Recent studies on different commercial CMV IgM assays showed that the concordance of the outcomes for IgM antibodies between those assays is 84–95% [5,12,13,14,15,16,17,18] and that their relative sensitivity and specificity for primary infections are 54–100% and 62–100%, respectively [5,13,19,20,21,22,23,24,25]. The gene discussed is CD40LG; the disease is infection.