A drug similar to one that causes birth defects has won FDA approval to treat anemia in people who suffer from certain kinds of rare bone marrow disorders known as myelodysplastic syndromes, or MDS.

The Food and Drug Administration approved the drug, lenalidomide, late Tuesday. Celgene Corp., of Summit, N.J., plans to market the drug as Revlimid.

MDS refers to various disorders caused when bone marrow does not make enough normal blood cells. Patients with MDS can require blood and platelet transfusions and treatment with antibiotics for infections.

Patients treated with Revlimid in clinical trials went transfusion-free for 44 weeks on average, according to the FDA.

About 7,000 to 12,000 cases of MDS are diagnosed each year in the United States. Symptoms include weakness, fatigue, infections, bruising, bleeding and fever.

"This new product will offer a much needed treatment option for patients suffering from this rare illness that, in some cases, has been found to progress to fatal forms of leukemia," said Dr. Steven Galson, director of FDA's Center for Drug Evaluation and Research.

The drug is similar to thalidomide, known to cause birth defects.

The company must market Revlimid under a risk management plan to keep it from being used by women who may become pregnant. Female patients must undergo pregnancy testing and give informed consent before they can take the drug, which will bear a so-called "black box warning" on its label. Pharmacists and others who prescribe and dispense the drug must register with the risk management program, the FDA said.

The warning also includes the potential need to lower the common dose due to suppressed blood counts and increased risk of blood clots in patients, the FDA said. Common side effects of Revlimid include low platelet count, low white blood cell count, diarrhea, itch, rash and fatigue.

Studies in animals are ongoing to determine whether Revlimid can cause birth defects if taken during pregnancy. The FDA and Celgene will evaluate the risk management plan once results of those studies are completed, the agency said.