G6PD Deficiency (Favism)
Glucose 6-phosphate dehydrogenase (G6PD) deficiency is an inherited abnormality that affects the red blood cells. In this condition, an enzyme known as G6PD, located in the red cells, functions at a reduced level. This can cause the red cells to break up under certain conditions, most commonly, after exposure to certain drugs. The resulting anaemia is known as haemolytic anaemia.
Who gets G6PD deficiency?
It is most common in people of southern Italian extraction, African, Chinese, Southeast Asian or Mediterranean ethnic origin. Among Kurdish Jews, 50% of males have the disorder.
How is G6PD inherited?
The gene determining the structure of G6PD is carried on the X chromosome, so inheritance is sex-liked. This means that the deficiency can be passed on from mother to son, but not father to son. Women do not usually suffer from G6PD deficiency because they have two X chromosomes, so have one ‘normal’ gene to balance the one for G6PD. This referred to as carrier status.
What are the symptoms of G6PD deficiency?
Most G6PD deficient people never suffer any clinical symptoms until something causes a haemolytic episode. They may suffer dizziness, headache, vomiting and fever, and a blood test may reveal haemolytic anaemia.
What causes haemolytic episodes?
Certain drugs are known to cause haemolysis in people with G6PD. These include sulphonamides, certain analgesics, and some antimalarials. Eating broad beans can also cause haemolysis, hence the alternative name, favism, after vicia fava, the botanical name for broad beans.
What is the treatment for G6PD deficiency?
There is no treatment, but G6PD deficiency does not cause any problems unless there is exposure to an agent that causes haemolysis. The best treatment, therefore, is prevention. Do not take any medicines without consulting your doctor and avoid broad beans and the plant itself. Always tell health professionals if you have G6PD deficiency, so they can prescribe drugs that are safe.
Rarely, the haemolytic anaemia is severe enough to require blood transfusion.