You’ve probably never heard of PNH; only one or two people in a million are diagnosed with it each year. Still, the illness is as devastating as it is rare.
The disease has its roots in the body’s complement system, a group of proteins that helps the immune system eliminate infectious microorganisms. When bacteria enter the human body, the complement system serves as the first line of defense. It creates proteins on the outer walls of invading cells that cause the invading cells to pop like balloons.
Normally, our red blood cells are immune to the proteins created by the complement system. But in PNH, which results from a genetic mutation, abnormal bone marrow cells make red blood cells that are susceptible to harm by the complement system. So when the complement system launches an attack, that same barrage bursts the red blood cells in PNH patients, spilling hemoglobin into the blood stream. This hemoglobin can also leak into the urinary tract, and the disease get its name because in these recurring (paroxysmal) episodes, the abnormal presence of blood (hemoglobinuria) is most notable in the dark-colored urine that has accumulated in the bladder during the night (nocturnal).
This loss of hemoglobin is the culprit behind many of the hallmark symptoms of PNH.
“Hemoglobin is the protein in red blood cells that carries oxygen to the tissues,” says Dr. Stephen Prescott, OMRF’s president and a vascular biologist. “When it’s lost, that causes anemia, which manifests itself in symptoms like fatigue, weakness and shortness of breath.” People with PNH are more prone to infections due to a deficiency of white blood cells, and they are also at greater risk of developing leukemias—cancers in blood-forming cells. “With PNH, you’ll also see abnormal platelet function, and that causes problems in the blood clotting process.”
The result can be deadly: Thromboses—blood clots—are the leading cause of death among PNH patients. The disease also can cause potentially fatal hemorrhaging. And unlike many illnesses, there is no predictable course to PNH.
“With this disease, there’s no peace of mind. The worst could happen at any time,” says Prescott. “PNH is like a ticking time bomb.”
Following a round of blood work, doctors at first told Sandy Roark she was suffering from idiopathic thrombocytopenic purpura, or ITP. The condition is characterized by a low platelet count and often—as in Roark’s case—by spontaneous bruising. But when she failed to respond to steroids, the standard initial course of treatment for ITP, Roark’s physicians sent her to a specialist for a bone marrow biopsy. That biopsy led to her diagnosis with PNH.