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Issue: 02/02/05
Researcher finds genes influencing sexual orientation
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[email article]
02/02/05
Sharon Butler
In the first study combing the entire human genome for genetic determinants of male sexual orientation, a UIC researcher has identified several areas that appear to influence whether a man is heterosexual or gay.
The study, which is available online, will be published in the March issue of the biomedical journal Human Genetics.
“There is no one ‘gay’ gene,” said Brian Mustanski, a psychologist in the department of psychiatry and lead author of the study.
Mustanski found stretches of DNA that appear to be linked to sexual orientation on three different chromosomes in the nucleus of cells of the human male.
“Sexual orientation is a complex trait, so it’s not surprising that we found several DNA regions involved in its expression,” he said.
“Our best guess is that multiple genes, potentially interacting with environmental influences, explain differences in sexual orientation.”
Working with colleagues at the National Institutes of Health, Mustanski analyzed the genomes of 456 men from 146 families with two or more gay brothers.
While earlier studies focused solely on the X chromosome, one of the two sex chromosomes, the present study also examined all 22 pairs of non-sex chromosomes. The other sex chromosome, called Y, was not explored because it is not believed to contain many genes
Identical stretches of DNA on three chromosomes — chromosomes 7, 8 and 10 — were found to be shared in about 60 percent of the gay brothers in the study, compared to about 50 percent expected by chance. The region on chromosome 10 correlated with sexual orientation only if it was inherited from the mother.
“Our study helps to establish that genes play an important role in determining whether a man is gay or heterosexual,” said Mustanski.
“The next steps will be to see if these findings can be confirmed and to identify the particular genes within these newly discovered chromosomal sequences that are linked to sexual orientation.”
Other researchers involved in the study were Dean Hamer, National Institutes of Health; Nicholas Schork and Caroline Nievergelt, University of California at San Diego; Michael DuPree, Pennsylvania State University; and Sven Bocklandt, University of California at Los Angeles.
The study was supported in part by grants from the National Science Foundation and the National Institutes of Health.
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