Complete deficiencies of complement C4A and C4B including 2-bp insertion in codon 1213 are genetic risk factors of systemic lupus erythematosus in Thai populations

In conclusion, both C4AQ0 and C4BQ0 are the strong predisposing factors for SLE in Thais. It was supported by the absence of either C4A or C4B deletion in healthy control. We suggested that the different racial and genetic backgrounds could alter the thresholds for requirement of C4A or C4B protein levels in immune tolerance and regulation.