Spring has arrived in full force! It’s time to clean up the lawnmower. Many people experience watery eyes, runny noses, and itching as the smell of freshly cut grass fills the air.
Speaking of smelling the grass… Did you know that some people can’t smell the odor of freshly-cut grass? A genetic variant (not covered by 23andMe data) prevents some people from experiencing that wonderful summertime smell.
Grass Allergies and Genetics:
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Allergies are often due to a mix of genetic susceptibility and exposure to certain triggering molecules. Several different gene variants have ties to an increased risk of grass pollen allergies.
Allergies occur when the immune system overreacts to an allergen, such as seasonal pollen. This hypersensitive immune reaction causes the release of proinflammatory cytokines. T cells are activated, producing IgE, which activates mast cells. Mast cells then degranulate, releasing histamine and other inflammatory molecules. Histamine causes a runny nose, watery eyes, and itchiness associated with allergies.[ref]
A study found an upregulation of MC1R in the noses of people with grass pollen allergies.[ref] If that gene sounds familiar, it is the same gene that codes for the melanin receptor, in which variants cause red hair.
Grass Allergy Genotype Report
Human leukocyte antigens (HLA) are part of our immune system and help the body recognize foreign invaders. People have many different variants of these genes, giving rise to protection against different pathogens. Different HLA types lead to an increased ability to fight off diseases and increased susceptibility to autoimmune diseases and allergies.
Check your genetic data for rs7775228 (23andMe v4, v5):
- C/C: more likely to be allergic to grass pollen (OR=1.33)[ref]
- C/T: slightly more likely to be allergic to grass pollen
- T/T: typical (most common genotype)
Members: Your genotype for rs7775228 is —.
Filaggrin, a protein encoded by the FLG gene, increases epithelial integrity. It is vital to keep the skin (and nose) cells tightly together so that allergens can’t cross the barrier.[ref] Variants that decrease filaggrin have ties to different types of allergies, including pollen allergies and contact dermatitis.
Check your genetic data for rs61816761 R501X (23andMe v4, v5):
- A/A: (rare) more likely to be allergic to grass pollen[ref]
- A/G: more likely to be allergic to grass pollen
- G/G: typical (most common genotype)
Members: Your genotype for rs61816761 is —.
Interleukin 2 (IL2) is involved in the body’s immune system response to foreign invaders. It is a cytokine produced by Th1 cells when stimulated by, in this case, an allergen.
Check your genetic data for rs2069762 -330T/G (23andMe v4, v5):
- A/A: typical (most common genotype)
- A/C: normal risk of grass allergy
- C/C: 2.6x increased risk of grass allergy[ref]
Members: Your genotype for rs2069762 is —.
Interleukin 33 is involved in the body’s immune system response, also. IL-33 drives the production of Th2 cytokines, acting on mast cells (among others). It is thought to be responsible for itching sensations from allergies.[ref]
Check your genetic data for rs928413 (23andMe v4, v5):
- A/A: typical
- A/G: increased risk of hay fever, allergy
- G/G: increased risk of hay fever[ref]
Members: Your genotype for rs928413 is —.
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