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Glucose phosphate isomerase deficiency
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Glucose phosphate isomerase deficiency

Glucose phosphate isomerase deficiency is a rare inherited disorder that causes chronic hemolytic anemia, leading to the premature breakdown of red blood cells and, in some cases, neurological difficulties.

Overview

Glucose phosphate isomerase (GPI) deficiency is an inherited disorder that affects red blood cells, which carry oxygen to the body's tissues. People with this disorder have a condition known as chronic hemolytic anemia, in which red blood cells are broken down (undergo hemolysis) prematurely, resulting in a shortage of red blood cells.

Symptoms

Chronic hemolytic anemia can lead to several symptoms, including:

  • Unusually pale skin (pallor)
  • Yellowing of the eyes and skin (jaundice)
  • Extreme tiredness (fatigue)
  • Shortness of breath (dyspnea)
  • A rapid heart rate (tachycardia)
  • An enlarged spleen (splenomegaly)
  • An excess of iron in the blood
  • Small pebble-like deposits in the gallbladder or bile ducts (gallstones)

Hemolytic anemia in GPI deficiency can range from mild to severe. In the most severe cases, affected individuals do not survive to birth. Individuals with milder disease can survive into adulthood. People with any level of severity of the disorder can have episodes of more severe hemolysis, called hemolytic crises, which can be triggered by bacterial or viral infections.

A small percentage of individuals with GPI deficiency also have neurological problems, including intellectual disability and difficulty with coordinating movements (ataxia).

Frequency

GPI deficiency is a rare cause of hemolytic anemia; its prevalence is unknown. About 50 cases have been described in the medical literature.

Causes

GPI deficiency is caused by mutations in the GPI gene, which provides instructions for making an enzyme called glucose phosphate isomerase (GPI). This enzyme has two distinct functions based on its structure:

  • When two GPI molecules form a complex (a homodimer), the enzyme plays a role in a critical energy-producing process known as glycolysis (also called the glycolytic pathway). During glycolysis, the simple sugar glucose is broken down to produce energy. Specifically, GPI is involved in the second step of the glycolytic pathway, converting a molecule called glucose-6-phosphate to another molecule called fructose-6-phosphate.
  • When GPI remains a single molecule (a monomer), it is involved in the development and maintenance of nerve cells. In this context, it is often known as neuroleukin (NLK).

Some GPI gene mutations may result in a less stable homodimer, impairing the activity of the enzyme in the glycolytic pathway. The resulting imbalance of molecules involved in the glycolytic pathway eventually impairs the ability of red blood cells to maintain their structure, leading to hemolysis.

Other GPI gene mutations may cause the monomer to break down more easily, thereby interfering with its function in nerve cells. In addition, the shortage of monomers hinders homodimer formation, which impairs the glycolytic pathway. These mutations have been identified in individuals with GPI deficiency who have both hemolytic anemia and neurological problems.

Inheritance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

  • Glucose-6-phosphate isomerase deficiency
  • Glucosephosphate isomerase deficiency
  • GPI deficiency
  • Nonspherocytic hemolytic anemia due to glucose phosphate isomerase deficiency

Frequently Asked Questions

Individuals with mild GPI deficiency can often lead normal lives, but they require regular monitoring of hemoglobin levels and iron studies. Because chronic hemolysis leads to increased iron absorption, patients are at risk for iron overload, which can damage the heart and liver. Dietary restrictions usually do not include avoiding iron-rich foods, but rather avoiding unnecessary iron supplements. Clinicians may prescribe iron chelation therapy if blood iron levels become dangerously high, and patients should maintain a balanced diet rich in folate to support red blood cell production.
small percentage of individuals with GPI deficiency develop neurological problems, including intellectual disability and ataxia (difficulty coordinating movements). These symptoms are thought to result from the enzyme's role in brain development and function. Diagnosis involves genetic testing for mutations in the GPI gene and neurological evaluation. Management is supportive and may include physical therapy, occupational therapy, and educational interventions to address motor and cognitive challenges. There is no specific cure for the neurological aspects, so early intervention is key to maximizing quality of life.
While all three conditions cause chronic hemolytic anemia, GPI deficiency is distinct because it is an autosomal recessive disorder affecting a glycolytic enzyme, whereas G6PD deficiency is X-linked and often episodic. Unlike hereditary spherocytosis, where splenectomy is a common curative option, splenectomy in GPI deficiency is generally not recommended as a primary treatment because it does not stop the underlying enzymatic defect and increases the risk of severe infections. Management typically focuses on folic acid supplementation, monitoring for iron overload, and treating crises as they occur.
Common triggers for hemolytic crises in GPI deficiency include bacterial or viral infections, certain medications, and physical stress. Patients should seek immediate medical attention if they experience a sudden worsening of fatigue, dark or tea-colored urine, rapid heart rate, or increased jaundice (yellowing of the skin and eyes), as these indicate acute red blood cell breakdown that may require hospitalization for transfusions or other supportive care.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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