COPA syndrome is caused by mutations in the COP- subunit of coatomer protein complex 1 (COP-I), which participates in retrograde vesicular trafficking of proteins from the Golgi to the endoplasmic reticulum (ER). Disease manifests early in life with arthritis, lung disease, kidney dysfunction and systemic inflammation associated with NFB and type I interferon. We sought to identify the upstream innate immune sensor that drives inflammation in COPA syndrome.