Immune Deficiency Foundation - You may be wondering why your friend or family member living with primary immunodeficiency disease (PI) calls themselves a zebra, wears zebra print clothing and says things like, “
Immune Deficiency Foundation - THINK ZEBRA! In medical school, many doctors learn the saying, “when you hear hoof beats, think horses, not zebras,” and are taught to focus on the likeliest possibilities
![Characteristics of Ig Products Used to Treat PI Licensed for Use in the US | Immune Deficiency Foundation Characteristics of Ig Products Used to Treat PI Licensed for Use in the US | Immune Deficiency Foundation](https://primaryimmune.org/sites/default/files/images/igchartpic.png)