Researchers found that disabling the FucM (fucose mutarotase) gene – which influences the levels of oestrogen to which the brain is exposed – caused the mice to behave as if they were male as they grew up.
The observation that FucM-/- female mouse exhibits a phenotypic similarity to a wild-type male in terms of its sexual behavior appears to be due to the neurodevelopmental changes in preoptic area of mutant brain resembling a wild-type male. Since the previous studies indicate that AFP plays a role in titrating estradiol that are required to consolidate sexual preference of female mice, we speculate that the reduced level of AFP in FucM-/- mouse, presumably resulting from the reduced fucosylation, is responsible for the male-like sexual behavior observed in the FucM knock-out mouse.
Professor Chankyu Park of the Korea Advanced Institute of Science and Technology in Daejon, South Korea, who led the research, said: “The mutant female mouse underwent a slightly altered developmental programme in the brain to resemble the male brain in terms of sexual preference.”
Scientists have long sought a genetic link to homosexuality, but the academics behind the latest study stressed that it was impossible to say whether their discovery had any relevance to human sexuality.
By deleting the enzyme-producing gene, the scientists believe that they caused the female mice to be exposed to extra oestrogen, by preventing their brains from filtering out the hormone.
While oestrogen masculinises the brain in mice, it does not have the same effect on humans.
Professor Park now hopes to investigate whether the enzyme produced by the gene – fucose mutarotase – has any influence on human sexuality, but conceded that it may be “very difficult” to find willing volunteers.