HLA-C and rheumatoid arthritis: Electrophoretic analysis of MHC isoforms revealed the mean percentage of type I, IIA, and IID/X isoforms were 40% (7.8), 37.6% (5.5), and 22.5% (8.9), respectively, among controls; and 36.6% (7.2), 37.3% (7.3), and 26.1% (7.7), respectively, among RA participants.