FCN1 and Arthritis: This would explain other apparently opposite associations of ficolin-1, reported formerly in leprosy for −542A, −144C, and +33T (26), −1981A in rheumatoid arthritis (28) and earlier chronic Pseudomonas aeruginosa colonization in cystic fibrosis patients (27), as well as ficolin-1 deficiency in a mouse model of collagen Ab-induced arthritis (41).