• Intermittent fevers, abdominal pain, large joint arthritis, enthesitis, IBP. Childhood or adolescent onset is typical, but may occur in adulthood• Risk factors: genetics (MEFV gene mutations); Turkish, Armenian, North African, Jewish, and Arab descent• Imaging: sacroiliitis indistinguishable from axSpA. This evidence concerns the gene MEFV and Sacroiliac arthritis.