rs1799945
Iron overload, H63D
What this position does
The second and much milder HFE variant. On its own it causes very little; paired with C282Y it occasionally produces mild iron loading.
What each result means
| If you carry | What it means |
|---|---|
| No copies of the effect version CC | You do not carry H63D Neither copy carries H63D. |
| One copy CG | You carry one copy, which on its own does very little Common and usually of no consequence by itself. |
| Two copies GG | You carry two copies, which rarely causes iron problems by itself Rarely causes iron overload without a C282Y copy alongside it. |
This one cannot be read reliably from a home DNA test. Its two versions are mirror images of each other, so there is no way to tell which DNA strand your testing company reported. Sequencings declines it rather than guessing, and so should anything else.
How common each version is
| Ancestry group | G (the effect version) | |
|---|---|---|
| African | 1.1% | |
| American | 11.5% | |
| East Asian | 2.9% | |
| European | 17.2% | |
| South Asian | 7.1% |
1000 Genomes Project phase 3, via Ensembl, retrieved 2026-09-23. These groupings are coarse and flatten a great deal of internal diversity, particularly within Africa. A variant being common somewhere tells you where a piece of your ancestry probably comes from, and nothing else.
How many people carry each result
| Ancestry group | CC | CG | GG |
|---|---|---|---|
| African | 646 / 661 | 15 / 661 | 0 / 661 |
| European | 348 / 503 | 137 / 503 | 18 / 503 |
| East Asian | 478 / 504 | 23 / 504 | 3 / 504 |
| South Asian | 420 / 489 | 69 / 489 | 0 / 489 |
| American | 276 / 347 | 62 / 347 | 9 / 347 |
Counts of people, not modelled frequencies: every one of the 2,504 individuals sequenced by the 1000 Genomes Project phase 3, tallied by the genotype they carry. Deriving these from allele frequencies instead would assume random mating inside each group and undercount the homozygotes.
How to find out which you have
If you have taken a test with 23andMe, AncestryDNA, MyHeritage, Family Tree DNA, TellMeGen or Living DNA, this position is very likely already in the raw data file they gave you. You do not need another test.
One thing to watch if you look it up by hand: testing companies report some positions from one DNA strand and some from the other, and the file does not say which. Read the letters as they appear and you will get the opposite of the truth for some positions. Sequencings resolves that automatically.
Source
Coordinates and allele pair verified against Ensembl GRCh37. Direction of effect verified against VEP protein consequences or 1000 Genomes population frequency. Category: Health-adjacent.
Related
- rs1800562 — Iron overload, C282Y
Where this fits
Common questions
What is rs1799945?
rs1799945 is a position in the HFE gene on chromosome 6. The second and much milder HFE variant. On its own it causes very little; paired with C282Y it occasionally produces mild iron loading.
What does it mean if I have GG at rs1799945?
You carry two copies, which rarely causes iron problems by itself. Rarely causes iron overload without a C282Y copy alongside it.
What does it mean if I have CC at rs1799945?
You do not carry H63D. Neither copy carries H63D.
How do I find out my rs1799945 genotype?
If you have taken a home DNA test, this position is very likely in the raw data file you were given. Sequencings reads that file in your browser without uploading it, and resolves which DNA strand each position was reported from, which is the step most manual lookups get wrong.
This is reference information, not medical advice, and not a diagnosis. See the medical disclaimer. Category: Health-adjacent.