Usually diagnosed and discussed purely as an antibody condition, not a genetic one. The first genome-wide study of it, in 115 Japanese patients, found a locus near C1D conferring substantially elevated risk — part of a picture the paper connects to why live births stay limited even with standard treatment.
Antiphospholipid syndrome (APS) is diagnosed by a combination of clinical events and laboratory findings: in its obstetric form, that means recurrent pregnancy loss or other defined pregnancy complications, together with a positive antiphospholipid antibody test confirmed on two separate occasions. It is usually discussed purely as an acquired autoimmune, antibody-driven condition — which is accurate, but it is also why its genetics have received comparatively little study; a condition framed entirely around an antibody test is not automatically treated as worth a genome-wide search.
Sugiura-Ogasawara et al. 2017 ran the first genome-wide association study of obstetric APS specifically: 115 Japanese patients against 419 healthy controls, testing 426,344 SNPs. They identified two loci reaching significance — one in TSHR (the thyroid-stimulating hormone receptor gene) and one near C1D, the gene this page's variant sits in. Both alleles are described as conferring substantially elevated risk.
The paper frames this as a potential piece of a larger, practically important question: why live birth rates remain limited in obstetric APS even with standard anticoagulant treatment (typically low-dose aspirin plus heparin). A genetic contributor that treatment doesn't address is one candidate explanation for that gap.
Obstetric APS is diagnosed by antibody testing and clinical history, and treated with established protocols (typically low-dose aspirin and heparin) — this page's variant changes neither. It comes from one first-of-its-kind study in 115 patients, and is reported here as an early finding worth tracking, not a validated clinical marker.
A study this size, in one population, is a genuine first step rather than a settled result. The paper itself frames it that way — identifying two candidate loci is the start of a research direction, not a conclusion about mechanism or a tool ready for clinical use.
TSHR, the other locus this study found, connects to thyroid biology — a reminder that autoimmune conditions often cluster and share genetic architecture even when they present in completely different organ systems.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Obstetric Antiphospholipid Syndrome comes down to these specific, well-studied positions — not a diagnosis.
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Obstetric Antiphospholipid Syndrome. MyGeneLog™. https://www.mygenelog.com/conditions/obstetric-antiphospholipid-syndrome
No. APS is diagnosed by a positive antiphospholipid antibody test confirmed on two occasions, together with a defined clinical history. This variant is a genetic association from one early study and is not used diagnostically.
No. Standard treatment (typically low-dose aspirin and heparin) is unchanged by this finding. It comes from one first-of-its-kind study and is reported as an early research finding, not a validated clinical marker.
It is usually framed entirely as an acquired, antibody-driven autoimmune condition, which is accurate but meant its genetics were not routinely searched. This 2017 study was the first genome-wide association study of the obstetric form specifically.
The same study found a second locus, in TSHR, the thyroid-stimulating hormone receptor gene — not on this page but worth knowing about. Autoimmune conditions often share genetic architecture across organ systems, and this is one example.
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