allele in the VEGFA locus. Here we aimed to test if updated genetic risk scores (GRSs) for adiposity measures and the rs1358980-T risk allele are linked with weight loss following gastric bypass surgery.

Methods

Five hundred seventy six patients with morbid obesity underwent Roux-en-Y gastric bypass. A GRS for BMI and a GRS for waist-hip-ratio adjusted for BMI (proxy for abdominal obesity), respectively, were constructed. All patients were genotyped for the rs1358980-T risk allele. Associations between the genetic determinants and weight loss after bariatric surgery were evaluated.

Results

The GRS for BMI was not associated with weight loss (β = -2.0 kg/100 risk alleles, 95% CI -7.5 to 3.3, p = 0.45). Even though the GRS for abdominal obesity was associated with an attenuated weight loss response adjusted for age, sex and center (β = -14.6 kg/100 risk alleles, 95% CI -25.4 to -3.8, p = 0.008), it was not significantly associated with weight loss after adjustment for baseline BMI (β = -7.9 kg/100 risk alleles, 95% CI -17.5 to 1.6, p = 0.11). Similarly, the rs1358980-T risk allele was not significantly associated with weight loss (β = -0.8 kg/risk allele, 95% CI -2.2 to 0.6, p = 0.25).

Discussion

GRSs for adiposity derived from large meta-analyses and the rs1358980-T risk allele in the VEGFA locus did not predict weight loss after gastric bypass surgery. The association between a GRS for abdominal obesity and the response to bariatric surgery may be dependent on the association between the GRS and baseline BMI.

Long-term outcomes of bariatric surgery in patients with bi-allelic mutations in the POMC, LEPR, and MC4R genes

BACKGROUND

Gene mutations in the leptin-melanocortin signaling cascade lead to hyperphagia and severe early onset obesity. In most cases, multimodal conservative treatment (increased physical activity, reduced caloric intake) is not successful to stabilize body weight and control hyperphagia.

OBJECTIVES

To examine bariatric surgery as a therapeutic option for patients with genetic obesity.

SETTING

Three major academic, specialized medical centers.

METHODS

In 3 clinical centers, we retrospectively analyzed the outcomes of bariatric surgery performed in 8 patients with monogenic forms of obesity with bi-allelic variants in the genes LEPR (n = 5), POMC (n = 2), and MC4R (n = 1).

RESULTS

In this group of patients with monogenic obesity, initial bariatric surgery was performed at a median age of 19 years (interquartile range [IQR], 16-23.8 yr). All patients initially experienced weight loss after each bariatric surgery, which was followed by substantial weight regain. In total, bariatric surgery led to a median maximum reduction of body weight of -21.5 kg (IQR, -36.3 to -2.9 kg), median percent excess weight loss (%EWL) of -47.5 %EWL (IQR, -57.6 to -28.9 %EWL). This body weight reduction was followed by median weight regain of 24.1 kg (IQR: 10.0 to 42.0 kg), leading to a final weight change of -24.2 % EWL (IQR: -37.6 to -5.4 %EWL) after a maximum duration of 19 years post surgery. In one patient, bariatric surgery was accompanied by significant complications, including vitamin deficiencies and hernia development.

CONCLUSION

The indication for bariatric surgery in patients with monogenic obesity based on bi-allelic gene mutations and its benefit/risk balance has to be evaluated very cautiously by specialized centers. Furthermore, to avoid an unsuccessful operation, preoperative genetic testing of patients with a history of early onset obesity might be essential, even more since novel pharmacological treatment options are expected.

Characteristics and resolution of hypertension in obese African American bariatric cohort

