FRIDAY, Aug. 26 (HealthDay News) -- Scientists report an advance in the genetics of uterine fibroids, the most common noncancerous tumors in women of childbearing age.

Uterine fibroids, which can cause abnormal bleeding, abdominal pain and discomfort, occur in 60 percent of women by the age 45. Fibroids are also a major cause of infertility and the most common reason for hysterectomy.

Despite their importance, little has been known about what causes these tumors to develop.

In this study, researchers at the University of Helsinki in Finland examined the genetics of 18 fibroid tumors and found that as many as 70 percent of them had specific mutations in a gene called MED12.

The gene produces the MED12 protein, which is known to play a role in regulation of general "gene transcription." The researchers said the pattern of mutations identified in this study suggests that MED12's function is disrupted in a specific way in most fibroid tumors.

The finding that so many fibroid tumors have these specific mutations suggests that it may be possible to develop targeted therapies, but that's likely to take a long time, the study authors said.

"This is a giant step towards understanding why fibroids arise, but towards design of targeted therapies it is a very early step. Let's hope that this journey has begun," research team leader Lauri Aaltonen said in a university news release.

The study was published in the Aug. 25 online edition of the journal Science.

More information

The U.S. National Institute of Child Health and Human Development has more about uterine fibroids.