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Background: Endothelial dysfunction (ED), an early indicator of atherosclerosis, is a well-established predictor of cardiovascular disease. This study investigates ED in children with rare genetic variants linked to obesity and explores the prevalence of these variants in pediatric obesity. Methods: Under an IRB-approved protocol, 54 pediatric patients with severe obesity (BMI ≥ 97%) were screened using the Rhythm® Genetics Test panel between 2021 and 2024 through the Uncovering Rare Obesity® program. This clinically approved buccal test targets 79 genes and one chromosomal region. ED was measured using EndoPAT® (Itamar Medical Ltd by Zoll US based company) in 24 of these patients with related gene variants and compared to controls. Results: Genetic screening: Among the 54 patients screened, 42 (78%) had positive genetic variants, including 18 males and 24 females. The most common variants were PCNT (n = 9), BBS (n = 9), SEMA3 (n = 8), ALMS1 (n = 6), SDCCAG8 (n = 5) and MC4R (n = 5). Endothelial dysfunction: Included 21 subjects with a mean age of 12 years and a mean BMI of 33.31 kg/m². The mean RHI for patients with the PCNT variant was significantly higher (1.34, p = 0.02) compared to controls, but no significant differences were observed for other variants, including BBS, ALMS1, and SH2B1. Conclusions: In this small pilot study, no significant difference in ED was found between children with or without genetic variants, except for PCNT, which showed a higher RHI. Targeted genetic screening revealed 78% with identified pathogenic variants like MC4R, which can clinically guide therapy. Further research is needed to investigate ED in children with obesity variants. [ABSTRACT FROM AUTHOR]

Monogenic obesity, caused by mutations in one of the genes involved in the control of hunger and satiety, is a rare cause of early onset obesity (EOO). The most common of the single gene alterations affect the leptin gene (LEP), resulting in congenital leptin deficiency that manifests as intense hyperphagia, EOO and severe obesity associated with hormonal and metabolic alterations. Only eight mutations of LEP associated with congenital leptin deficiency have been described in humans to date. In this study, we report a novel, homozygous, missense mutation in exon 3 of the LEP gene (chr7:127894610;c.298G>A) resulting in the amino acid substitution of asparagine for aspartic acid at codon 100 (p.Asp100Asn) in a 10-month-old infant who presented to us with severe hyperphagia and EOO. She was subsequently found to have low serum leptin concentrations. Additionally, a homozygous missense variation of unknown significance in exon 11 of Bardet-Biedl syndrome-1 gene (chr11:66291279; G>A; Depth 168x) was detected. Significant abnormalities of lipid parameters were also present in our patient. Both parents were thin but there was a family history suggestive of EOO in a paternal uncle and a cousin. In conclusion, we report the second patient from India with a novel mutation of the LEP gene associated with severe obesity. [ABSTRACT FROM AUTHOR]

Abstract: Obesity and the metabolic syndrome represent serious health threats affecting increasing numbers of individuals, with females being more affected than males and with growing incidence among children and adolescents. In the present study, we used the OLETF rat model of early-onset obesity to examine the influence of different timing of food restriction on long-term obesity levels in females. Food restriction took place at different time windows: from weaning until postnatal day (PND) 45 (early); from weaning until PND90 (chronic); or from PND45 until PND70 (late). Follow-up continued until PND90. During and after the termination of the diet-restriction period, we focused on peripheral adiposity-related measures such as fat pad weight (brown, retroperitoneal and inguinal); inguinal adipocyte size and number; and leptin, oxytocin and glucose levels. We also examined body weight, feeding efficiency, spontaneous intake after release from diet-restriction, and plasma creatinine levels and estrous cycle characteristics as a result of the chronic diet. The results suggest that while food restriction produced significant weight and adiposity loss, OLETF females presented poor weight loss retention after the early and late short-term diets. The estrous cycle structure and time of first estrous of the OLETF rats were normalized by chronic food restriction. Females responded to early food restriction in a different manner than males did in previous studies, further emphasizing the importance of sex-appropriate approaches in the investigation and treatment of the pathologies related to obesity and the metabolic syndrome. [Copyright &y& Elsevier]

Ontogenetic trajectories from weaning to adulthood and sex differences in feeding patterns were examined in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of early onset overeating-induced obesity, and a natural cholecystokinin- I receptor knockout. Overnight patterns of licking a palatable liquid diet (Ensure) were analyzed on Postnatal Days 22, 38, 60, and 90. Because different microstructure profiles may reflect alterations in the influence of positive and negative signals, we examined meal parameters to uncover developing mechanisms underlying eating behavior in this strain. OLETF rats displayed significantly greater caloric intake, larger meals (in number of licks), and more (within-meal) clusters of feeding (which were shorter in duration and contained fewer licks per cluster) than did Long-Evans Tokushima Ohtsuka (LETO) strain controls. OLETF rats also had significantly lower satiety ratios than LETO rats. Moreover, we identified sex differences in the age of emergence of microstructural patterns of obesity-related overeating, suggesting that systems other than cholecystokinin may be disrupted, possibly worsening the OLETF strain's obesity phenotype. [ABSTRACT FROM AUTHOR]

Abstract: Studies in rodent models demonstrated that the central cannabinoid receptor (Cnr1) mediates the orexigenic effects of cannabinoids. To analyze whether genetic variation in the cannabinoid receptor gene (CNR1) is implicated in human obesity, we initially genotyped 8 single nucleotide polymorphisms (SNPs) located in the 5′ region (rs9353527, rs754387, rs6454676), intron 2 (rs806379, rs1535255), exon 3 (rs2023239), intron 3 (rs806370) and the coding region (rs1049353) in up to 364 German obesity trios (extremely obese child or adolescent and both parents). The transmission disequilibrium test (TDT) was negative for these SNPs (p >0.05). However, there was a slight trend towards preferential transmission of the A-allele of rs1049353 (p =0.12). We therefore genotyped this SNP in 235 independent German obesity families (at least two obese sibs and both parents) and in parallel screened the CNR1 coding region for sequence variations in 120 German extremely obese children and adolescents who mainly contributed to the initial trend observed for rs1049353. The trend for preferential transmission of the A-allele could not be substantiated (pedigree disequilibrium test, PDT p =0.15; A-allele less frequently transmitted). In the mutation screen we detected two rare variations, one novel non-conservative mutation (c.1256C>A; A419E) and the known variant 1419+1G>C. In addition, we confirmed the presence of rs1049353. As these variants could not explain the initial TDT, we conclude that there is no evidence for an association of CNR1 alleles with obesity in our study groups. [Copyright &y& Elsevier]