Introduction
The adverse immune response of the body to food proteins is called food allergies. The mechanism of food allergies and the role of genes in its mechanism is a complex process. The studies emphasize the understanding of genes and food allergies, which helps in a more detailed view of the important pathways of the disease. Food allergies are caused due to genes. Although multiple factors cause food allergy, there is an interplay between environmental triggers and genetic susceptibility. This article discusses the contribution of genes in the mechanism of food allergies. Many food allergies are caused by genetic factors and are carried onto children by their parents (inherited). According to studies, many diseases of food allergies are caused by a single gene (monogenic).
What Is Food Allergy?
The adverse immune response of the body to ingested food proteins mediated by food-specific IgE and mast cells is called food allergy. The symptoms of a food allergy range from urticaria (an allergy that causes itching and dryness of the skin) to anaphylaxis (an acute allergy reaction in which the body becomes hypersensitive), which is life-threatening. In the last 20 years, the incidence of food allergy has risen dramatically in developed countries such as the United States of America (USA). Approximately six to eight percent of children are estimated to be affected by food allergies. The mechanism of food allergy depends upon prenatal and postnatal environmental factors related to lifestyle, diet, and other exposures. It can also be caused by genetics.
What Causes Food Allergy?
Although food allergies is caused by environmental factors and other factors, there are some genes responsible for causing food allergies:
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Major Histocompatibility Complex (MHC) - Twin studies found that the MHC complex is associated with peanut allergy. A significant allergy to apples is found to be associated with the MHC complex as well.
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CD14 Gene - CD14 gene is associated with food allergies that are receptors of lipopolysaccharides. According to studies, 175 asthmatic and 77 food-allergic patients were associated with CD14 genes.
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Fox P3 Gene - The forkhead box p3 (Fox p3) gene is associated with the best marker of regulatory cells T-cells. T-cells are a type of white blood cells in our body that fight against diseases.
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SPINK5 Gene - SPINK5 refers to serine protease inhibitor Karzal type 5. It is a protease inhibitor protein. It is expressed in the thymus (an organ in our body) and causes increased IgE levels responsible for food allergy.
How Is Food Allergy Related To Genetics?
There are several twin studies that show genes are related to food allergy.
The following are the conclusion from the studies:
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The twin studies show 14 monozygotic (single gene) twin pairs and 44 dizygotic (pair of the gene) twin pairs showed a higher concordance for peanut allergy (defined by clinical history and positive skin prick test (SPT) or peanut-specific IgE) among monozygotic (64.3 percent) compared to dizygotic (6.8 percent) twins, with a heritability estimate for peanut allergy of 81.6 percent.
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Another twin study shows sensitization to other food allergens.
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Concordance rates for sensitization were much higher in monozygotic than in dizygotic twins.
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The question of whether a food allergy in an index child predicts greater risk for siblings or links to atopy in other family members has been looked into in several studies.
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In a population-based HealthNuts study carried out in Australia, researchers first determined the overall incidence of food allergies validated by an oral meal challenge before examining links between baby food allergies and a family history of allergic disease.
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The result is that the children who met the current definition of “high-risk” (a child who has an allergic family history is at high-risk) for allergic disease showed only a modest increase in dietary allergy.
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Having two or more members of one's family that are allergic was more strongly predictive of food allergy in the child.
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The specific food associations were found with individuals with a maternal history of eczema and asthma and a sibling history of allergic rhinitis.
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Both predicted egg allergy in infants, and maternal and paternal history of asthma with allergic rhinitis predicted peanut allergy in infants.
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There were lower rates of reported allergy among parents born in East Asia but higher rates of food allergy among their infants, suggesting that environment plays an important role in the phenotypic (characteristics) expression of food allergy.
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Another study based on the clinical history and IgE level found 581 families to be food allergic.
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There are specific IgE to sesame, peanut, wheat, milk, egg white, soy, walnut, shrimp, and cod fish.
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There were also positive associations among family members (father-offspring, mother-offspring, index-other siblings) for total and specific IgE.
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The estimated heritability of food-specific IgE ranged from 0.15 to 0.35. However, a recent large-scale study of 1120 children reported that among siblings of children with food allergies, 33.4 percent had no sensitization or clinical reactivity to food. 53 percent had positive serum-specific IgE or skin prick test but no clinical reactivity to food.
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Only 13.6 percent were both sensitized and clinically reactive to food, which is only a slightly higher rate than the risk in the general population.
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Therefore, it is concluded that food allergy in a child is not determined by only family history, but environmental factors and clinical features also help to detect the cause of food allergy.
Conclusion
The study of genetics is crucial in understanding how food allergies develop. It is crucial to remember that heredity only accounts for a small portion of food allergies. Environmental factors, such as early life exposure to allergic foods and the general diversity of a person's diet, are also quite important. Genetic testing can be used to identify people with a higher risk of developing food allergies or to identify the particular allergens to which they are most susceptible.
Additionally, this knowledge aids medical practitioners in developing specialized management regimens, which may include preventative measures and prospective immunotherapies. Important consequences of genetic research include discovering particular genes linked to food allergies, identifying hereditary patterns, and creating individualized ways to diagnose and treat. Therefore, genetics has significantly improved our understanding of food allergies.
