Primary cytomegalovirus infection was suspected by a serological pattern of positive IgM and IgG anti-CMV antibodies, with the following antibody titers: IgM anti-CMV > 14 and IgG anti-CMV > 250, while in the subsequent tests it was noticed that there are a decrease of IgM antibodies (IgM anti-CMV > 8) and a persistence of IgG antibodies. The gene discussed is CD40LG; the disease is cytomegalovirus infection.