A quantitative trait locus on chromosome 22 for serum leptin levels adjusted for serum testosterone.
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.


METHODS
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.


CONCLUSIONS
Given these results, we hypothesize that a QTL on chromosome 22 may influence the level of leptin adjusted for testosterone.
Martin
Lisa J
LJ
Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA. lisa.martin@chmc.org
Mahaney
Michael C
MC
Almasy
Laura
L
Hixson
James E
JE
Cole
Shelley A
SA
MacCluer
Jean W
JW
Jaquish
Cashell E
CE
Blangero
John
J
Comuzzie
Anthony G
AG
D000328:Adult; D002892:Chromosomes, Human, Pair 22; D005260:Female; D005838:Genotype; D006630:Hispanic or Latino / Q000235:genetics; D006801:Humans; D020738:Leptin / Q000097:blood*; D008126:Lod Score; D008297:Male; D008800:Mexico / Q000208:ethnology; D008875:Middle Aged; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics*; D012727:Sex Characteristics; D013739:Testosterone / Q000097:blood*
D020738:Leptin; D013739:Testosterone