The Genetics Behind Shrimp Allergy

What is Shrimp Allergy?

Shrimp allergy is a common type of shellfish allergy that can cause a range of symptoms from mild to severe. It is an immune system reaction triggered by proteins found in shrimp, leading to symptoms like hives, swelling, difficulty breathing, and in severe cases, anaphylaxis (a severe, life-threatening allergic reaction).

Shrimp allergy is one of the most common types of shellfish allergy which affects around 3% of adults and over 1% of children in the U.S., People with shrimp allergy may also react to other crustaceans like crab and lobster, but some can tolerate mollusks like clams and oysters. The major allergen in shrimp is the tropomyosin protein which is also found in other shellfish. Tropomyosin is also common in arthropods, like house dust mites and cockroaches.

Typically, shrimp allergy is lifelong, with only about 46% of individuals outgrowing their shrimp allergy over a span of 10 years.

Diagnosis involves taking a detailed medical history, conducting skin prick tests, immunoglobulin E (IgE) blood tests, and potentially oral food challenges. Effective management of shrimp allergy involves avoiding shrimp or any crustaceans and carrying an emergency over-the-counter antihistamine or epinephrine in an auto-injector (EpiPen) form for severe allergic reactions.

Symptoms of Shrimp Allergy

The key symptoms of shrimp allergy include:

Hives, itchy or irritated skin
Nasal congestion or stuffiness
Swelling of the lips, face, tongue, throat, or other body parts
Wheezing, trouble breathing, coughing, or a tight feeling in the throat
Abdominal symptoms like diarrhea, nausea, or vomiting
Dizziness, lightheadedness, or fainting

In severe cases, shrimp allergy can also trigger anaphylaxis, a life-threatening reaction that involves multiple body systems. Symptoms of anaphylaxis include:

Swollen throat or tongue making it difficult to breathe
Shock with a severe drop in blood pressure and rapid/weak pulse
Severe skin rash, hives, or swelling
Nausea, vomiting, or diarrhea

Prompt treatment with epinephrine is crucial for managing anaphylaxis from a shrimp allergy. Seeking immediate emergency care is essential if anaphylaxis symptoms develop.

How Genetics May Influence Shrimp Allergy

Genetics can influence shrimp allergy in several ways. Genome-wide association studies (GWAS) have identified specific loci associated with shrimp allergy, especially in the histocompatibility complex, HLA-DR/DQ gene region on chromosome 6p, such as SNPs rs12175332 and rs9271608.

In the 2018 study, several genetic variants associated with shrimp allergy were found within the large genomic HLA region that includes six HLA class II genes: HLA-DQA1, HLA-DQA2, HLA-DQB1, HLA-DRB1, HLA-DRB5, and HLA-DRA. Many of these variants overlap with potential regulatory elements, such as promoter marks and enhancers, which can influence gene expression. One of the HLA-DRB1 variants, SNP rs2760995, was identified as an expression quantitative trait locus (eQTL) for the harboring gene in the HaploReg database, and 18 other SNPs were found to be associated with the expression of four other HLA genes (HLA-DQA1, HLA-DQA2, HLA-DQB2, and HLA-DRA) in both the GTExPortal and HGVD databases.

Among these, HLA-DQA2 showed the strongest association, with numerous SNPs significantly linked to its expression, suggesting that genetic variations in this region may play a crucial role in regulating nearby gene expression, and how the immune system responds to shrimp allergens. This means that certain genetic variants can influence how these HLA genes are regulated and expressed, which in turn affects the body’s immune response to the shrimp proteins. Cross-reactions between tropomyosins, a major shrimp allergen, and tropomyosins in other crustaceans are common, thus genetic factors likely influence the immune system’s ability to recognize and react to these pan-allergens.

