CD40 and multiple sclerosis: We observed highly significant associations between CD40 expression and the rs4810485 genotype in all B cell subsets (patients: P ≤ 5.10 × 10−5, controls P ≤ 4.09 × 10−6), with each copy of the multiple sclerosis risk allele rs4810485*T corresponding to lower CD40 cell surface expression levels (Figs 1 and 2).