PNH is a rare, chronic blood disease that causes below-normal levels of hemoglobin, a proteinproteinsLarge, complex molecules that play many important roles in the body and can be thought of as the “workhorses” of cells. Proteins are required for the structure, function and regulation of the body’s organs and tissues. in red blood cellsred blood cellsThe most common type of blood cell. Their job is to carry oxygen using an important molecule, hemoglobin, around the body. that is responsible for moving oxygen around the body.

PNH is caused by a genetic mutation. This change in the body’s DNA causes red blood cellsred blood cellsThe most common type of blood cell. Their job is to carry oxygen using an important molecule, hemoglobin, around the body. to be produced without key proteinsproteinsLarge, complex molecules that play many important roles in the body and can be thought of as the “workhorses” of cells. Proteins are required for the structure, function and regulation of the body’s organs and tissues. needed to protect them from the body’s immune systemimmune systemA sophisticated defense network used to protect the body from dangers like disease and infection.. Without this shield, the immune system attacks them. You may hear your doctor refer to this process as “uncontrolled complement activation.”

Hemolysis refers to the “breaking apart” of red blood cells. It occurs when the immune system attacks these cells as though they were dangerous viruses or bacteria. When red blood cells break open, hemoglobin is released. Hemolysis causes many of the symptoms of PNH. Consistently low hemoglobin may also indicate ongoing hemolysis.

PNH symptoms vary from person to person. In some individuals they can be mild, in others more severe. Potential symptoms include:

• FatiguefatigueA feeling of being overtired or exhausted, with low energy and a desire to sleep, which interferes with normal daily activities. Fatigue is one of the most common symptoms of PNH.
• Difficulty breathing
• Bruising or bleeding easily
• Small red dots on the skin
• Severe headache
• Blood clots
• Blood in urine

PNH can be diagnosed through a wide range of blood tests. One of the most common methods is flow cytometryflow cytometryThe most common method of testing for PNH, this test confirms whether red blood cells are missing their protective shield. It also calculates the percentage of blood cells impacted by PNH, which is referred to as your clone size. A large clone size means you have a high percentage of blood cells that can be attacked by the complement system, which may lead to more severe symptoms., which can determine if there are proteinsproteinsLarge, complex molecules that play many important roles in the body and can be thought of as the “workhorses” of cells. Proteins are required for the structure, function and regulation of the body’s organs and tissues. missing from the surface of blood cells.

Approximately 400-500 people are diagnosed with PNH in the United States every year. There may be as many as 5,000-6,000 people in the U.S. who have PNH.

PNH can impact people of any age, gender or race. Most often, people are diagnosed during their 30s.

The only known risk factor for PNH is aplastic anemia, a rare disease that occurs when a person’s bone marrowbone marrowThe soft fatty tissue inside certain bones that houses stem cells, some of which will ultimately become blood cells. Bone marrow provides the nutrients and environment needed for blood cells to be created. Once these cells are fully mature and ready to go to work, they leave the bone marrow and enter the bloodstream. does not make enough new blood cells. Some scientists believe that aplastic anemiaaplastic anemiaA rare blood disease that is a known risk factor for PNH. Aplastic anemia occurs when a person’s bone marrow does not make enough new blood cells. Some scientists believe that aplastic anemia weakens the body’s bone marrow, which then affects its ability to produce healthy red blood cells. People with PNH can share symptoms with those that have aplastic anemia, such as low blood cell counts. weakens the body’s bone marrow, which then affects its ability to produce healthy red blood cells.

PNH is not cancer. PNH is a rare blood disease. Blood cells originate in bone marrow. Other diseases involving bone marrow can be cancer (e.g., leukemia), but PNH is not one of them. Doctors who specialize in treating PNH often also treat people with cancer or work at centers that focus on treating people with cancer, but PNH should not be confused with cancer.

PNH is not always life-threatening. Since the introduction of PNH treatments more than a decade ago, most people with PNH who do not develop additional complications have a relatively normal life expectancy. However, people can still be at risk for the development of blood clots or other disorders that might affect life expectancy.

The Aplastic Anemia and MDS International Foundation (AAMDS) offers support finding and connecting with specialists here.

There are a variety of FDA-approved treatments that address PNH and its symptoms. Some people have had success with a bone marrow transplant or hematopoietic stem cell transplant, which replaces unhealthy stem cells with healthy ones. Either of these procedures may cure their PNH. There are also treatments that can help prevent red blood cells from being destroyed.

Learn more about various treatment options here. Talk to your doctor to see if a potential treatment is right for you.

There are two types of hemolysis, intravascular (IVH)Intravascular hemolysisThe destruction of red blood cells inside a blood vessel. and extravascular (EVH)Extravascular hemolysisDestruction of red blood cells that occurs in the liver or spleen., both of which cause the symptoms of PNH. Ongoing hemolysis means that red blood cells are still being destroyed even while on treatment. If you suspect your PNH symptoms may be caused by ongoing hemolysis, talk to your doctor.

There are two types of hemolysis, intravascular (IVH)Intravascular hemolysisThe destruction of red blood cells inside a blood vessel. and extravascular (EVH)Extravascular hemolysisDestruction of red blood cells that occurs in the liver or spleen., both of which may be responsible for ongoing PNH symptoms. The science behind the complement system and ongoing hemolysis may explain why these ongoing PNH symptoms can occur even with treatment. Since hemolysis begins in the complement system with a protein called C3, treatments that work farther down the cascade may not completely improve PNH symptoms.

You may be able to have children. Women who are pregnant and have PNH have a higher risk of blood clots. If you are planning a family, you should speak with your doctor to determine if it’s safe. If you and your doctor decide a pregnancy is safe for you, you can work together to develop a plan to help prevent complications and minimize risk. This may include additional treatments.

PNH is not inherited and can’t be passed on to others. PNH is “acquired,” which means the genetic mutations responsible for the disease happen during your life. You are not born with them, and you cannot pass them on to others.

The daily reality of PNH is different for everyone. Some individuals have mild symptoms, while others have more severe symptoms. One of the most common experiences is fatigue that can impact how you spend time with others, complete daily tasks and pursue work-related activities.

Everyone’s experience with fatigue is different. Fatigue is often the most debilitating symptom impacting daily life and can feel worse than any lab test result might suggest. However, everyone’s experience is unique, and the same person can have different symptoms at different times. While some have symptoms that are mild and manageable, others may have symptoms that are more severe.

Absolutely. You can see how your symptoms are impacting your overall wellness with this tool.

Your doctor is part of your care team, so speaking openly and honestly with them can help you both find the right path forward. There are a variety tools to help you with this, including identifying how PNH symptoms are affecting your life, hearing what others in the community have done, and preparing for your doctor’s appointment.

Connecting with and hearing from others who understand what it’s like to live with PNH can make a big difference. Check out stories from the PNH community here and join the conversation on Facebook and Instagram. AAMDSIF is another resource that hosts local events and a Peer Support Network.

Your healthcare provider is always the best place to turn for information about your condition and how best to treat it. A full list of additional supportive resources can be found here.