Anemia and hydrops in a fetus with homozygous hemoglobin constant spring.

Hemoglobin Constant Spring (Hb CS) is an unstable hemoglobin (Hb) variant that results from a nucleotide substitution at the termination codon of the alpha2-globin gene. The compound heterozygosity of alpha-thalassemia and Hb CS (--/alphaCSalpha) results in a Hb H/CS disease which is clinically more severe than deletional Hb H disease. Homozygosity of Hb CS (alphaCSalpha/alphaCSalpha) is generally characterized with mild hemolytic anemia, jaundice, and splenomegaly. The authors report 1 case with Hb CS homozygosity who presented with fetal anemia and hydrops. Intrauterine transfusions were given which rendered a favorable outcome. This report demonstrates an unusual and serious in utero complication in a fetus with Hb CS/CS.