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Why It’s Important to Be Aware of This Rare Blood Disease

Dr. Chris Patriquin

Hematologist, Clinician Investigator, University Health Network & Assistant Professor of Medicine, University of Toronto

Cindy Anthony

Executive Director, AAMAC

While rare, paroxysmal nocturnal hemoglobinuria can be fatal if not treated. That’s why awareness is so important.

Zach Cressman, 20, is an aviation student living in Southwestern Ontario. One day in February 2015, at age 12, he was sent home from school after taking part in a physical education test. “I had scored half of what I usually did and my phys-ed teacher was worried,” recalls Zach.  

Zach Cressman

His family took him to the doctor, who ordered blood work. Later that evening, the family doctor called, urging Zach’s parents to take him to the hospital immediately. There, Zach received several transfusions before being sent the next day to London Health Sciences Centre (LHSC) in London, Ont., for further testing. The diagnosis was aplastic anemia (AA), an acquired bone marrow failure condition where blood cell production is significantly reduced. Zach spent a year at LHSC for treatment until his condition stabilized, returning every six months afterwards for monitoring. On one of those follow-up visits, doctors discovered that Zach had paroxysmal nocturnal hemoglobinuria (PNH)

An abnormality of blood stem cells 

PNH is an acquired genetic abnormality of the blood stem cells. “PNH occurs when a mutation develops in some of these stem cells and causes the subsequent blood cells produced to lose their protection against a part of our immune system called complement,” says Dr. Chris Patriquin, a hematologist and Clinician Investigator at the University Health Network and Assistant Professor of Medicine at the University of Toronto. 

Having information on how to manage their disease and what the latest treatments are, and someone to talk to about their concerns is very critical for these patients.

Though the median age of diagnosis is around 40, PNH can occur in people of any age, including those as young as Zach. “There’s a close association between AA and PNH, but many patients with AA have a small bone marrow clone that typically doesn’t require any treatment other than monitoring to make sure there’s no progression to full, active hemolytic PNH,” says Dr. Patriquin. This was fortunately the case with Zach. However, patients with large clone PNH run the risk of developing thrombosis and severe and potentially fatal blood clots throughout the body if not diagnosed and treated. 

Recognizing the signs and symptoms

Getting a PNH diagnosis is challenging, however, not only because it’s such a rare disease, but also because many early warning symptoms such as chronic fatigue, easy bruising and bleeding, shortness of breath (especially after exertion), and abdominal pain can be linked to other diseases. “One of the more telling symptoms is dark urine, often occurring first thing in the morning. This is reflective of the ongoing blood cell breakdown,” says Dr. Patriquin.

Diagnosis is made through a simple test on the patient’s blood called flow cytometry. “This tells us the percentage of cells circulating that are missing those protective mechanisms on the outside of the cell,” says Dr. Patriquin. “The core treatment strategy is to control the complement system with complement blockers to prevent further blood cell breakdown.”

Resources and support available

With targeted treatment, people living with PNH can live full and productive lives. And with new therapies in late-stage clinical trial development or recently approved, the prognosis is even more positive.

There are also patient supports available. One is the Aplastic Anemia and Myelodysplasia Association of Canada (AAMAC). The AAMAC supports people with bone marrow diseases, including PNH, through online support groups, print and online resources, and one-on-one peer support.  “We encourage them to reach out to us,” says Cindy Anthony, Executive Director of the AAMAC. “Having information on how to manage their disease and what the latest treatments are, and someone to talk to about their concerns is very critical for these patients.” 

Talk to your doctor if you notice the symptoms described or learn more by visiting

This article was made possible with unrestricted support from Alexion Pharma Canada.

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