{"gene":{"symbol":"COMT","name":"Catechol-O-methyltransferase","protein":"Catechol-O-methyltransferase","ncbi_gene_id":"1312","locus":"22q11.21","summary":"COMT encodes the enzyme that methylates and inactivates catecholamines (dopamine, epinephrine and norepinephrine) and is the main route for clearing dopamine in the prefrontal cortex. The Val158Met variant (rs4680), sometimes called the warrior/worrier SNP, changes enzyme activity roughly four-fold between genotypes. The biology is real, but the popular-science framing is oversimplified and the effects on behaviour are small.","function":"COMT methylates and inactivates catecholamine neurotransmitters: dopamine, epinephrine and norepinephrine. In most of the brain dopamine is cleared primarily by the dopamine transporter (DAT), but the prefrontal cortex has very low DAT expression and relies disproportionately on COMT to terminate dopamine signalling, so COMT activity has an outsized effect on prefrontal dopamine tone and on the functions the prefrontal cortex supports: working memory, executive function, attention regulation and stress response. The Val158Met polymorphism substitutes methionine for valine at codon 158 of the membrane-bound isoform; the methionine version is less thermostable and at body temperature its catalytic activity is roughly a third to a quarter that of the valine version. Met carriers tend to perform slightly better on executive-cognition and working-memory tasks (Egan et al., PNAS 2001), while a neuroimaging meta-analysis found the opposite direction, favouring Val, in emotional tasks (Mier et al., Mol Psychiatry 2010). Effect sizes are small in healthy populations and easily overwhelmed by training, sleep and context.","category":"nutrigenomics","key_variants":[{"rsid":"rs4680","name":"Val158Met (exon 4)","alleles":"Plus strand, GRCh37 (as in 23andMe raw data): G reference (Val158), A variant (Met158). COMT is on the plus strand, so the letters match the gene.","effect":"Met allele reduces enzyme thermostability; Met/Met activity is roughly a third to a quarter of Val/Val (Lachman et al., Pharmacogenetics 1996). Val/Val: faster prefrontal dopamine clearance. Met/Met: slower clearance, slightly better executive-cognition performance and more efficient prefrontal activity during working-memory tasks (Egan et al., PNAS 2001), and higher pain ratings with lower mu-opioid responses to sustained pain than heterozygotes in one PET study (Zubieta et al., Science 2003).","frequency_note":"Met allele frequency ~50% in Europeans, ~28% in East Asians, ~28% in Africans (1000 Genomes, Ensembl). Genotype frequencies in Europeans: Val/Val ~26%, Val/Met ~47%, Met/Met ~26%."},{"rsid":"rs4633","name":"rs4633 (synonymous)","alleles":"Plus strand, GRCh37 (as in 23andMe raw data): C reference, T variant (synonymous). Its effect is described only as part of the COMT haplotype with rs6269, rs4818 and rs4680: a count at this position is not on its own a reading of enzyme activity.","effect":"In strong linkage disequilibrium with rs4680. Often included in COMT haplotypes used in pain-perception research.","frequency_note":null},{"rsid":"rs4818","name":"rs4818 (exon 4, synonymous)","alleles":"Plus strand, GRCh37 (as in 23andMe raw data): C reference, G variant (synonymous). Strand-ambiguous (C/G): the letters are the same on both strands, so you can't tell which strand a file uses, and a homozygote on the other strand reads as the other allele. Its effect is described only as part of the COMT haplotype with rs6269, rs4633 and rs4680.","effect":"Synonymous variant that nonetheless alters mRNA folding and protein expression levels (Nackley et al., Science 2006). Part of the low-pain-sensitivity haplotype with rs4680 and rs4633.","frequency_note":null},{"rsid":"rs6269","name":"rs6269 (5′ UTR)","alleles":"Plus strand, GRCh37 (as in 23andMe raw data): A reference, G variant (5′ UTR). Its effect is described only as part of the COMT haplotype with rs4633, rs4818 and rs4680.","effect":"5′ UTR variant that combines with rs4633, rs4818 and rs4680 to define the LPS / APS / HPS pain-sensitivity haplotypes (at rs6269, rs4633, rs4818 and rs4680 in that order: GCGG = low, ATCA = average, ACCG = high pain sensitivity), from a single study of experimental pain (Diatchenko et al., Hum Mol Genet 2005).","frequency_note":null}],"phenotypes":["Val/Val (GG): high-activity COMT, faster prefrontal dopamine clearance","Val/Met (AG): intermediate activity","Met/Met (AA): low-activity COMT, slower prefrontal dopamine clearance","LPS (low pain sensitivity) haplotype","APS (average pain sensitivity) haplotype","HPS (high pain sensitivity) haplotype"],"clinical_relevance":"ClinVar classifies rs4680 (Val158Met) as benign (VCV000017591), and the published associations of the common COMT variants with several phenotypes have small effect sizes. Where the evidence is reasonably