The disease is caused by a genetic deficiency in the G6PD enzyme, which makes red blood cells susceptible to breakdown and hemolysis when exposed to certain oxidative substances, such as fresh fava beans or broad beans.
What is the G6PD enzyme?
The enzyme is called glucose-6-phosphate dehydrogenase (G6PD). A deficiency in this enzyme leads to a decrease in the production of reduced glutathione, resulting in a loss of protection for red blood cells. These cells then become vulnerable to breakdown when exposed to oxidative substances like fava beans and certain medications.
Where is it prevalent?
This disease is found worldwide but is most common in Greece, Italy, the Mediterranean basin, and the Middle East. Favism is an inherited recessive disorder, meaning that the disease only manifests if both copies of the X chromosome are affected. Women have two copies of the X chromosome,
so if one is affected, the other usually compensates, which explains why females are less frequently affected. Men, however, have only one X chromosome, so if it is affected, the disease will manifest, explaining the higher prevalence in males. Affected males pass the gene to their daughters but not to their sons, while a carrier mother can pass the disease to both sons and daughters. However, women rarely develop symptoms of this disease.
Symptoms
Consuming fava beans can lead to anemia, which may be severe and life-threatening. The main clinical symptoms include paleness, headache, dizziness, nausea, vomiting, fatigue, abdominal pain, dark-colored urine, and jaundice (yellowing of the skin and mucous membranes like the conjunctiva), caused by an increase in bilirubin due to extensive red blood cell destruction.
Diagnosis:
Diagnosis is based on the patient’s medical history and physical examination, along with certain laboratory tests. Hemoglobin levels are typically low, bilirubin levels are elevated, and red blood cells appear fragmented under the microscope. A urine test may show hemoglobinuria. Confirmation is achieved by measuring the activity of the G6PD enzyme in red blood cells, which is reduced in affected individuals.
Treatment
In cases of severe red blood cell breakdown, the patient may develop acute, life-threatening anemia, requiring emergency blood transfusion under close medical supervision. Multiple transfusions may be needed, and kidney function should be monitored to prevent acute renal failure caused by severe hemolysis.
Prevention:
Prevention is key to managing this hereditary condition. As long as the patient avoids the foods and medications that trigger hemolysis, they will generally remain healthy. Educating the patient and their family (if the patient is a child) is essential. It is crucial to emphasize that this is a genetic condition and not a contagious disease.
Dr. Haider Adil Al-Obaidi
Pediatrician
