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Purpose: SH2B1 gene encodes an important adaptor protein to receptor tyrosine kinases or cytokine receptors associated with Janus kinases. This gene has been associated with the structural and functional modulation of neurons and other cells, and impacts on energy and glucose homeostasis. Several studies suggested that alterations in this gene are strong candidates for the development of obesity. However, only a few studies have screened SH2B1 point variants in individuals with obesity. Therefore, the aim of this study was to investigate the prevalence of SH2B1 variants in a Brazilian cohort of patients with severe obesity and candidates to bariatric surgery., Methods: The cohort comprised 122 individuals with severe obesity, who developed this phenotype during childhood. As controls, 100 normal-weight individuals were included. The coding region of SH2B1 gene was screened by Sanger sequencing., Results: A total of eight variants were identified in SH2B1, of which p.(Val345Met) and p.(Arg630Gln) variants were rare and predicted as potentially pathogenic by the in the silico algorithms used in this study. The p.(Val345Met) was not found in either the control group or in publicly available databases. This variant was identified in a female patient with severe obesity, metabolic syndrome and hyperglycemia. The p.(Arg630Gln) was also absent in our control group, but it was reported in gnomAD with an extremely low frequency. This variant was observed in a female patient with morbid obesity, metabolic syndrome, hypertension and severe binge-eating disorder., Conclusion: Our study reported for the first time two rare and potentially pathogenic variants in Brazilian patients with severe obesity. Further functional studies will be necessary to confirm and elucidate the impact of these variants on SH2B1 protein function and stability, and their impact on energetic metabolism., Level of Evidence: Level V, cross-sectional descriptive study., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Purpose: Monogenic forms of obesity are caused by single-gene variants which affect the energy homeostasis by increasing food intake and decreasing energy expenditure. Most of these variants result from disruption of the leptin-melanocortin signaling, which can cause severe early-onset obesity and hyperphagia. These mutation have been identified in genes encoding essential proteins to this pathway, including leptin (LEP), melanocortin 2 receptor accessory proteins 2 (MRAP2) and proopiomelanocortin (POMC). We aimed to investigate the prevalence of LEP, MRAP2 and POMC rare variants in severely obese adults, who developed obesity during childhood. To the best of our knowledge, this is the first study screening rare variants of these genes in patients from Brazil., Methods: A total of 122 Brazilian severely obese patients (BMI ≥ 35 kg/m 2 ) were screened for the coding regions of LEP, MRAP2 and POMC by Sanger sequencing. All patients are candidates to the bariatric surgery. Clinical characteristics were described in patients with novel and/or potentially pathogenic variants., Results: Sixteen different variants were identified in these genes, of which two were novel. Among them, one previous variant with potentially deleterious effect in MRAP2 (p.Arg125Cys) was found. In addition, two heterozygous mutations in POMC (p.Phe87Leu and p.Arg90Leu) were predicted to impair protein function. We also observed a POMC homozygous 9 bp insertion (p.Gly99_Ala100insSerSerGly) in three patients. No pathogenic variant was observed in LEP., Conclusion: Our study described for the first time the prevalence of rare potentially pathogenic MRAP2 and POMC variants in a cohort of Brazilian severely obese adults., Level of Evidence: Level V, cross-sectional descriptive study.

Purpose: The rs17782313 variant of the MC4R gene plays an important role in the obesity phenotype. Studies that evaluate environmental factors and genetic variants associated with obesity may represent a great advance in understanding the development of this disease. This work seeks to assess the association of the polymorphism of MC4R rs17782313 on plasma parameters, including leptin, ghrelin, tumor necrosis factor (TNFα) and interleukin 6 (IL6), and on the eating behaviors of morbidly obese women., Methods: 70 adult women with BMI between 40 and 60 kg/m 2 were recruited. Laboratory and anthropometric data were recorded. Using a visual analog scale (VAS), the feelings of hunger and satiety were evaluated. The presence or absence of binge eating was evaluated through the Binge Eating Scale (BES) questionnaire. Habitual food intake was analyzed using 3-day dietary records. TaqMan ® assays were conducted using real-time PCR to assess genotype polymorphism variants from peripheral blood DNA., Results: This study found that female patients with the MC4R rs17782313 polymorphism had high levels of ghrelin and reduced levels of IL6 in the postprandial period. We observed a higher prevalence of severe binge eating in more than 50% of women with at least one risk allele., Conclusion: Our hypothesis is that the MC4R rs17782313 polymorphism may influence the release of ghrelin, even without being associated with feelings of hunger and satiety. More than half of women with this polymorphism exhibited severe binge eating., Level of Evidence: Level III: case-control analytic study.