Hb Sun Prairie: Diagnostic Pitfalls in Thalassemic Hemoglobinopathies

Abstract

We report an Asian Indian family in which two daughters have Hb Sun Prairie, a known unstable α2-globin variant [codon 130, GCT → CCT; α2 130(H13)Ala → Proβ2]. While the homozygous probands have chronic hemolysis - the same phenotype as previously reported, the heterozygous parents are asymptomatic with a thalassemia carrier phenotype, distinctfrom the chronic hemolytic state previously described in a heterozygote. Unlike the earlier cases in which family studies were not available, this family clearly exhibits autosomal recessive inheritance, unusual amongst variants within the same region of helix H. Globin chain biosynthesis ratios initially suggested a β-thalassemic hemoglobinopathy - this was excluded by normal sequence analysis of both β-globin genes. This case report further illustrates the complexity of phenotypes in the thalassemic hemoglobinopathies. It also demonstrates inversion of the α/β-globin chain biosynthesis ratio, a