Although she had an IgG antibody to parvovirus B19, this is seen in 30% to 60% of adults, and in more than 80% of adults over the age of 50, and indicates previous exposure.28, , -31 Her IgM antibody titer was low and this combination precludes an acute infection, since elevated IgM titers should be concurrent with the cytopenias.28 Her hepatitis serologies were negative (hepatitis A, B, C and cytomegalovirus). The gene discussed is CD40LG; the disease is hepatitis A virus infection.