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Favism; deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD).


Overview:
Favism disease is a genetic metabolic abnormality caused by deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD).
Which leads to hereditary disease involving an allergic-like reaction to favabean (Vicia faba). This disease may develop a hemolytic anemia (blood disorder) by eating the beans, or even by passing through a field where the plants are in flower.
Favism disease is inherited as it’s a sex-linked trait and occurs due to glucose-6-phosphate dehydrogenase deficiency .This disease is distributed in Mediterranean countries (Spaniards, Greeks, Italians , Armenians, and Jews).
Favism is one of the most common forms of enzyme deficiency disease and is believed to affect more than 500 million people worldwide. Although the distribution is high, the most majority of people remain clinically asymptomatic throughout their lives. There are some researches which state that the disorder is more common in males, but this is not accurate.

Causes:
The main reason for Favism is deficiency in glucose-6-phosphate dehydrogenase (G6PD) enzyme which is an X-linked genetic trait. G6PD deficiency is caused by alterations (mutations) in the G6PD gene, and it maps to the X chromosome. However, not all families who have G6PD-deficient have  risk for favism. The defective gene is sex-linked, transmitted from mother who is usually a healthy carrier to her son or daughter.
G6PD  enzyme is essential for assuring a normal life span for red blood cells as this enzyme is required for the proper function of red blood cells, and for oxidizing processes. So its deficiency leads to hemolytic anemia and  rupture of RBCs with jaundice following the intake of fava beans, certain legumes and various drugs .

Symptoms:
Common symptoms of a hemolytic anemia include:
- Sudden rise of body temperature.
- Change color of skin and mucous membrane to yellow color.
- Dark yellow-orange urine.
- Fatigue, Pallor, general deterioration of physical conditions.
- Fast breathing and heavy.
- Weak, rapid pulse.
- Jaundice.
- Enlarged spleen (splenomegaly).
As mentioned before , favism is characterized by anemia due to the premature destructions of red blood cells (hemolytic anemia), as a result to anemia , there are several disorders occur include:

Diagnosis
A diagnosis is based upon the identification of some symptoms and characteristic physical findings, and thorough clinical evaluation, knowing a patient history, and doing some specialized tests. If a person experiences some symptoms, and spontaneously reports eating fava beans and lives or come from an area where a G6PD deficiency is common, suspicion of the disorder should be high.
If doctors think that the person has favism, they request a variety of blood tests to confirm a diagnosis and rule out other conditions that cause similar conditions.
The diagnosis depends on demonstrating deficiency of the G6PD enzyme through either a quantitative assay or a screening test such as fluorescent spot test.
In addition to Molecular genetic test which can detect mutations in the specific gene responsible for G6PD deficiency, but is available only as diagnostic service at specialized laboratories.

Treatment:
Most affected people don’t need treatment. G6PD deficiency (Favism) is often managed by preventative measures. Individuals should be diagnosed for the G6PD defect before being treated with certain drugs such as antimalarials ,certain antibiotics, and other medications known to trigger hemolysis in G6PD-deficient individuals. In individuals with favism disease, should avoid fava beans or known drugs which enhance favism .
As mentioned before In individuals with favism disease shouldn’t take certain medication which enhance favism, so those drugs should be discontinued under a physician’s supervision. If an infection cause favism (enhance it) , appropriate steps should be taken to treat the infection.
Some adult people may need short-term treatment with fluids to prevent hemodynamic shock which is inadequate supply of blood to the organs ,or in severe cases where the rate of hemolysis (rupture of red blood cells) is very rapid, even blood transfusions. We should take care during blood transfusions if the person suffers from favism.
In Neonatal babies who suffer from jaundice as a symptom to favism, are treated by placing them under special lights (bili lights) that alleviate the jaundice. In more severe cases, we have to do exchange transfusion. Which means to replace the affected infant’s blood with fresh donor blood or plasma.
Genetic counseling may be useful for patients and their families.


Favism; deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD). Reviewed by Tpdsm on October 05, 2017 Rating: 5

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