Favism occurs due to a defect in the G6PD gene, which codes for an important enzyme in the human body. The enzyme deficiency leads to anemia and hemolysis and cannot be treated causally. The prognosis is very good if affected individuals avoid triggering substances for life.
What is favism?
Favism is the pathological course of an enzyme deficiency. Affected individuals have a mutation in the G6PD gene, resulting in a deficiency of glucose-6-phosphate dehydrogenase in the body. The consequences are anemia, an insufficient concentration of hemoglobin in the blood, and recurrent hemolysis, in which the erythrocytes are destroyed. Overall, slightly less than 8 percent of all people have mutations in the G6PD gene; however, the onset of favism occurs in only 25 percent of them. People with this gene mutation who have already developed symptoms should avoid any contact with substances that are dangerous to them. This includes, for example, beans of the species Vicia faba and their pollen. Favism occurs mainly in the Mediterranean region, parts of Africa, the Middle East, and some Asian countries such as Thailand or India. Surprisingly, there is no outbreak of malaria in people affected by favism, since the malaria pathogens can hardly multiply due to the lack of enzymes.
Causes
Favism is a hereditary disease, which is inherited in an X-linked recessive manner. Because inheritance is X-linked, females are affected much less often than males. Women can compensate for a genetic defect on one X chromosome by the other. Men have only one X chromosome, which is why a mutation on a gene located there cannot be compensated. The mutation in the G6PD gene is predominant in ethnic groups living in the area where the malaria pathogen is distributed. Glucose-6-phosphate dehydrogenase plays an important role in human metabolism. A deficiency leads to reactive chemical compounds, namely peroxides, being able to attack components of the red blood cells unhindered. This results in chronic anemia and hemolysis. In principle, the symptoms only set in when those affected come into contact with triggering substances. These substances are found in field beans (Vicia faba), currants and peas, among others. The disease can also be triggered by various other substances such as acetylsalicylic acid or antimalarial drugs. Stress and infections can also be triggers for favism.
Symptoms, complaints, and signs
Symptoms and complaints typically appear some time after contact with triggering substances. The first signs are usually noticeable after a few hours. However, several days may pass before symptoms appear. Not everyone with a G6PD gene defect automatically develops favism. Why the disease breaks out in some people affected by the mutation and not in others is currently not fully understood. Favism is not infrequently accompanied by severe and potentially life-threatening symptoms. Initial signs of an episode include abdominal pain and backache, fever, chills, and a general feeling of weakness. In severe hemolytic anemia, patients are usually in a life-threatening state of shock. If the course is severe, an episode can lead to acute kidney failure.
Diagnosis
As part of the diagnostic process, a detailed medical history is first taken. During this process, the treating physician asks about the use of medications and contact with triggering foods such as field beans. In order to make a definitive diagnosis, the physician draws blood, which is examined in the laboratory. In the case of G6PDH deficiency, a reduced enzyme activity is detected. To prevent the test results from being falsified, the enzyme activity in the reticulocytes, the precursors of the red blood cells, is examined. It is also useful to have the number of reticulocytes determined. The course of the disease is mild in most cases as long as triggering substances are avoided. However, if affected individuals are unaware of their disease, severe enzyme deficiency may result, significantly reducing life expectancy.
Complications
As a rule, no complications occur with favism if the patient completely avoids contact with the substance or substances in question. This can limit daily life and living, reducing quality of life.In many cases, favism is difficult to detect because the symptoms do not appear until several days after contact with the triggering substance. Favism can be avoided if this substance is avoided. The affected person suffers mainly from severe pain in the abdomen, lower abdomen and back. There is also fever and chills, which is why the symptoms of favism are often mistaken for a cold or flu. In addition, there is a feeling of weakness, dizziness and often vomiting. However, the patient also experiences a state of shock, which can distinguish favism from influenza. If favism is not treated directly, it can damage the kidney. In many cases, no treatment is possible. The patient must abstain from certain ingredients for the rest of his or her life. This does not reduce life expectancy. Severe relapses are treated in the intensive care unit and do not lead to further symptoms if treated quickly and early. Due to the lack of hygiene and medical care in the countries where favism occurs preferentially, this can cause severe complications.
When should you go to the doctor?
