We’ve expanded our KIR–HLA compatibility testing to include maternal HLA-C typing alongside paternal HLA-C. This update provides a more complete immune compatibility evaluation and reflects our commitment to moving beyond standard. New evidence shows that maternal HLA-C matters too. That’s why we’ve added it to our KIR–HLA testing — delivering a more comprehensive and clinically meaningful assessment for immune-related fertility risks.
Maternal HLA-C: New Immune marker for implantation failure risk
Until recently, fertility diagnostics assessed immune compatibility by testing the maternal KIR genotype and only the paternal HLA-C type. Recent studies had suggested that when a woman carried the KIR AA genotype and the father carried an HLA-C2 allele, the risk of implantation failure, miscarriage, and poor placental development increased. At the time, maternal HLA-C was considered a fixed background factor — something that could not be influenced or managed. Clinical focus therefore centered on paternal HLA-C, which determined whether the fetus might inherit the “at-risk” C2 allele.
This approach made sense when no reliable treatments existed to address KIR–HLA mismatch. However, growing scientific evidence has changed our understanding. New research shows that uterine natural killer (uNK) cells do not distinguish between self and non-self HLA-C. Instead, they react to any C2 present on the embryo’s surface — including maternally inherited alleles. This means maternal HLA-C2 also contributes to immune signaling at the maternal–fetal interface and may influence outcomes, particularly in women with the inhibitory KIR AA genotype.
What This Means for Patients
To provide a more complete and accurate risk assessment, and especially now that effective immunomodulatory treatments are available, we have updated our protocols. Our KIR–HLA compatibility testing now includes maternal HLA-C typing, alongside paternal HLA-C and maternal KIR genotyping. This evolution in testing allows us to capture the full picture of maternal–fetal immune interactions and to guide care more precisely.
Important Update for Patients Who Have Completed Our RPL, Alloimmunity, or KIR–HLA Tests
If you previously completed our recurrent pregnancy loss (RPL), alloimmunity, or KIR–HLA testing, and were identified as having a KIR AA genotype but no paternal HLA-C2 risk, you may have been classified in the low-risk category.
New evidence indicates that maternal HLA-C itself may also contribute to risk in certain scenarios. For this reason, we now recommend an additional Maternal HLA-C Typing Test.
By completing this test, we will be able to reanalyze your results with the latest scientific insights and, if necessary, adjust your personalized treatment plan accordingly to optimize your chances of success.
If you have not yet achieved pregnancy despite previous evaluations, this new test may provide valuable additional information to guide your care.
Our Commitment
At Fertilysis, we are committed to moving beyond standard care. By continuously updating our protocols in line with the latest evidence, we aim to provide the most comprehensive immune compatibility evaluations available, helping patients and clinicians make better-informed decisions for successful outcomes.
The test can be requested as a single add-on to the Reproductive Immunology panels.
Find the test here
