Genetic mutations resulting in delayed puberty are focus of study.

2003 DEC 4 - (NewsRx.com & NewsRx.net) -- Identifying genetic mutations that delay puberty in a small number of children may also lead to better infertility treatment and birth control, says a Medical College of Georgia physician-scientist.

"Irreversible, delayed puberty is fortunately rare," said Dr. Lawrence C. Layman, chief of the MCG Section of Reproductive Endocrinology, Infertility and Genetics. "But if we can find mutations in genes in these patients, that shows the genes are important for normal puberty so they could be useful in infertility treatment as well. You also could block them and make a contraceptive. So there are a lot of possibilities."

Layman recently received a $1 million grant from the U.S. National Institutes of Health, the second NIH grant he has to tackle the laborious task of studying approximately 100 genes believed to have a role in puberty and reproduction. He'll look at the numerous potential mutations of each and find whether they cause idiopathic hypogonadotropic hypogonadism, an unfortunate series of genetic circumstances that forestall the sex steroids or hormones that transform children into reproductive adults.

Boys usually begin puberty by age 10 or 11 and girls by age 8 or 9, when the hypothalamus in the brain begins releasing gonadotropin-releasing hormone, which stimulates the pituitary gland to make follicle-stimulating hormone, FSH, and luteinizing hormone, LH. FSH and LH, in turn, prompt the ovaries to produce estrogen and eggs and the testes to produce testosterone and sperm.

"When patients present to us with delayed puberty, it usually means they are not making either estrogen or testosterone," said Layman. "And, if you then measure the levels of FSH and LH, and they are low, that means the problem is in the brain, either the hypothalamus or the pituitary."

These adolescents receive hormone replacement therapy throughout their reproductive lives. If they decide to have children, they will need comparatively expensive gonadotropin (FSH and LH) injections to stimulate ovulation in women and sperm production in men.

Mutations of nine genes have been found that contribute to about 20% of the cases of delayed puberty. Layman's studies have contributed to identification of two of these mutations, including those on the GNRH receptor and FSHB, but the total list of contributors could be in the hundreds, he said.