Favism cannot be treated directly and causally. Therefore, those affected do not always need to see a doctor. Above all, the symptoms can be completely avoided by avoiding the triggering substances. A doctor should be consulted if the complaints cause an acute emergency. This is the case, for example, if the affected person suffers from high fever and severe pain in the abdomen or back. A general feeling of weakness and fatigue may also indicate the disease and should definitely be investigated. Furthermore, the disease can also lead to a state of shock. If the patient loses consciousness due to the symptoms, an emergency doctor must be called directly or the hospital must be selected. In most cases, the disease can be diagnosed by a general practitioner or directly in the hospital. Since there is no causal treatment for the disease, patients must avoid the triggering substance throughout their lives. In most cases, the patient’s life expectancy is not negatively affected by the disease.
Treatment and therapy
To date, there is no treatment for favism that eliminates the underlying cause. The gene mutation exists from the moment of fertilization and cannot be treated. People affected by favism must avoid all contact with the disease-causing substances for the rest of their lives. This applies to foods such as beans and peas as well as to certain medications. If this is successful, life expectancy is not shortened compared to the unaffected population. Favism is particularly problematic if the disease remains undiagnosed for a long time and contact with a triggering substance then occurs. This leads to a severe episode, which requires intensive medical treatment. Due to the severe hemolytic anemia that can accompany favism, there is a risk of severe complications. In individual cases, haptoglobin is used for therapy. This is a protein found in blood plasma that is involved in the transport of hemoglobin. In hemolysis, the level of haptoglobin in the blood is reduced. This treatment is not suitable for all patients and is used only in emergencies.
Outlook and prognosis
Because favism is a genetic disease, it is not considered curable at the current status. With current medical and especially legal guidelines, no change can be made in human genetics. Nevertheless, not all carriers of the gene mutation experience the onset of symptoms of enzyme deficiency. Patients who show symptoms have a good prognosis under certain conditions. With adherence to medical guidelines, there is the prospect of lifelong freedom from symptoms. The health impairments of enzyme deficiency are triggered in affected patients as soon as they ingest selected substances through their food intake. Permanent abstinence from the triggering nutrients leads to recovery. If consumption of the affected substances occurs later in life, symptoms immediately set in. Nevertheless, a spontaneous healing occurs as soon as the substances are removed from the organism. In exceptional cases, irreversible damage to the organism occurs when the substances are ingested.In an acute condition due to the enzyme deficiency, acute renal failure|failure of renal function may occur. In these cases, the patient requires transplantation of a donor kidney to have a chance of recovery. Otherwise, lifelong medical dialysis treatment is necessary or premature death occurs.
Prevention
The genetic defect, which is the cause of favism, cannot be prevented because it exists before birth. To prevent episodes of the disease, affected individuals must take strict care not to come into contact with triggering substances such as field beans. When treating bacterial or viral infections, the physician must be informed about the enzyme deficiency, because some medications contain substances that are dangerous for affected persons. For example, medications containing sulfonamides or acetylsalicylic acid should not be taken.
Follow-up
In most cases of favism, the affected person has no or only a few measures and options for aftercare. The affected person is primarily dependent on early detection and subsequent treatment of the disease to prevent further complications. Only early detection of favism can prevent further symptoms. An independent cure cannot occur in this case. Since favism is a genetic disease, it can also be inherited. Therefore, if a person wishes to have children, genetic counseling should also be performed to possibly prevent this. In case of this disease, the affected person should avoid contact with the triggering substances in any case. It should be clarified by a doctor which substances are involved. Furthermore, the affected persons are very often dependent on the help of acquaintances and friends or also the family in their everyday life, in order to facilitate this. Talks are also useful to prevent psychological upsets or depression that could result from the favism. Whether there is a reduced life expectancy due to the disease cannot be universally predicted. Contact with others affected by this disease may also be useful.
Here’s what you can do yourself
In an acute hemolytic crisis, self-help measures are not enough. It must be treated medically without delay. The underlying enzyme defect cannot be cured. However, affected individuals can prevent its consequences – anemia and acute episodes – by avoiding the triggering substances and products. These include beans, especially the broad bean plant and its pollen, as well as peas, soy products and currants. Many medications can also trigger hemolysis in people with G6PD deficiency, including common painkillers such as acetylsalicylic acid (ASA), as well as certain antibiotics (e.g., sulfonamides and ciprofloxacin) and antimalarial drugs such as chloroquine. Therefore, patients should inform their physician about their enzyme defect so that he or she does not prescribe any of these preparations. Henna products, mothballs and toilet deodorants often contain naphthalene. This is another substance that can lead to a hemolytic crisis. Infections can also critically increase oxidative stress. That is why it is essential to treat them early to prevent an episode. Patients prone to severe crises should carry an emergency identification card. In chronic hemolysis, daily administration of a folic acid supplement alleviates anemia. Because G6PD deficiency is hereditary, affected individuals should also have their children tested for the defect.
