The discordance between anti-CMV IgM positivity and low avidity anti-CMV IgG antibodies results in our study could be due to prolonged circulation of anti-CMV IgM antibodies past period of active infection (7), hence an overestimation of active CMV infection cases when considering anti-CMV IgM results only. The gene discussed is CD40LG; the disease is cytomegalovirus infection.