A derived trait that measures total core fucose (Fn total) was also significantly decreased, but the decrease in fucosylation was much more evident when this trait was decomposed into Fn (all glycans with core fucose that do not contain bisecting GlcNAc), which was decreased in SLE, and FBn (all glycans with core fucose that contain bisecting GlcNAc), which was increased in SLE. The gene discussed is FBN1; the disease is systemic lupus erythematosus.