Compound heterozygote states for Hb C/Hb Malay and Hb C/Hb E in pregnancy: a molecular and hematological analysis

Hemoglobin (Hb) C (alpha2beta(2)6Glu-Lys) is a variant Hb found mainly in West Africa where individuals carrying both Hb C and Hb S (alpha2beta(2)6Glu-Val) usually have a disease similar to sickle cell disease. The Hb C molecule has reduced solubility leading to crystal formation and hemolytic anemia. We report a hitherto undescribed interaction of Hb C and Hb Malay (alpha2beta(2)19Asn-Ser) in a Thai individual. She was a 24-year-old pregnant woman with moderate anemia who had the following hematologic data; Hb 8.9 g/dl, Hct 30.0%, MCV 81.0 fl, MCH 24.1 pg, MCHC 29.7 g/dl, RDW 17.1% and instead of Hb crystal a marked number of target cell in peripheral blood was observed. Hb analysis revealed 22.5% Hb Malay, 64.6% Hb C and 4.5% Hb A2. Globin gene analyses demonstrated that she carried the betaC mutation (beta6: GAG-AAG) in trans to the betaMalay mutation (beta19: AAC-AGC). Hematologic data of the patient were compared to those of the compound heterozygote for Hb C and Hb E (alpha2beta(2)26Glu-Lys) found in 5 other unrelated Thai pregnant women and 11 pregnant women with Hb C heterozygote with or without co-inheritance of alpha-thalassemia who had much lower Hb C levels and the non-pregnant women with Hb C heterozygote and a compound Hb E/Hb Malay syndrome. Different genotype-phenotype correlations observed in these Thai patients with Hb C disorders are illustrated.