Chronic obesity is associated with impaired bone health. However, few investigations have been conducted to assess bone physiology in early-onset obesity. In this study, we measured specific bone turn Show more
Chronic obesity is associated with impaired bone health. However, few investigations have been conducted to assess bone physiology in early-onset obesity. In this study, we measured specific bone turnover and metabolic biomarkers in children with severe obesity with biallelic loss-of-function variants of the leptin (LEP), leptin receptor (LEPR), or melanocortin 4 receptor (MC4R) genes. Thirty-nine children aged 0.3-8.8 years with a BMI SDS ≥ 3, previously identified with pathogenic variants in LEP, LEPR, or MC4R, were recruited for the current study. Additionally, 13 age-matched children with severe obesity who tested negative for variants in known obesity-related genes were included, and another 13 unrelated age-matched children with normal body weight served as the control group. Serum osteocalcin, osteopontin, osteoprotegerin, and sclerostin levels were assessed using multi-analyte profiling. Serum leptin, insulin, and cortisol levels were determined using ELISA. Serum levels of osteocalcin and osteopontin, specific markers of bone formation, were significantly lower in children with LEP and LEPR biallelic variants than in the control group. In contrast, the values of these two biomarkers in children with MC4R deficiency were significantly higher than those in the other groups. No differences were observed in the bone resorption markers osteoprotegerin and sclerostin. Hyperleptinemia was more pronounced in children with LEPR deficiency. Serum insulin concentrations were elevated in individuals with MC4R deficiency, whereas serum cortisol levels were significantly higher in children with LEP deficiency than in all other groups. Our data demonstrate that osteogenic activity (but not resorption activity) is differentially affected in children with complete genetic disruption of the leptin-signaling pathway. Children with MC4R deficiency showed higher osteogenic markers, but children with LEP and LEPR deficiencies showed the opposite. Our results support the usefulness of bone turnover biomarkers for the assessment and management of bone health in different types of obesity. Show less
The long-term clinical outcomes of severe obesity due to leptin signaling deficiency are unknown. We carry out a retrospective cross-sectional investigation of a large cohort of children with leptin ( Show more
The long-term clinical outcomes of severe obesity due to leptin signaling deficiency are unknown. We carry out a retrospective cross-sectional investigation of a large cohort of children with leptin (LEP), LEP receptor (LEPR), or melanocortin 4 receptor (MC4R) deficiency (n = 145) to evaluate the progression of the disease. The affected individuals undergo physical, clinical, and metabolic evaluations. We report a very high mortality in children with LEP (26%) or LEPR deficiency (9%), mainly due to severe pulmonary and gastrointestinal infections. In addition, 40% of surviving children with LEP or LEPR deficiency experience life-threatening episodes of lung or gastrointestinal infections. Although precision drugs are currently available for LEP and LEPR deficiencies, as yet, they are not accessible in Pakistan. An appreciation of the severe impact of LEP or LEPR deficiency on morbidity and early mortality, educational attainment, and the attendant stigmatization should spur efforts to deliver the available life-saving drugs to these children as a matter of urgency. Show less