Like most forms of autoimmune disorders, PsA has no known single cause and doctors don’t know exactly what triggers it. Researchers believe PsA is linked to genetic factors and can be triggered by an infection, injury or stress. 15% of patients reporting having a similar history of arthritis, psoriasis and back inflammation in their family members. In 70% of patients, skin disorders (psoriasis) start before joint problem. Therefore, if you have psoriasis it is important to tell your dermatologist if you have any aches and pains. Not everyone who has psoriasis develops PsA, while around 30% of them may develop PsA.