Ronald Jerro

Ronald Jerro, who has MDS,has his blood drawn by oncology lab technician Antoinette Chappell-Williamson at Johns Hopkins Hospital. (Kenneth K. Lam, Baltimore Sun / July 6, 2012)

The underlying medical condition that contributed to the death of writer and filmmaker Nora Ephron and is forcing ABC news anchor Robin Roberts to get a bone marrow transplant is a rare and complicated disease that scientists are still trying to figure out.

Both women were afflicted with myelodysplastic syndrome, a group of disorders caused when the body produces damaged blood cells. Abnormal cells can eventually outnumber good cells, leaving people with low blood cell counts and needing transfusions and other treatments.

Ephron, 71, suffered from a more serious form of the disease, which manifested into acute myeloid leukemia, a fast-forming cancer of the bone marrow cells. Her doctor told The New York Times that the disease left her unable to fight off a case of pneumonia.

Only 12,000 to 15,000 new cases of MDS are diagnosed each year, and scientists and doctors don't know exactly what causes the syndrome in most patients. It is more common in older people with the average diagnosis at age 71. White men are most likely to develop MDS.

The disease is hard to study because it shows up in people in so many variations. It can afflict one or more of the three blood cells — red, white and platelets. Treatment can vary by patient.

"In most cases we can't identify a reason why people get it," said Dr. B. Douglas Smith, an associate professor of oncology at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Hospital. "There are many different levels of the syndrome, so it isn't all the same."

In about 10 percent of cases, doctors know that MDS is caused by chemotherapy or radiation treatment for cancer. Roberts, who hosts "Good Morning America," told viewers earlier this summer that her disease was likely caused by breast cancer treatment she underwent five years ago.

Some heavy metals such as lead and mercury and chemicals such as benzene have been associated with the syndrome.

Many patients don't know much about the disease until they are diagnosed. Diagnosis is hard because symptoms such as fatigue and shortness of breath may be confused with age-related issues.

Anna Marie Sebring was diagnosed earlier this year after when she collapsed while walking through the kitchen of her Sparks home.

Sebring, 74, was taken to the hospital, where a battery of tests pointed to MDS. She said she now lives a fairly normal life with medication. She gets injections of decitabine for five days then takes off 28 days before getting another round of the medication. The drug changes the chemical composition of DNA in bone marrow cells in order to help restore normal blood cell production. Sebring also receives blood transfusions when her blood cell counts get low.

"I never expected to feel this good [with the disease]," said Sebring, who is being treated at University of Maryland Medical Center. "Even when I get the treatments I don't feel ill or anything."

Most patients with MDS receive this kind of treatment, called "supportive care," to help manage the disease and prevent bleeding and infections.

Ronald E. Jerro of Great Falls, Va., was diagnosed with MDS in 2010 after feeling unusually tired after walking up three flights of stairs.

"Every level I started puffing worse, and I could barely breathe," he said.

Jerro, now 75, passed a stress test with no problem. His blood pressure, liver and kidney function and other vitals also were better than normal for his age. But more extensive blood tests found that Jerro had extremely low levels of platelets and red and white blood cells.

Jerro gets injections of the drug Vidaza, which aids the body in making healthy cells. Being treated at Johns Hopkins Hospital, Jerro said he has had to get more frequent transfusions recently because his blood counts have been dropping more rapidly. He is entering a drug trial in coming weeks to try a new drug.

Roberts, 51, will receive a bone marrow transplant, which will destroy bad cells and replace abnormal bone marrow stem cells with healthy donated cells from her sister. But not all patients can get a transplant, which is considered the most effective means to prolong life. The risks associated with a transplant are high for the older population that generally gets MDS.

Maria Baer, director of hematologic malignancies at the University of Maryland Marlene and Stewart Greenebaum Cancer Center, said that treatment for MDS has gotten better in the last decade and more clinical trials are under way. About 25 percent of cases turn into the leukemia from which Ephron suffered, she said.