Here's what we thought we knew: IgA deficiency leads to anaphylactic transfusion reactions. Not so fast! Dr. Gerald Sandler from Georgetown University noticed something when he was in charge of one of the US national reference labs: Hardly anyone with true anaphylactic reactions actually had IgA deficiency and anti-IgA! There's more to the story, and Jerry is here to share it with us (including why it's still ok to look for IgA deficiency in these patients).