Early puberty gene discovered

Scientists in America have discovered a gene that they believe might double the chances of girls reaching puberty early, thought to be one possible reason for an increased risk of breast cancer. It was reported at the American Association for Cancer Research annual meeting in New Orleans that nearly all girls carrying a specific gene variation experienced puberty as young as nine years old.

The team of scientists found that the gene variant, called CYP1B1, causes testosterone to be broken down twice as rapidly as normal by enzymes in the liver, suggesting that the male sex hormone may be more important in the sexual development of girls than has been thought. When the study began, it was thought that a gene controlling levels of oestrogen would be responsible, but it may be that for girls who inherit the gene variation, a reduction in the level of testosterone at a critical time in their development might be the reason for early puberty.

Taking part in the study were 192 girls between the ages of nine and 10. It was found that 90 percent of the 22 girls with two copies of the variant gene were developing breasts, compared with only 40 percent of girls without the variation. Of girls with one copy of the gene variation, 56 percent experienced puberty early.

Dr Fred Kadlubar, who presented these findings at the conference said that while more research was needed it was possible that the genetic variant might be 'found to be associated with either more aggressive breast cancer or early onset of the disease'.