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Case Reports in Pediatrics
Volume 2016 (2016), Article ID 6123150, 6 pages
http://dx.doi.org/10.1155/2016/6123150
Case Report

Melanocortin-4 Receptor Deficiency Phenotype with an Interstitial 18q Deletion: A Case Report of Severe Childhood Obesity and Tall Stature

1School of Medicine, Queen’s University, Kingston, ON, Canada
2Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
3Department of Pediatrics, Kingston General Hospital, Kingston, ON, Canada
4Department of Pathology and Laboratory Medicine, IWK Health Centre, Halifax, NS, Canada
5Department of Pathology, Dalhousie University, Halifax, NS, Canada

Received 30 June 2016; Accepted 28 August 2016

Academic Editor: Nur Arslan

Copyright © 2016 Sarah Abdullah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Childhood obesity is a growing health concern, associated with significant physical and psychological morbidity. Childhood obesity is known to have a strong genetic component, with mutations in the melanocortin-4 receptor (MC4R) gene being the most common monogenetic cause of obesity. Over 166 different MC4R mutations have been identified in persons with hyperphagia, severe childhood obesity, and increased linear growth. However, it is unclear whether the MC4-R deficiency phenotype is due to haploinsufficiency or dominant-negative effects by the mutant receptor. We report the case of a four-and-a-half-year-old boy with an interstitial deletion involving the long arm of chromosome 18 (46,XY,del(18)(q21.32q22.1)) encompassing the MC4R gene. This patient presented with tall stature and hyperphagia within his first 18 months of life leading to significant obesity. This case supports haploinsufficiency of MC4-R as it describes a MC4-R deficiency phenotype in a patient heterozygous for a full MC4R gene deletion. The intact functional allele with MC4-R haploinsufficiency has the potential to favor a therapeutic response to gastric surgery. Currently, small molecule MC4-R agonists are under development for pharmacologic therapy.