PARVOVIRUS B19-INDUCED ANEMIA AS THE PRESENTING MANIFESTATION OF X-LINKED HYPER-IGM SYNDROME

Parvovirus B19 (B19) can cause chronic anemia due to persistent infect ion in immunocompromised hosts who cannot produce neutralizing antibod y necessary for clearing B19. Three patients with X-linked hyper-IgM s yndrome (XHIM), who were all asymptomatic until they developed B19-ind uced chronic anemia at the ages of 8, 14, and 17 years, respectively, were found to have mutations of the CD40L gene, including a missense m utation (T254M), a nonsense mutation resulting in a new initiation cod on and loss of the intracellular domain (R11X), and a splice site muta tion (nt 309+2t-->a). Antibody responses to the T cell-dependent antig en, bacteriophage phi X174, were impaired, but neutralizing antibody t iters were higher than in XHIM patients with classic phenotype. All 3 patients responded to intravenous immune globulin (IVIG) treatment. Ce rtain mutations of the CD40L gene result in a mild XHIM phenotype that may become apparent following B19 infection in patients not on IVIG t herapy and therefore not protected from B19 infection.