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Int J Mol Epidemiol Genet 2013;4(2):86-100

Original Article
The methylation of the LEPR/LEPROT genotype at the promoter and body
regions influence concentrations of leptin in girls and BMI at age 18 years if
their mother smoked during pregnancy

Mitra Yousefi, Wilfried Karmaus, Hongmei Zhang, Susan Ewart, Hasan Arshad, John W Holloway

Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC,
USA; Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis,
Memphis, USA; College of Veterinary Medicine, Michigan State University, East Lansing, MI, 48824, USA; The David Hide
Asthma and Allergy Research Centre, St Mary’s Hospital, Newport, Isle of Wight, UK; Clinical & Experimental Sciences, and
Human Development & Health, Faculty of Medicine, University of South-ampton, Southampton, UK

Received May 8, 2013; Accepted June 15, 2013; Epub June 25, 2013; Published June 30, 2013

Abstract: To determine whether DNA methylation (DNA-M) of the leptin receptor genotype (LEPR/LEPROT) links gestational
smoking and leptin serum levels and BMI later in life, we focused on female offspring, 18 years of age, from the Isle of Wight
Birth Cohort (IOWBC). Leptin binds to the leptin receptor encoded by the LEPR/LEPROT genotype. Using general linear
models, we tested a two-stage model. First, we investigated whether single nucleotide polymorphisms (SNPs) acting as
methylation quantitative trait loci (methQTLs) depending on gestational smoking were related to differentially methylated
cytosine-phosphate-guanine (CpG) sites. In stage 2, we tested whether the selected CpG sites, in interaction with other SNPs
(modifiable genetic variants, modGV), are associated with serum leptin and BMI (stage 2). Children from the IOWBC were
followed from birth to age 18. Information on gestational smoking was gathered upon delivery. SNPs tagging LEPR and
LEPROT genes were genotyped. Data on LEPR/LEPROT DNA-M and leptin were obtained from blood samples drawn at age
18; to determine BMI, height and weight were ascertained. Blood samples were provided by 238 girls. Of the 21 CpG sites,
interactions between gestational smoking and SNPs were detected for 16 CpGs. Methylation of seven of the 16 CpGs were, in
interaction with modGVs, associated with leptin levels at age 18 years. Two CpGs survived a multiple testing penalty and were
also associated with BMI. This two-stage model may explain why maternal smoking has a long-term effect on leptin levels and
BMI in girls at age 18 years. (IJMEG1305003).

Keywords: LEPR, LEPROT, leptin, CpG sites, in utero smoking exposure, rs12059300, BMI

Address correspondence to: Dr. Wilfried Karmaus, Division of Epidemiology, Biostatistics, and Environmental Health, School
of Public Health, University of Memphis, 301 Robison Hall, Memphis, TN 38152, USA. Phone: 901-678-2491; Fax: 901-678-
0372; E-mail: Karmaus1@memphis.edu