In pregnant women, when present, symptoms of toxoplasmosis are mild and non-specific (asthenia, low-grade fever, myalgia, and usually laterocervical lymphadenopathy), therefore, the diagnosis relies only on serological tests; in immunocompetent subjects, IgG, IgM, IgA, and IgE antibodies can be detected just after two weeks from the infection. The gene discussed is CD40LG; the disease is toxoplasmosis.