strong: pain perception (the LPS, APS and HPS haplotypes correlate with experimentally measured pain thresholds and with risk of temporomandibular disorder); and 22q11.2 deletion syndrome, whose cognitive and psychiatric phenotypes are driven by the deletion, not by Val158Met. Preliminary: pharmacogenomics of the COMT inhibitors entacapone and tolcapone used as adjuncts to levodopa in Parkinson's disease, where the evidence is one small randomized crossover trial in which Val/Val patients gained more ON time from a single entacapone dose than Met/Met patients (Corvol et al., Ann Neurol 2011), and no CPIC or DPWG guideline covers either drug. Where the evidence is weak or non-replicated: schizophrenia risk (early associations did not survive large GWAS), warrior-vs-worrier personality typing (pedagogically useful, but the real-world behavioural effect is small and heavily moderated by environment), and anxiety disorders (modest, inconsistent findings). Met/Met carriers are not destined to be anxious and Val/Val carriers are not immune to stress; the variant shifts a probability distribution, it does not assign a fate.","consumer_array_caveat":"rs4680 is universally included in consumer SNP arrays. Some platforms report the opposite strand and show C/T instead of G/A; the biology is the same — what matters is whether the Val (high-activity) or Met (low-activity) version is carried.","drugs":[{"drug":"entacapone","guideline":null,"level":null,"summary":"COMT inhibitor used as an adjunct to levodopa in Parkinson's disease. In one small randomized crossover trial (33 patients, single levodopa challenge), Val/Val carriers gained more ON time from entacapone than Met/Met carriers (Corvol et al., Ann Neurol 2011). Research finding; no CPIC or DPWG dosing guideline."},{"drug":"tolcapone","guideline":null,"level":null,"summary":"COMT inhibitor used as an adjunct to levodopa in Parkinson's disease. No CPIC or DPWG pharmacogenetic guideline covers tolcapone, and an effect of COMT genotype on its response has not been established."},{"drug":"morphine","guideline":null,"level":"CPIC C","summary":"In a study of 207 cancer pain patients, Val/Val carriers needed more morphine (155 mg/24h on average) than Met/Met carriers (95 mg/24h), suggesting COMT genotype may contribute to differences in morphine efficacy (Rakvåg et al., Pain 2005). CPIC reviewed COMT for opioids and found the evidence too limited for genotype-based recommendations (Crews et al., Clin Pharmacol Ther 2021). Study finding, not a dosing guideline."}],"sources":[{"label":"ClinVar — COMT gene entries","url":"https://www.ncbi.nlm.nih.gov/clinvar/?term=COMT%5Bgene%5D"},{"label":"OMIM 116790 — COMT","url":"https://www.omim.org/entry/116790"},{"label":"NCBI Gene 1312","url":"https://www.ncbi.nlm.nih.gov/gene/1312"},{"label":"Lachman et al., Pharmacogenetics 1996 (COMT Val158Met: three- to four-fold variation in enzyme activity)","url":"https://pubmed.ncbi.nlm.nih.gov/8807664/"},{"label":"Diatchenko et al., Hum Mol Genet 2005 (COMT LPS/APS/HPS haplotypes and pain sensitivity)","url":"https://pubmed.ncbi.nlm.nih.gov/15537663/"},{"label":"Egan et al., PNAS 2001 (Val158Met, prefrontal function)","url":"https://pubmed.ncbi.nlm.nih.gov/11381111/"},{"label":"Mier et al., Mol Psychiatry 2010 (neuroimaging meta-analysis)","url":"https://pubmed.ncbi.nlm.nih.gov/19417742/"},{"label":"Zubieta et al., Science 2003 (COMT and mu-opioid pain responses)","url":"https://pubmed.ncbi.nlm.nih.gov/12595695/"},{"label":"Rakvåg et al., Pain 2005 (COMT Val158Met and morphine requirement in cancer pain)","url":"https://pubmed.ncbi.nlm.nih.gov/15927391/"},{"label":"Kambur & Mannisto, Int Rev Neurobiol 2010 (COMT haplotypes and pain)","url":"https://pubmed.ncbi.nlm.nih.gov/21095465/"},{"label":"Corvol et al., Ann Neurol 2011 (COMT Val158Met and response to entacapone: randomized crossover trial, 33 Parkinson's patients)","url":"https://pubmed.ncbi.nlm.nih.gov/21280081/"},{"label":"Crews et al., Clin Pharmacol Ther 2021 (CPIC guideline: CYP2D6, OPRM1, COMT and opioids)","url":"https://pubmed.ncbi.nlm.nih.gov/33387367/"},{"label":"CPIC — gene–drug pairs (no CPIC guideline for COMT with entacapone or tolcapone)","url":"https://cpicpgx.org/genes-drugs/"},{"label":"Ensembl GRCh37 rs4680 population frequencies (1000 Genomes phase 3)","url":"https://grch37.ensembl.org/Homo_sapiens/Variation/Population?v=rs4680"}],"related_blog":"/blog/comt-gene-stress/","disclaimer":"Educational information only, not medical advice or diagnosis. Consult a clinician before acting on genetic information."},"meta":{"disclaimer":"Educational information only, not medical advice or diagnosis. Consult a clinician before acting on genetic information.","api_version":"2026-09-20","docs":"https://deepdna.ai/docs/","status":"live","data_as_of":"2026-10-25T21:32:19.251Z","freshness":"https://deepdna.ai/api/v1/freshness"}}