Thirty cubic centimeters of blood will be collected from 40 women who have a clinical history consistent with a defective maternal effect gene. DNA from these blood cells will be examined and stored. Some of the blood cells will be treated so that they can be frozen and grown in the laboratory to produce more DNA in the future. If certain mutations are not found, that means that the prevalence of such mutations is less than 10 percent, and investigators may initiate another study with 100 women. If a common mutation is found in at least four patients, the investigators will seek to collect DNA from 150 normal fertile control women for comparison.