The X Factor

Dateline: 03/04/99

A gene imbalance may provide a critical link between ovarian cancer and the X chromosome. A gene that is prevalent in invasive ovarian cancer may influence another gene, breast carcinoma 1 (BRCA1). The mutated form of BRCA1 is known to cause inherited ovarian cancer.

In a study conducted at the University of Iowa Cancer Center by Richard Buller M.D. and others, researchers studied a sample group of 213 women. Of those who had a BRCA1 mutation, 82% also had a genetic condition called nonrandom X-chromosome inactivation. This is a condition in which one X chromosome from the mother or father is more active in all cells.

Female embryo cells each contain two X-chromosomes, one from the mother and one from the father. Early in development, one of the chromosomes in each cell usually becomes inactive. This is normally a random event such that most females are a "mosaic." Almost half of the cells end up with inactivation of the maternal X, while the other half of the cells have inactivation of the paternal X.

As this study shows, the delicate balance of maternal and paternal genes is not true of women with invasive ovarian cancer and particularly for those with the BRCA1 mutation. Of those women studied, over 50% had a preponderance of one X activated in most cells. Of those with the BRCA1 mutation, over 90% had a preponderance of one X activated. Because of this nonrandom inactivation of one X, the individuals can be more susceptible to genetic anomalies.

Based on the results of the study, scientists believe that there is a "factor" on the X chromosome that influences the expression of the BRCA1 gene. This would explain why women in the same family often develop cancer at different stages in life.

Scientists will now look for the location of the factor that interacts with BRCA1. They are hopeful that this research will lead to new ways of diagnosing, and perhaps preventing, ovarian cancer.

What do you think? How might this gene imbalance be treated? How might scientists go about finding the missing factor? Come over to the Biology Forum and share your thoughts, opinions, and feelings.

For related information, see:

• Researchers Find Possible Genetic Link Between The X Chromosome And Ovarian Cancer
  News report from Science Daily
  
  
• The Microwave Detector
  Information about a new detection method for breast cancer.
  
  
• The Cancer Stopper
  Have we finally found a cure for cancer?