Think back to the drastic changes with which your body was assaulted when you hit puberty. Now, try to imagine the same set of changes happening when you were 8 years old.
Such is the plight of children who experience precocious puberty — a condition in which their bodies begin to mature years too early.
Now, for the first time, researchers have found a gene mutation that could be responsible for a small number of these cases.
"This is the first known genetic cause of precocious puberty," says lead study author Dr. Ursula Kaiser, chief of the division of endocrinology, diabetes and hypertension at Brigham and Women's Hospital in Boston, Ma. "It points additionally to the role of genetics in the timing of puberty."
The finding will be published in the upcoming issue of the New England Journal of Medicine.
Kaiser says that the gene in question was first identified a few years ago as having a role in reproductive health. In these cases, however, a flawed version of the gene was found not in those who underwent early puberty, but instead in patients who failed to go through puberty altogether.
To learn more, Kaiser collaborated with a research group in Brazil, comparing the DNA of about 53 girls who had gone through early puberty to 150 normal female subjects who had not gone through early puberty.
The mutant gene was only found in one 8-year-old girl who had gone through early puberty — and none of the normal women. The researchers believe the mutant gene led to an early surge of the sex hormone estrogen, which subsequently set the chain of events associated with puberty into motion.
Kaiser says this suggests that the gene may well act as a genetic "switch" for puberty — though she and endocrinologists not involved with the research agree that the mutation itself is not a common cause of the condition.
"This particular gene, at least, does not appear to be a common cause of precocious puberty," says Dr. Mark Groshek of the departments of pediatrics with Kaiser Permanente Colorado. "It opens a door, though, to suggest it may be possible to find other genes that explain precocious puberty in other children.
"Identifying a genetic link to any form of precocious puberty is useful, because it demonstrates that in at least some cases, there is a genetic cause."
Doctors generally define precocious puberty as the development of secondary sex characteristics — such as the growth of pubic hair, development of breasts in girls and lowering of voice in boys — before age 8 for girls and age 9 for boys.
The condition is not common, and for reasons still not entirely understood it occurs more often in girls than in boys.
And in most cases, the underlying causes of precocious puberty remain a mystery, though certain hormone disorders and brain tumors have been known to bring the condition about.
Fortunately, the condition is treatable. Treatment usually involves once-a-month injections to halt the puberty process until the child is older. Halting the treatments allows puberty to continue as normal.
But the psychological toll of the condition can be significant, and its young sufferers often require counseling to cope with the effects of being more sexually developed than their friends.
Some endocrinologists fear that recent research shows a steady decrease in the age that children — specifically girls — are hitting puberty.