Weight reduction continues to be first-line therapy in the treatment of hypertension (HTN). However, the long-term effect of bariatric malabsorptive surgical techniques such as Roux-en-Y Gastric Bypass (RYGB) surgery in the management of hypertension (HTN) is less clear. African Americans (AA) are disproportionately affected by obesity and hypertension and have inconsistent outcomes after bariatric surgery (BS). Despite a plethora of bariatric literature, data about characteristics of a predominantly AA bariatric hypertensive cohort including hypertension in obese (HIO) are scarce and underreported. The aims of this study were, (1) to describe the preoperative clinical characteristics of HIO with respect to HTN status and age, and (2) to identify predictors of HTN resolution one year after RYGB surgery in an AA bariatric cohort enrolled at the Howard University Center for Wellness and Weight Loss Surgery (HUCWWS). In the review of 169 AA bariatric patients, the average BMI was 48.50 kg/m2 and the average age was 43.86 years. Obese hypertensive patients were older (46 years vs. 37.89 years; p < .0001); had higher prevalence of diabetes mellitus (DM, 43.09% vs. 10.87%; p < .0001) and dyslipidemia (38.2% vs. 13.04%; p 0.002). Hypertensive AA who were taking ≥ 2 antihypertensive medications prior to RYGB were 18 times less likely to experience HTN resolution compared to hypertensive AA taking 0-1 medications, who showed full or partial response. Also, HIO was less likely to resolve after RYGB surgery in patients who needed ≥ 2 antihypertensive medications prior to surgical intervention.

Characteristics and resolution of hypertension in obese African American bariatric cohort

Weight reduction continues to be first-line therapy in the treatment of hypertension (HTN). However, the long-term effect of bariatric malabsorptive surgical techniques such as Roux-en-Y Gastric Bypass (RYGB) surgery in the management of hypertension (HTN) is less clear. African Americans (AA) are disproportionately affected by obesity and hypertension and have inconsistent outcomes after bariatric surgery (BS). Despite a plethora of bariatric literature, data about characteristics of a predominantly AA bariatric hypertensive cohort including hypertension in obese (HIO) are scarce and underreported. The aims of this study were, (1) to describe the preoperative clinical characteristics of HIO with respect to HTN status and age, and (2) to identify predictors of HTN resolution one year after RYGB surgery in an AA bariatric cohort enrolled at the Howard University Center for Wellness and Weight Loss Surgery (HUCWWS). In the review of 169 AA bariatric patients, the average BMI was 48.50 kg/m2 and the average age was 43.86 years. Obese hypertensive patients were older (46 years vs. 37.89 years; p < .0001); had higher prevalence of diabetes mellitus (DM, 43.09% vs. 10.87%; p < .0001) and dyslipidemia (38.2% vs. 13.04%; p 0.002). Hypertensive AA who were taking ≥ 2 antihypertensive medications prior to RYGB were 18 times less likely to experience HTN resolution compared to hypertensive AA taking 0-1 medications, who showed full or partial response. Also, HIO was less likely to resolve after RYGB surgery in patients who needed ≥ 2 antihypertensive medications prior to surgical intervention.

Diagnostic and therapeutic odyssey of two patients with compound heterozygous leptin receptor deficiency

BACKGROUND

Rare genetic variations in the leptin-melanocortin signalling pathway can severely impair appetite regulation and cause extreme obesity in early childhood.

CASE PRESENTATION

Our case reports describe the diagnostic and therapeutic procedures in a girl as well as in a non-related boy of non-consanguineous, German parents with severe early-onset obesity, pronounced hyperphagia, and permanent food-seeking behaviour. Excessive weight gain within the first year of life initiated extensive diagnostics without finding a causal diagnosis. Furthermore, a wide range of intensive, interdisciplinary, and behavioural therapies for weight control were unsuccessful. Prior to bariatric surgery, the 18-year-old girl and the 14-year-old boy reached a BMI of 67.7 kg/m2 and 55.2 kg/m2, respectively. However, even surgical outcomes were unsatisfactory. A subsequently initiated genetic analysis including sequencing of the leptin receptor gene revealed compound heterozygous variants as a cause of the severe early-onset obesity in both patients (c.2598-3_2607delTAGAATGAAAAAG and c.2227 T>C; c.1874G>A and c.2051A>C). Both patients were enrolled in the clinical study RM-493-015 and treated with melanocortin receptor agonist setmelanotide. Currently, they are still on setmelanotide treatment in the extension trial RM-493-022.

CONCLUSION

Our case report illustrates the urgent necessity of early genetic diagnostics in children with severe early-onset obesity to avoid frustrating and potentially damaging therapies. Thus, genetic examination should precede bariatric surgery. In the future, several pharmacological therapies will be available for some forms of monogenetic obesity.

