Compound Heterozygous Hemoglobin Minneapolis-Laos and Codon 41/42 (-TTCT) in a Thai Female Adult: A Case Report and Literature Review.

Abstract

Thalassemia is a prevalent genetic disorder in Southeast Asia. The Hemoglobin Minneapolis-Laos variant is very rarely reported with only two previously published reports that profile a total of three patients. Here, we present the first reported case of compound heterozygous β zero (β0)-thalassemia and Hemoglobin Minneapolis-Laos in a 46-year-old Thai female. She presented at Siriraj Hospital (Bangkok, Thailand) with chronic microcytic anemia, which is a more severe phenotype than would be expected from either trait alone. Initial hemoglobin electrophoresis via high-performance liquid chromatography and capillary electrophoresis revealed elevated hemoglobin A2 (5.5% and 6.3%, respectively), which is a finding consistent with a β-thalassemia trait, but this finding failed to explain the full extent of her anemia. Next-generation sequencing was then performed to investigate for a congenital red blood cell disorder. The results identified the following two mutations in the β-globin gene (HBB): heterozygous β0-thalassemia codon 41/42 (-TTCT), and HBB c.356T >A, the latter of which is consistent with hemoglobin Minneapolis-Laos. This case highlights the importance of advanced genetic testing to diagnose rare hemoglobin variants that cannot be identified by conventional investigation and further contributes to our understanding of this rare combination's clinical phenotype.