Association of Hb Q-Thailand with homozygous Hb E and heterozygous Hb Constant Spring in pregnancy.

Abstract

Hemoglobin (Hb) Q-Thailand [alpha74(EF3): Asp-->His] is an abnormal Hb found mainly in China and South-east Asian countries. Association of the alpha(Q-Thailand) allele with alpha-thalassemia has important implications in diagnosis. We report the hitherto undescribed conditions of this variant in two unrelated pregnant Thai women. Routine Hb analyses using high-performance liquid chromatography identified abnormal Hb migrating after Hb A(2) in addition to a homozygous Hb E in the proband 1 and to a heterozygous Hb Constant Spring (Hb CS) in the proband 2. Further alpha-globin gene analysis identified that the variant was caused by the GAC to CAC mutation at codon 74 of the alpha1-globin gene corresponding to the Hb Q-Thailand, detected in cis to the 4.2 kb deletional alpha-thalassemia 2 in both cases. Interaction of the alpha(Q-Thailand) with the beta(E) globin chains in the proband 1 leads to a Hb variant, namely the Hb QE. Family study of the proband 1 showed that her non-pregnant sister had the same genotype but her father was a double heterozygote for Hb E and Hb Q-Thailand in whom both Hb Q-Thailand and Hb QE were detected. Genotype-phenotype relationships observed in these families with complex hemoglobinopathies are presented and compared with those of simple homozygote for Hb E, heterozygote for Hb CS and heterozygote for Hb Q-Thailand found in other unrelated subjects. A simple DNA assay based on allele-specific polymerase chain reaction for simultaneous detection of the Hb Q-Thailand mutation and the 4.2 kb deletional alpha-thalassemia 2 determinant was developed and validated.

• Authors: Kanokwan Sanchaisuriya, Sunisa Chunpanich, Supan Fucharoen, Goonnapa Fucharoen, Pattara Sanchaisuriya, Yossombat Changtrakun
• Journal: European journal of haematology (Eur J Haematol) Vol. 74 Issue 3 Pg. 221-7 (Mar 2005) ISSN: 0902-4441 [Print] England
• PMID: 15693792 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Hemoglobins, Abnormal
• hemoglobin Q Thailand
• Globins
• Hemoglobin E
• Hemoglobin Constant Spring

Topics

• Adult
• Chromatography, High Pressure Liquid
• DNA Mutational Analysis
• Family Health
• Female
• Genotype
• Globins (genetics)
• Hemoglobin E (genetics)
• Hemoglobins, Abnormal (genetics)
• Heterozygote
• Homozygote
• Humans
• Inheritance Patterns
• Mutation
• Pregnancy
• Thailand