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Caitlin Raymond: Practicing at the Edge of ABO – Navigating Rare A Subgroups

Caitlin Raymond/LinkedIn

Jan 18, 2026, 09:53

Caitlin Raymond: Practicing at the Edge of ABO – Navigating Rare A Subgroups

Caitlin Raymond, Assistant Professor of Pathology and Transfusion Medicine at the University of Wisconsin-Madison, shared on LinkedIn:

”I just published a new post on Blood, Bytes, and Beyond: “Practicing at the Edge of ABO: Navigating Rare A Subgroups.”

In transfusion medicine, we talk a lot about “weak A” phenotypes — but biologically and clinically, they’re not all the same.

A3, Aw, and Ael arise through different mechanisms, carry different degrees of antigen expression, and sit in very different evidence spaces when it comes to transfusion risk.

This piece grew out of a real on-service case, where the literature didn’t quite tell us what to do, and judgment mattered as much as data.

It’s a reflection on how we make conservative decisions when incidence data are sparse, case reports loom large, and the downside of being wrong is asymmetric.

If you work in transfusion medicine, blood banking, or laboratory medicine more broadly — or if you’re interested in how clinicians navigate uncertainty at the bedside — I’d love for you to read it.”

Read the full post here.

Caitlin Raymond: Practicing at the Edge of ABO - Navigating Rare A Subgroups