PRTN3 and granulomatosis with polyangiitis: Genetic defects in alpha-1 antitrypsin, proteinase 3 gene, major history compatible complex class II gene, bacterial infections (staphylococci), virus (hepatitis C, cytomegalovirus, and Epstein-Barr virus), and medications like hydralazine, allopurinol, and phenytoin are other risk factors for GPA [8].