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Primary topic: HDC histamine production gene

HDC Gene and Metabolism: What It Means for Your Body

HDC matters when histamine production itself may be part of the problem rather than only clearance.

What is the HDC gene?

HDC helps convert histidine into histamine. That makes it a production-side gene rather than a clearance-side one.

How HDC affects metabolism

If HDC-related signaling is more active, histamine-related symptoms can become easier to trigger when clearance is also under strain.

What happens when HDC is altered

Altered HDC function does not prove high histamine output in practice, but it is useful context when symptoms, triggers, and clearance genes all point the same way.

Curated SNP evidence for HDC

These SNPs come from the approved study-level evidence model. Each claim is scored from curated study rows, then gated before it can influence pathway scoring.

Histamine

Evidence-backed report connection

HDC currently has 2 curated SNPs, 6 claim-level scores, and 0 claims eligible for pathway scoring.

Open the sample report
rs17740607HDC supporting signal3 claims · 9 study rows

unknown · AA

HDC unscored target

Not used for pathway scoring

rs17740607 AA has no scored directional claim for HDC unscored target.

HDC rs17740607 is treated as biologically relevant but not interpretable as a clear genotype-effect tendency from current end-user-safe evidence.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs17740607 in HDC, the histidine decarboxylase gene, and annotate coding consequences including missense changes. This supports HDC as the gene context but does not establish a dependable user-facing activity direction.PubMed 20608921other · loose proxyGervasini et al. analyzed the HDC Thr31Met variant rs17740607 in patients with allergic rhinitis and healthy controls. The abstract reports the variant as part of HDC variability research, but the main statistically significant rhinitis association was reported for rs2073440 rather than rs17740607.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs17740607 Met31Thr among relevant nonsynonymous HDC polymorphisms. This supports biological relevance, but not a clear standalone direction for histamine production, enzyme activity, or symptom tendency.

unknown · AG

HDC unscored target

Not used for pathway scoring

rs17740607 AG has no scored directional claim for HDC unscored target.

HDC rs17740607 is treated as biologically relevant but not interpretable as a clear genotype-effect tendency from current end-user-safe evidence.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs17740607 in HDC, the histidine decarboxylase gene, and annotate coding consequences including missense changes. This supports HDC as the gene context but does not establish a dependable user-facing activity direction.PubMed 20608921other · loose proxyGervasini et al. analyzed the HDC Thr31Met variant rs17740607 in patients with allergic rhinitis and healthy controls. The abstract reports the variant as part of HDC variability research, but the main statistically significant rhinitis association was reported for rs2073440 rather than rs17740607.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs17740607 Met31Thr among relevant nonsynonymous HDC polymorphisms. This supports biological relevance, but not a clear standalone direction for histamine production, enzyme activity, or symptom tendency.

unknown · GG

HDC unscored target

Not used for pathway scoring

rs17740607 GG has no scored directional claim for HDC unscored target.

HDC rs17740607 is treated as biologically relevant but not interpretable as a clear genotype-effect tendency from current end-user-safe evidence.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs17740607 in HDC, the histidine decarboxylase gene, and annotate coding consequences including missense changes. This supports HDC as the gene context but does not establish a dependable user-facing activity direction.PubMed 20608921other · loose proxyGervasini et al. analyzed the HDC Thr31Met variant rs17740607 in patients with allergic rhinitis and healthy controls. The abstract reports the variant as part of HDC variability research, but the main statistically significant rhinitis association was reported for rs2073440 rather than rs17740607.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs17740607 Met31Thr among relevant nonsynonymous HDC polymorphisms. This supports biological relevance, but not a clear standalone direction for histamine production, enzyme activity, or symptom tendency.
rs2073440HDC supporting signal3 claims · 9 study rows

unknown · GG

HDC unscored target

Not used for pathway scoring

rs2073440 GG has no scored directional claim for HDC unscored target.

