Thalassemia is a family of inherited blood disorders characterized by too few healthy red blood cells with adequate hemoglobin, the protein necessary to transport oxygen. “Developing red blood cells don’t make it out of the bone marrow, and patients become horribly anemic,” says John Wood, MD, PhD, principal investigator at The Saban Research Institute of Children’s Hospital Los Angeles.
Treatment typically requires a blood transfusion every three weeks or so, but each transfusion also introduces a year’s worth of iron. “Iron is hard to come by, so the body hangs on to every molecule and recycles it,” says Wood. “Thalassemia patients are getting as much as 17 years of iron each year in transfusions. It’s too much. The liver stores it until the excess eventually spills into the endocrine glands and then into the heart.”
The heart is the breaking point. Until relatively recently, medical monitoring of patients with thalassemia involved conducting occasional, painful liver biopsies to assess levels of iron in the organ. But liver biopsies tell doctors nothing about the heart, and heart biopsies are ineffective because iron deposits found there are too heterogeneous.
“You could miss them and think everything was perfectly normal,” says Wood. “By the time a patient saw a cardiologist, it was usually too late. They were likely dead in six months, no matter what we did.”
Wood, who has a doctorate in bioengineering, believed magnetic resonance imaging (MRI) of the heart was a diagnostic solution and came to Children’s Hospital Los Angeles in 2000 intent on proving it. By 2005, he had demonstrated the efficacy of noninvasive cardiac MRIs for patients with thalassemia.
Cardiac MRIs are now the standard of care for thalassemia in the United States, where the disease is relatively rare. Patients are typically scanned annually, with treatments to remove excess iron adjusted accordingly.
“Patients get a scan of their heart, liver and pancreas, which tells us a lot about where they are on the disease spectrum,” says Wood. “We’re able to stratify risk and decide how aggressively to treat.”
The bigger challenge is fighting thalassemia where the disease is endemic: in tropical regions and among people of Mediterranean, Asian and African descent. One such place is Thailand, where an estimated 37 percent of the indigenous population carries at least one defective gene for the disease, and approximately 300,000 babies are born with the disorder each year. It is a major public health dilemma, with significant adverse economic consequences.