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Primary topic: TCN1 B12 carrier gene

TCN1 Gene and Metabolism: What It Can Mean in a Pathway Report

TCN1 is tracked as circulating B12 carrier context, not as the main cellular B12 delivery route.

What is the TCN1 gene?

TCN1 encodes haptocorrin, a B12-binding protein that carries a large share of circulating B12. It is different from TCN2, which delivers B12 to cells.

How TCN1 affects metabolism

TCN1 variants can influence measured circulating B12. That can make B12 labs harder to interpret without functional markers.

What happens when TCN1 is altered

A TCN1 signal does not prove cellular B12 deficiency. It raises the value of checking methylmalonic acid, homocysteine, and holotranscobalamin when B12 questions matter.

Curated SNP evidence for TCN1

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.

Methylation

Evidence-backed report connection

TCN1 currently has 1 curated SNPs, 1 claim-level scores, and 1 claims eligible for pathway scoring.

Open the sample report
rs34324219TCN1 circulating B12 supporting signal1 claims · 4 study rows

biomarker tendency · AC

Circulating vitamin B12 tendency

Moderate

rs34324219 AC carries one A allele in TCN1 and is associated with lower circulating vitamin B12 tendency.

TCN1 rs34324219 AC is staged as a lower circulating-B12 carrier-context genotype, not as a direct cellular B12-use measurement.

Likely effectLower biomarker tendency
Signal sizeSmall signal
Evidence supportStrong support
Report useIncluded in pathway scoring
Show study evidence
NCBI RefSNP recordidentity only · unknownNCBI RefSNP identifies rs34324219 as a TCN1-region variant. This row supports variant identity only and does not assign B12 biomarker direction.PubMed 25147783gwas · directKeene et al. reported rs34324219 A in TCN1 associated with vitamin B12 measurement in the VISP ischemic stroke population. GWAS Catalog records the association as A with beta direction decrease and P about 5e-11, supporting A as a lower circulating B12 allele.GWAS Catalog association 44386gwas · directGWAS Catalog association 44386 records rs34324219-A, mapped to TCN1, for vitamin B12 measurement with beta direction decrease. This supports the exact effect allele and B12 biomarker direction.PubMed 23754956gwas · directGrarup et al. reported rs34324219 as the strongest TCN1-locus serum B12 signal in the Icelandic data and described it as a D301Y missense variant. Public association summaries report the C allele as B12-increasing at this biallelic A/C locus, which supports A as the lower-B12 allele by contrast.

Common symptoms people report

  • B12 labs that do not match symptoms
  • fatigue or neurological symptoms with unclear B12 context
  • methylation markers that need B12 interpretation

Biomarkers to validate

Methylmalonic acid

Functional marker for cellular B12 sufficiency.

Homocysteine

Shows one-carbon pressure that can involve B12.

Holotranscobalamin

Reflects the active transport fraction of B12.

Where DNA analysis helps

DNA helps separate circulating B12 carrier context from cellular B12 delivery questions.

Example interpretation

TCN1 may add useful context when its SNP evidence lines up with the broader pathway signal.

Suggested validation: MMA, homocysteine, and holotranscobalamin.

What to do next

  • Do not rely on total serum B12 alone.
  • Compare TCN1 with TCN2 and MTR/MTRR context.
  • Use functional markers before changing B12 strategy.

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Related pages

TCN2

TCN2 B12 transport gene

MTRR

MTRR B12 recycling gene

Holotranscobalamin

holotranscobalamin and B12 transport

Homocysteine

homocysteine and methylation

B12 transport and recycling pathway

B12 transport and recycling pathway

Methylation pathway

methylation pathway explained

Is DNA metabolism analysis worth it?

is DNA metabolism analysis worth it

DNA nutrition analysis report

DNA nutrition analysis report

Related symptom angle

Slow metabolism genetics

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