HDC rs2073440 is recognized as a coding histidine-decarboxylase variant, but it is not scored as a clear activity or biomarker tendency from genotype alone.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs2073440 in HDC, the histidine decarboxylase gene, and annotate it as a coding variant with a missense consequence for one allele. This supports HDC as the gene context but does not by itself establish an end-user enzyme-activity direction.PubMed 20608921other · close proxyGervasini et al. analyzed the HDC Glu644Asp variant rs2073440 in allergic rhinitis and reported an association for homozygous Glu644 carriers in the studied population. Because this is a clinical association rather than a direct histidine-decarboxylase activity measurement, the genotype effect is kept neutral with target unknown.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs2073440 Asp644Glu among relevant nonsynonymous HDC polymorphisms. The review context supports biological relevance, but not a reliable standalone direction for histamine production or enzyme activity from genotype alone.

unknown · GT

HDC unscored target

Not used for pathway scoring

rs2073440 GT has no scored directional claim for HDC unscored target.

HDC rs2073440 is recognized as a coding histidine-decarboxylase variant, but it is not scored as a clear activity or biomarker tendency from genotype alone.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs2073440 in HDC, the histidine decarboxylase gene, and annotate it as a coding variant with a missense consequence for one allele. This supports HDC as the gene context but does not by itself establish an end-user enzyme-activity direction.PubMed 20608921other · close proxyGervasini et al. analyzed the HDC Glu644Asp variant rs2073440 in allergic rhinitis and reported an association for homozygous Glu644 carriers in the studied population. Because this is a clinical association rather than a direct histidine-decarboxylase activity measurement, the genotype effect is kept neutral with target unknown.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs2073440 Asp644Glu among relevant nonsynonymous HDC polymorphisms. The review context supports biological relevance, but not a reliable standalone direction for histamine production or enzyme activity from genotype alone.

unknown · TT

HDC unscored target

Not used for pathway scoring

rs2073440 TT has no scored directional claim for HDC unscored target.

HDC rs2073440 is recognized as a coding histidine-decarboxylase variant, but it is not scored as a clear activity or biomarker tendency from genotype alone.

Likely effectNo clear DNA signal
Signal sizeMinimal signal
Evidence supportVery limited support
Report useEvidence only, not scored
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP data place rs2073440 in HDC, the histidine decarboxylase gene, and annotate it as a coding variant with a missense consequence for one allele. This supports HDC as the gene context but does not by itself establish an end-user enzyme-activity direction.PubMed 20608921other · close proxyGervasini et al. analyzed the HDC Glu644Asp variant rs2073440 in allergic rhinitis and reported an association for homozygous Glu644 carriers in the studied population. Because this is a clinical association rather than a direct histidine-decarboxylase activity measurement, the genotype effect is kept neutral with target unknown.PubMed 19450133review · loose proxyA histamine pharmacogenomics review lists rs2073440 Asp644Glu among relevant nonsynonymous HDC polymorphisms. The review context supports biological relevance, but not a reliable standalone direction for histamine production or enzyme activity from genotype alone.

Common symptoms people report

  • histamine-like reactions with unclear trigger thresholds
  • flushing or itchiness under load
  • symptom patterns that feel more production-driven than dietary alone

Biomarkers to validate

Plasma histamine

Useful when production-side context matters.

Tryptase

Adds mast-cell-related context.

Trigger tracking

Helps connect production load to real-world patterns.

Where DNA analysis helps

DNA can help distinguish production-side context from clearance-only discussions inside a histamine review.

Example Insight

Your histamine pattern may involve both production and clearance rather than only one side of the pathway.

Suggested validation: plasma histamine plus tryptase.

What to do next

  • Use plasma histamine or tryptase context before assuming production is elevated.
  • Review HDC together with DAO and HNMT when the pattern looks histamine-driven.
  • Treat the gene as context for validation, not as proof.

Upload your DNA file and receive a structured metabolic pathway analysis with prioritized insights and suggested validation markers.

Get My DNA Report

Related pages

DAO

DAO gene histamine metabolism

HNMT

HNMT gene histamine metabolism

DAO activity

DAO activity and histamine clearance

Tryptase

tryptase and histamine context

Histamine clearance pathway

histamine clearance pathway

Inflammation and immune signaling pathway

inflammation immune signaling pathway

Is this medical advice?

is this medical advice

Generic DNA report vs pathway analysis

generic DNA report vs pathway analysis

Related symptom angle

Histamine intolerance genetics

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