rs33940208
Variant in the HTR3A gene (5-Hydroxytryptamine Receptor 3A)
rs33940208 is a single nucleotide polymorphism (SNP) in the HTR3A gene, involved in serotonin / ligand-gated ion channel. Variants at this position have been studied in relation to immune function, metabolism, and chronic illness.
This page is for educational and informational purposes only. Not a diagnostic tool. Always consult a qualified healthcare provider.
What is the rs33940208 variant?
rs33940208 is a SNP (single nucleotide polymorphism) in the HTR3A (5-Hydroxytryptamine Receptor 3A) gene. It belongs to the Neurotransmitter category and is part of the Histamine & MCAS biological cluster. HTR3A encodes the 5-HT3A subunit of the 5-HT3 receptor, a ligand-gated ion channel mediating fast serotonin signaling in the gut-brain axis.
Biological role and pathway
This variant sits within the HTR3A gene, which is involved in the serotonin / ligand-gated ion channel pathway. Genes within the Histamine & MCAS cluster work together to maintain balanced function across interconnected biological systems.
Variants in genes within this pathway may influence an individual's predisposition to altered function — particularly under conditions of physiological stress such as viral infection or prolonged illness.
rs33940208 and Long COVID / ME-CFS research
5-HT3 receptors mediate nausea, GI motility, and visceral pain; variants may affect GI symptoms and nausea in Long COVID, particularly gut-brain axis dysfunction.
This information is based on published research and does not constitute medical advice. See references below.
Parent gene: HTR3A
rs33940208 is one of 2 known variants in the HTR3A gene. To understand the full biological context of this variant, explore the parent gene page.
View HTR3A gene page →Conditions studied in relation to rs33940208
Research into HTR3A variants including rs33940208 has explored associations with the following conditions. These are areas of scientific investigation and do not imply causation.
Genetic insights from DNA data
Consumer DNA files from 23andMe, AncestryDNA, and MyHeritage contain raw SNP data. When you upload your file to ChronicDNA, the analysis engine checks your genotype against a curated panel of 80+ genes selected for their relevance to Long COVID, ME/CFS, and connected biological pathways - some of which may include HTR3A and the rs33940208 variant.
The report is educational - it explains which variants you carry, what the research says about them, and how they fit into the biological pathways most relevant to chronic illness. Results are presented in plain English with appropriate scientific context, no medical jargon, no scare tactics. All results should be discussed with a qualified healthcare provider.
Other variants in the HTR3A gene
The following variants in HTR3A are also studied in relation to chronic illness and may be analysed together for a more complete picture.
Frequently asked questions
What is the rs33940208 variant in the HTR3A gene?
rs33940208 is a single nucleotide polymorphism (SNP) located in the HTR3A (5-Hydroxytryptamine Receptor 3A) gene, which is involved in serotonin / ligand-gated ion channel. HTR3A encodes the 5-HT3A subunit of the 5-HT3 receptor, a ligand-gated ion channel mediating fast serotonin signaling in the gut-brain axis.
How may the rs33940208 variant relate to Long COVID or ME/CFS?
5-HT3 receptors mediate nausea, GI motility, and visceral pain; variants may affect GI symptoms and nausea in Long COVID, particularly gut-brain axis dysfunction.
Can a consumer DNA test detect the rs33940208 variant?
Many consumer DNA tests such as 23andMe, AncestryDNA, and MyHeritage genotype common SNPs. ChronicDNA analyses your raw DNA file and reports on variants studied in relation to chronic illness, immune function, and metabolism. This is not a diagnostic service — results are informational and educational only.
Find out if you carry the rs33940208 variant
Upload your DNA data from 23andMe, AncestryDNA, or MyHeritage and receive a personalised report covering >80 genes relevant to Long COVID and ME/CFS.
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References
The following publications were used in compiling the research context for HTR3A and its variants. This is not an exhaustive literature review.
- [1]PMID: 33664986
- [2]Nature Genetics
- [3]Gastroenterology