Use of sleeve gastrectomy in adolescents and young adults with severe obesity

PURPOSE OF REVIEW

The prevalence of pediatric obesity and its associated complications is increasing around the world. Treatment of obesity is challenging and metabolic and bariatric surgery (MBS) is currently the most effective treatment for this condition. At this time, vertical sleeve gastrectomy (VSG) is the most commonly performed bariatric procedure in adolescents. However, knowledge regarding the efficacy, safety, and durability of VSG in adolescents is still evolving. This review summarizes the most recent updates in the field of MBS particularly VSG in adolescents.

RECENT FINDINGS

MBS is recommended to treat moderate to severe obesity, especially when complicated by comorbidities. The use of VSG for weight loss is increasing among adolescents and produces similar weight loss at five years in both adolescents and adults. The physiologic mechanisms causing weight loss after VSG are multifactorial and still being investigated. The complication rate after VSG ranges between 0 and 17.5%.

SUMMARY

VSG appears to be a well-tolerated and effective procedure in adolescents. However, it continues to be underutilized despite the increasing prevalence of moderate to severe obesity in adolescents. It is thus important to educate providers regarding its benefits and safety profile.

Bariatric Surgery for Monogenic Non-syndromic and Syndromic Obesity Disorders

PURPOSE OF REVIEW

The global prevalence of obesity has increased rapidly over the last decades, posing a severe threat to human health. Currently, bariatric surgery is the most effective therapy for patients with morbid obesity. It is unknown whether this treatment is also suitable for patients with obesity due to a confirmed genetic defect (genetic obesity disorders). Therefore, this review aims to elucidate the role of bariatric surgery in the treatment of genetic obesity.

RECENT FINDINGS

In monogenic non-syndromic obesity, an underlying genetic defect seems to be the most important factor determining the efficacy of bariatric surgery. In syndromic obesity, bariatric surgery result data are scarce, and even though some promising follow-up results have been reported, caution is required as patients with more severe behavioral and developmental disorders might have poorer outcomes. There is limited evidence in support of bariatric surgery as a treatment option for genetic obesity disorders; hence, no strong statements can be made regarding the efficacy and safety of these procedures for these patients. However, considering that patients with genetic obesity often present with life-threatening obesity-related comorbidities, we believe that bariatric surgery could be considered a last-resort treatment option in selected patients.

Identifying underlying medical causes of pediatric obesity: Results of a systematic diagnostic approach in a pediatric obesity center

Background

Underlying medical causes of obesity (endocrine disorders, genetic obesity disorders, cerebral or medication-induced obesities) are thought to be rare. Even in specialized pediatric endocrinology clinics, low diagnostic yield is reported, but evidence is limited. Identifying these causes is vital for patient-tailored treatment.

Objectives

To present the results of a systematic diagnostic workup in children and adolescents referred to a specialized pediatric obesity center.

Methods

This is a prospective observational study. Prevalence of underlying medical causes was determined after a multidisciplinary, systematic diagnostic workup including growth charts analysis, extensive biochemical and hormonal assessment and genetic testing in all patients.

Results

The diagnostic workup was completed in n = 282 patients. Median age was 10.8 years (IQR 7.7–14.1); median BMI +3.7SDS (IQR +3.3-+4.3). In 54 (19%) patients, a singular underlying medical cause was identified: in 37 patients genetic obesity, in 8 patients cerebral and in 9 patients medication-induced obesities. In total, thirteen different genetic obesity disorders were diagnosed. Obesity onset <5 years (p = 0.04) and hyperphagia (p = 0.001) were indicators of underlying genetic causes, but only in patients without intellectual disability (ID). Patients with genetic obesity with ID more often had a history of neonatal feeding problems (p = 0.003) and short stature (p = 0.005). BMI-SDS was not higher in patients with genetic obesity disorders (p = 0.52). Patients with cerebral and medication-induced obesities had lower height-SDS than the rest of the cohort.

Conclusions

To our knowledge, this is the first study to report the results of a systematic diagnostic workup aimed at identifying endocrine, genetic, cerebral or medication-induced causes of pediatric obesity. We found that a variety of singular underlying causes were identified in 19% of the patients with severe childhood obesity. Because of this heterogeneity, an extensive diagnostic approach is needed to establish the underlying medical causes and to facilitate disease-specific, patient-tailored treatment.

