Although the significant increase in specific IgG antibodies that accompanies measles infection can be confirmed using measles IgG assay, time-to-result is too long and, in practice, a confirmed diagnosis relies on detection of the viral RNA by reverse transcription PCR (RT-PCR) in the saliva or nasopharynx swabs, and/or on detection of both specific IgG and IgM in the serum or saliva of the patient [20]. The gene discussed is CD40LG; the disease is measles.