Non-Genetic Factors Influencing Shrimp Allergy

Aside from genetics, several factors contribute to the development and manifestation of shrimp allergy:

Environmental Exposures: Exposure to environmental allergens, such as dust mites, cockroaches, and mold, can increase the risk of developing shrimp allergy.
Dietary Habits: Consuming shrimp and other seafood regularly can increase the likelihood of developing an allergy to these foods.
Cross-Sensitization: Cross-reactivity between shrimp and other arthropods, such as mites and insects, as well as vertebrates and plants, is common.
Immunocompromised Conditions: Certain conditions like alcoholic liver disease, hepatitis B or C, and male gender can increase the risk of developing shrimp hypersensitivity.
Age: Sensitization to shrimp allergens tends to decrease with age, with children showing greater epitope recognition for shrimp allergens compared to adults.
Geographical Location: The prevalence of shellfish allergy can vary significantly across different regions, influenced by local dietary habits and food availability.
Food Preparation and Consumption: The way shrimp is prepared and consumed can also impact the risk of developing an allergy. For example, consuming shrimp cephalothorax (containing brain, heart, stomach, and bladder) in East and Southeast Asia may contribute to diversified sensitization profiles compared to Western populations.

These factors, combined with genetic predisposition, contribute to the complex interplay of factors influencing the development and manifestation of shrimp allergy.

Living With Shrimp Allergy

To avoid a harmful reaction caused by shrimp allergy, several precautions can be taken based on the information provided in the sources:

Avoid Shrimp and Other Shellfish: The most effective way to prevent a shrimp allergy reaction is to avoid consuming shrimp and other kinds of shellfish.
Be Cautious with Ingredients: Shellfish, including shrimp, can be used in various food products like surimi and fish sauce. It’s important to carefully read food labels and be aware of potential hidden sources with traces of shellfish.
Consult with Healthcare Providers: If you suspect a shrimp allergy, seek advice from a board-certified allergist for proper diagnosis and to get guidance on the food items that are safe to consume and which ones are to be avoided.
Undergo Allergy Testing: If you suspect a shrimp allergy, consider getting tested by an allergist to confirm the allergy and receive professional guidance on managing the condition
Carry Epinephrine: Individuals with a known shrimp allergy should always carry an antihistamine (loratadine, cetirizine, etc.) or an epinephrine auto-injector (EpiPen) and know how to use it in the case of a severe allergic reaction, especially if you have previous experience of anaphylaxis.
Seek Immediate Medical Care: In case of severe allergic reactions or anaphylaxis, seek emergency medical care promptly, even after using epinephrine. This is a life-threatening case that requires immediate medical attention.
Stay Informed: Educate yourself about shellfish allergies, understand the symptoms, and be prepared to respond appropriately in case of an allergic reaction.

By following these measures, individuals can effectively manage and reduce the risk of experiencing adverse reactions to shrimp and other kinds of shellfish.

About the LifeDNA Nutrition Report

If you suspect you might have a shrimp allergy or want to understand your potential genetic predisposition to various nutritional and allergenic factors, getting the LifeDNA Nutrition Report is a wise decision.

This comprehensive report offers valuable insights into how your genetics can influence your reaction to certain foods, including shrimp and shellfish. By analyzing your DNA, the LifeDNA Nutrition Report provides personalized recommendations and identifies potential risks, allowing you to make informed decisions about your diet and lifestyle.

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Summary

Shrimp allergy is a common type of shellfish allergy that can cause mild to severe symptoms, triggered by proteins found in shrimp.
Symptoms of shrimp allergy include hives, swelling, difficulty breathing, and in severe cases, anaphylaxis.
Around 3% of adults and over 1% of children in the U.S. are affected by shellfish allergy, making it one of the most common allergies.
Shrimp allergy may also lead to reactions to other crustaceans like crab and lobster, but some individuals can tolerate mollusks like clams and oysters.
Typically, shrimp allergy is lifelong, with only about 46% of individuals outgrowing it over a span of 10 years.
Diagnosis involves a detailed medical history, skin prick tests, immunoglobulin E (IgE) blood tests, and potentially oral food challenges.
Genetic factors, particularly variations in HLA genes, play a significant role in shrimp allergy development and response to allergens in general.
Several non-genetic factors, including environmental exposures, dietary habits, and geographical location, can also contribute to shrimp allergy.
Management strategies include avoiding shrimp and shellfish, being cautious with food ingredients, undergoing allergy testing, carrying over-the-counter antihistamines or epinephrine, seeking immediate medical care, and being well-informed about shellfish allergies.
The LifeDNA Nutrition Report provides valuable insights into genetic predispositions, including the Potential for Shrimp Allergy trait, empowering individuals to make informed decisions about their diet and lifestyle.

References

*Understanding your genetics can offer valuable insights into your well-being, but it is not deterministic. Your traits can be influenced by the complex interplay involving nature, lifestyle, family history, and others.

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