[Hereditary hemoglobin H disease in Japanese siblings diagnosed by human parvovirus B19 infection]

Hereditary hemoglobin H (HbH) disease was diagnosed in 2 Japanese sisters who presented with aplastic crisis following acute human parvovirus B19 (HPV B19) infection. The proband, an 8-year-old girl, developed persistent fever and pallor, and samples of her peripheral blood showed hypochromic microcytic anemia. Other laboratory data were consistent with hemolytic anemia. Fever and signs of hypochromic microcytic anemia also developed in her sister 9 days later. Cation exchange HPLC analysis of their hemoglobin revealed abnormal hemoglobin migrating faster than HbF, a finding consistent with HbH. Although they presented neither arthralgia nor skin rash, we concluded that their aplastic crisis was induced by HPV B19, because HPV B19 DNA was detected in samples of their peripheral blood by PCR analysis, and HPV B19 IgM and IgG antibody titers were elevated. A genetic analysis of the alpha-globin gene in both sisters and their parents disclosed that the father was heterozygous for alpha-Thal-2, the mother, heterozygous for alpha-Thal-1, and the proband and her sister, double heterozygous for alpha-Thal-1 and alpha-Thal-2. alpha-Thal-2 is a 3.7 kb-deletion allele.