High-fat diet increased NADPH-oxidase-related oxidative stress and aggravated LPS-induced intestine injury

AIMS

Lipopolysaccharide (LPS)-induced intestinal injury is a common clinical feature of sepsis. Aggravated inflammation and higher sensitivity to infection are associated with high-fat diet (HFD) in patients with type 2 diabetes and/or obesity. However, the mechanism by which HFD exacerbates LPS-induced intestinal injury has not been elucidated. This study aims to examine the effects of HFD on intestinal injury induced by LPS and the underlying mechanism.

MAIN METHODS

Mice were fed with HFD or regular chow for 12weeks and were then challenged with LPS. Vas2870 was administered to mice that received HFD before the initiation of the diet. The levels of tight junction protein expression, oxidative stress, organ injury, and nicotinamide adenine dinucleotide phosphate (NADPH)-associated proteins were assessed periodically.

KEY FINDINGS

LPS treatment resulted in severe intestinal pathological injury and increased oxidative stress, evidenced by significantly increased serum diamine oxidase, reactive oxygen species, malondialdehyde, and intestinal fatty acid binding protein contents. Additionally, a decrease in tight junction protein expression was observed, indicating a loss of tight junction integrity. LPS treatment induced the expression of Nox2 and Nox4. All the effects were more severe in HFD mice. Treatment with vas2870 conferred protection against LPS-induced intestinal injury in HFD-fed mice, partially reduced oxidative stress, and rescued the expression of tight junction proteins.

CONCLUSION

HFD aggravated LPS-induced intestine injury through exacerbating intestinal Nox-related oxidative stress, which led to a loss of the integrity of tight junctions and consequently increased intestinal permeability.

Melanocortin 4 receptor (MC4R) gene variants in children and adolescents having familial early-onset obesity: genetic and clinical characteristics

Melanocortin 4 receptor gene plays an important role in food intake, energy balance, and weight control. The autosomal dominantly inherited MC4R variants cause obesity by causing hyperphagia and decreased sense of satiety. Homozygous variants are rarely reported, and they cause earlier/severe obesity. Our objective is to determine the MC4R gene variant frequency in children and adolescents with familial early-onset obesity. One hundred thirty-nine children and adolescents (57 girls/82 boys) whose weight increase started before the age of 5 years and who had early-onset obesity in at least one of their first-degree relatives were included in the study. Obesity is defined as body mass index (BMI) of ≥ 95th percentile, and as extreme obesity is defined if the BMI ≥ 120% of the 95th percentile or ≥ 35 kg/m². Children having genetic syndromes associated with obesity and mental retardation or taking drugs that promote changes in eating behavior or weight were excluded from the study. Coding region of the MC4R gene was sequenced by using the Illumina MiSeq Next Generation Sequencing System. The mean age of the patients was 7.3 ± 3.7 years, and the mean BMI SDS was 3.7 ± 0.7. While 118 patients (85%) were prepubertal, 21 patients (15%) were pubertal. Seven different variants were identified in 12 patients by giving a variant detection rate of 8.6%, of these five were previously identified missense variants p.N274S, p.S136F, p.V166I, p.R165W, and p.I291SfsX10. One homozygous variant p.I291SfsX10 (c.870delG) was detected in a severely obese 2-year-old boy, and other variants were heterozygous. Two novel variants were found: p.M200del and p.S188L. By using the in silico analysis software, these novel variants were predicted to be disease causing.Conclusion: MC4R gene variants are quite common in childhood obesity in Turkish population. Screening the variants in MC4R gene is necessary in patients with severe childhood-onset obesity. In such patients, comorbidities of obesity can be seen from early years. What is known • The frequency of MC4R mutations in obese patients was approximately 0-6.3%. What is new • In obese Turkish pediatric population, unlike other European countries, MC4R gene variants are quite common as we found a variant rate of 8.6% • We believe it is necessary to screen the variants in MC4R gene in patients with severe childhood-onset obesity and who had early-onset obesity in at least one of their first-degree relatives in Turkish population.