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A quantitative trait locus on chromosome 22 for serum leptin levels adjusted for serum testosterone
Lisa J Martin1, Michael C Mahaney, Laura Almasy
1Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. lisa.martin@chmc.org
Objective:
Studies have reported the existence of marked sexual dimorphism in serum leptin levels in humans with women having approximately two to three times the levels of men. We have shown that this sexual dimorphism has a strong genetic component arising from a genotype by sex interaction, but adjusting leptin levels for testosterone eliminates this interaction. Because interactions such as genotype x sex can confound the detection of quantitative trait loci (QTLs), we wanted to determine if there are QTLs associated with the expression of leptin adjusted for testosterone.
Research Methods And Procedures:
We performed a genome-wide scan using multipoint linkage analysis and implemented a general pedigree-based variance-component approach to identify genes with measurable effects on variation in leptin levels independent of testosterone in 318 Mexican Americans from the San Antonio Family Heart Study.
Results:
We detected significant evidence of linkage (log of the odds ratio = 3.44) for a QTL on chromosome 22.
Discussion:
Given these results, we hypothesize that a QTL on chromosome 22 may influence the level of leptin adjusted for testosterone.