Identified: Genetic Markers for Testosterone and Estrogen Regulation
Research has identified genetic markers that not only influence a protein involved in regulating oestrogen and testosterone levels in the bloodstream, but reveal its' close proximity to genes controlling liver function, fat and carbohydrate metabolism and type 2 diabetes
The work was led by the Peninsula College of Medicine and Dentistry, University of Exeter, and Boston University School of Medicine, in collaboration with a global consortium. Their results are published online in PLoS Genetics.
Some of the genetic markers for this protein are also near genes related to liver function, metabolism and type 2 diabetes, demonstrating an important genetic connection between the metabolic and reproductive systems in men and women.
Sex hormone binding globulin (SHBG) is the key protein that carries testosterone and oestrogen in the bloodstream in both men and women. As the main carrier of these sex hormones, SHBG helps to regulate their effects in different tissues and organs in the body.
In addition to effects on reproduction in men and women
through regulation of sex hormones,
SHBG has been linked to many chronic diseases
including type 2 diabetes and
hormone-sensitive cancers such as breast and prostate.
Previous family studies have demonstrated that approximately 50 per cent of the variation in SHBG concentrations in the bloodstream is inherited from parents, suggesting that SHBG levels are under significant genetic control. However, little has been known about the specific genes that influence SHBG levels.
Investigators examined human genomes from 21,791 men and women to determine which genes influence SHBG levels and validated the results from this genome-wide association study (GWAS) in an additional 7,046 men and women.
They identified 12 single-nucleotide polymorphisms (SNPs), or DNA sequence variations, associated with the concentration of SHBG circulating in the bloodstream. Although these genetic variants only explain a small fraction of the sex hormone variability seen between individuals, they could provide insight into the diseases connected to sex hormone regulation.
The results showed that the SNPs that influence SHBG levels are near genes related to liver function, fat and carbohydrate metabolism and type 2 diabetes. In addition, there were genes that had stronger effects in one sex compared to the other.
"These findings highlight the diverse range of
biological processes that may be impacted
by sex hormone regulation,"
Dr. John Perry
Peninsula College of Medicine and Dentistry
University of Exeter
The study was carried out in collaboration with the Framingham Heart Study and investigators from 15 international epidemiologic studies participating in the Cohorts for Heart and Aging Research in Genetic Epidemiology (CHARGE) consortium.
Original article: http://www.eurekalert.org/pub_releases/2012-07/tpco-gmf072012.php