Pyruvate Kinase Deficiency (PK)

What is pyruvate kinase deficiency?

Pyruvate kinase (PK) deficiency is a rare, genetic, lifelong condition that affects red blood cells. Symptoms can be vary greatly. How it affects one person can be significantly different from how it affects another person. In some instances, the disorder can be life-threatening at birth. Other individuals may have mild or no symptoms of the disorder and go undiagnosed into adulthood. And others may develop symptoms during childhood or as adults. The main symptom, hemolytic anemia, can be associated with fatigue or low energy.

Everyone who has PK deficiency is born with it, even if they are diagnosed later in life. To understand how PK deficiency affects your child, it's necessary to understand the role of healthy red blood cells and pyruvate kinase and what happens to red blood cells in PK deficiency.

Red blood cells have a flexible shape called a biconcave disc, which looks like a flattened sphere. This flexible shape allows the cells to squeeze through narrow blood vessels (capillaries) as they deliver oxygen to the body. Healthy red blood cells can squeeze through the smallest capillaries located in the spleen, a filtering organ in the abdomen.

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Ongoing PK deficiency research is helping to identify potential treatments to keep this 2-year-old healthy and thriving.

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Closeup of Scarlette, who has pyruvate kinase deficiency, wearing a pink hat and looking up

The role of pyruvate kinase

Red blood cells make energy by converting glucose, a sugar, into pyruvate, an important molecule in metabolism, and a high-energy molecule called adenosine triphosphate (ATP) in a multistep process called glycolysis. Pyruvate kinase is an enzyme that makes the last step in this process happen. It converts a protein called phosphoenolpyruvate into pyruvate and ATP. Less pyruvate kinase results in less ATP, so red blood cells have less energy and begin to break down.

When red blood cells breakdown

The breakdown of red blood cells is called hemolysis. Normally, after 120 days, red blood cells break down and are removed from the circulation by the spleen. Red blood cells that do not have enough pyruvate kinase cannot make enough energy to hold their shape, and they break apart more easily than healthy red blood cells. Instead of lasting 120 days, PK-deficient red blood cells only last a few days to weeks.

How common is PK deficiency?

PK deficiency is rare, estimated to occur in three to eight per 1,000,000 people. It is equally common in men and women. People with PK deficiency are from all over the world. Although most mutations are rare, some specific amino acid changes are found more commonly in particular populations, such as the Amish community, the Romany population and in some Mediterranean countries.

How we care for PK deficiency

The Blood Disorders Center at Dana-Farber/Boston Children's Cancer and Blood Disorders Center provides comprehensive diagnostic, treatment, and preventive services for a wide range of blood disorders. Your child will receive care from some of the world’s most experienced hematologists with extensive expertise in caring for children with PK deficiency.