Hb Tigraye or alpha 2 beta (2)79(EF3)Asp-->His(GAC-->CAC): a hemoglobin variant with increased oxygen affinity observed in an Ethiopian male

Hb Kalundborg [β79(EF3)Asp→Glu; HBB: c.240C>a], a Possible Low-affinity Hemoglobin Variant Detected during Hb A1c Measurement

A previously unknown hemoglobin (Hb) variant was detected during measurement of glycosylated Hb (Hb A_1c) after the introduction of a new high performance liquid chromatography (HPLC) apparatus. Subsequent DNA sequencing revealed a heterozygous single nucleotide substitution at codon 79 (C>A) on the β-globin gene changing an amino acid [β79(EF3)Asp→Glu; HBB: c.240C>A]. The new Hb variant was named Hb Kalundborg after the place of origin of the proband. Heterozygosity for this mutation appears to have no clinical significance in itself except for a possibly slightly lower oxygen affinity. However, it interferes with Hb A_1c measurement by HPLC, causing a falsely high Hb A_1c concentration when using the G11 apparatus with clinical implications possibly to follow.

Fetal heterozygosity for both Hb G-Hsi-Tsou and beta thalassemia: A case report

Introduction

This case report describes a fetus with compound heterozygosity for Hb G-Hsi-Tsou and beta thalassemia, diagnosed in a healthy pregnancy. To the best of our knowledge, this is the first documented case of compound heterozygosity and the woman is the second known case of heterozygosity for Hb G-Hsi-Tsou.

Case presentation

A 34-year-old woman during her first pregnancy underwent hemoglobin electrophoresis which revealed heterozygosity for Hb G-Hsi-Tsou. Hemoglobin G-Hsi-Tsou constitutes a hemoglobin variant with a structural abnormality of the beta chain, first described in 1972, but since then no other cases have been reported. After finding out that her husband was heterozygous for beta thalassemia, chorionic villus sampling revealed the embryo's heterozygosity for both Hb G-Hsi-Tsou and beta thalassemia. Due to lack of scientific data, the couple decided to end the pregnancy.

Conclusion

It was not possible to determine whether the fetus would present serious deficiencies in hematopoiesis, as Hb G-Hsi-Tsou is a variant which is not yet fully understood. What made this case even more complex was the simultaneous presence of the beta thalassemia allele.

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Electrophoresis can be used to reveal heterozygosity for Hb G-Hsi-Tsou.

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Chorionic villus sampling was performed in the case described, revealing heterozygosity for both Hb G-Hsi-Tsou and beta thalassemia.

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Hb G-Hsi-Tsou occurs due to a substitution of aspartic acid for glycine at position 79, creating an anomalous βT9 peptide.

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It was not possible to determine whether the fetus would present serious deficiencies in hematopoiesis.

Two new G gamma chain variants: Hb F-Saint-Etienne [G gamma 79(EF3)Asp-->His] and Hb F-Lyon [G gamma 97(FG4)His-->Arg]

Two new fetal hemoglobin (Hb F) variants affecting the (G)gamma chain are reported: Hb F-Saint-Etienne [G gamma 79(EF3)Asp-->His] and Hb F-Lyon [G gamma 97(FG4)His-->Arg]. These new Hb variants were found during a neonatal screening for hemoglobinopathies but characterized a few months later by our reference laboratory. The corresponding mutations are located on the external part of the Hb molecule and seem to be clinically silent.

An Ethiopian pattern of human adaptation to high-altitude hypoxia

We describe, in Ethiopia, a third successful pattern of human adaptation to high-altitude hypoxia that contrasts with both the Andean "classic" (erythrocytosis with arterial hypoxemia) and the more recently identified Tibetan (normal venous hemoglobin concentration with arterial hypoxemia) patterns. A field survey of 236 Ethiopian native residents at 3,530 m (11,650 feet), 14-86 years of age, without evidence of iron deficiency, hemoglobinopathy, or chronic inflammation, found an average hemoglobin concentration of 15.9 and 15.0 gdl for males and females, respectively, and an average oxygen saturation of hemoglobin of 95.3%. Thus, Ethiopian highlanders maintain venous hemoglobin concentrations and arterial oxygen saturation within the ranges of sea level populations, despite the unavoidable, universal decrease in the ambient oxygen tension at high altitude.