GSA: Interrogating the Epigenetics of Sexual Orientation

Also at GSA's Genetics 2010: Model Organisms to Human Biology conference in Boston this week, Eric Vilain of the University of California, Los Angeles, spoke about his work interrogating the most sexually dimorphic behavioral trait in humans — sexual orientation — via methylation patterns, or what he calls "epigaynomics." He and his team recruited 34 monozygotic twin pairs discordant for sexual orientation and interrogated 28,000 CpG loci on an Illumina platform. They found the methylation profile between gay and straight individuals to be "utterly similar" — the maximum difference between twins discordant for sexual orientation was only about 4 percent. What they did find, however, were distinguishable methylation patterns with age — three genes, they determined, explain nearly 70 percent of age-related variance. Vilain said that it's possible their CpG analysis wasn't exhaustive enough to capture epigenetic variation or that their inference of environmental effects was too limited. Ultimately, their results show "no detectable significant epigenetic [patterns] between monozygotic twin pairs discordant for sexual orientation."