rs121918472
A SNP in the PROS1 gene on chromosome 3. Its most notable genotype is G;G: Increased venous thromboembolism risk (> 6x)
- Gene
- PROS1
- Location
- Chr 393,879,306 (GRCh38)
- Highest magnitude
- 6.0Very important
- Tested on
- 23andMe, AncestryDNA
- Minor allele frequency
- <1%
Genotypes
Plus strand, as in 23andMe and AncestryDNA files.
- G;GMost notableBadIncreased venous thromboembolism risk (> 6x)
- A;GBadLikely miscall in Ancestry data; otherwise, increased risk (~6x) for venous thromboembolism
- A;AGoodcommon in clinvar
SNPedia records rs121918472 on the minus strand: (C;C), (C;T), (T;T). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.
Related
Conditions, medicines and genes
Other PROS1 SNPs
- rs387906675C;CProtein-S deficiency; severeVery important
- rs138925964T;TClotting issues likely in infantsVery important
- rs6122A;GPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
- rs121918473C;TPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
- rs121918474C;TPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
- rs121918475A;GPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
- rs121918476C;GPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
- rs267606981A;TPartial protein-S deficiency; higher risk for blood clotting related issuesVery important
Notes
From SNPedia
Notes
aka c.1501T>C (p.Ser501Pro or S501P) The minor allele of this SNP, rs121918472(C), leads to a Protein S form known as the "Heerlen variant". Present in ~0.5% of healthy blood donors, this variant was considered to be a neutral polymorphism for many years even though it was associated with slightly reduced levels of free Protein S in plasma. However, more recently, a 2017 study based on 4,000+ VTE patients has reported that heterozygotes for this variant are at significantly increased risk for venous thromboembolism ( (OR 6.6, CI:4.0–10.6, p=1.73x10e-14).
G;G
see main rs-page for discussion
A;G
see text on main rs-page for discussion
Source and license
Adapted from rs121918472 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.
SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.