1. Novel Melanocortin-3 and -4 Receptor Functional Variants in Asian Children With Severe Obesity.
- Author
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Siong Gim Ong, Dehghan, Roghayeh, Dorajoo, Rajkumar, Jian-Jun Liu, Sng, Andrew Anjian, Yung Seng Lee, and Qin Ooi, Delicia Shu
- Subjects
MELANOCORTIN receptors ,ASIAN children ,CHILDHOOD obesity - Abstract
Context: Genetic variants in melanocortin 3 receptor (MC3R) and melanocortin 4 receptor (MC4R) genes are strongly associated with childhood obesity. Objective: This study aims to identify and functionally characterize MC3R and MC4R variants in an Asian cohort of children with severe earlyonset obesity. Methods: Whole-exome sequencing was performed to screen for MC3R and MC4R coding variants in 488 Asian children with severe earlyonset obesity (body mass index for age ≥97
th percentile). Functionality of the identified variants were determined via measurement of intracellular cyclic adenosine monophosphate (cAMP) concentrations and luciferase activity. Results: Four MC3R and 2 MC4R heterozygous nonsynonymous rare variants were detected. There were 3 novel variants: MC3R c.151G > C (p.Val51Leu), MC4R c.127C > A (p.Gln43Lys), and MC4R c.272T > G (p.Met91Arg), and 3 previously reported variants: MC3R c.127G > A (p.Glu43Lys), MC3R c.97G > A (p.Ala33Thr), and MC3R c.437T > A (p.Ile146Asn). Both MC3R c.127G > A (p.Glu43Lys) and MC4R c.272T > G (p.Met91Arg) variants demonstrated defective downstream cAMP signaling activity. The MC4R c.127C > A (p.Gln43Lys) variant showed reduced cAMP signaling activity at low substrate concentration but the signaling activity was restored at high substrate concentration. The MC3R c.151G > C (p.Val51Leu) variant did not show a significant reduction in cAMP signaling activity compared to wild-type (WT) MC3R. Coexpression studies of the WT and variant MC3R/MC4R showed that the heterozygous variants did not exhibit dominant negative effect. Conclusion: Our functional assays demonstrated that MC3R c.127G > A (p.Glu43Lys) and MC4R c.272T > G (p.Met91Arg) variants might predispose individuals to early-onset obesity, and further studies are needed to establish the causative effect of these variants in the pathogenesis of obesity. [ABSTRACT FROM AUTHOR]- Published
- 2024
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