How we diagnose and manage altered oxygen affinity hemoglobin variants

Abstract

Altered oxygen affinity variant hemoglobins (Hbs) are caused by mutations of the globin genes.Changes in Hb oxygen affinity shift the oxygen dissociation curve, and can be identified by abnormal p50 measurements of patient red blood cells. Variants are categorized as either low oxygen affinity (high p50) or high oxygen affinity (low p50). Accurate diagnosis requires recognition of typical clinical and laboratory findings. In this case-based review, we present two patients with altered oxygen affinity variants, illustrating barriers to prompt and accurate diagnosis, and issues in management. We then review pathophysiology, diagnostic tests, clinical features, and management strategies.

A broad diversity in oxygen affinity to haemoglobin

“…We assume that cellular oxygen availability is similar in women and men at rest, due to a final balance in oxygen carrying capacity of the blood (Hb level) and the ability to release oxygen to the tissue (p50). Our data, thus, contribute to recent reports showing a correlation of Hb level and Hb-O 2 affinity 49,50 .…”

Hb Angers: A new α2‐globin variant [α2 (140)(HC2) Tyr → Ser; HBA2: C.422 A>C] with increased oxygen affinity leading to erythrocytosis

“…5 These rare variants are in most cases sporadic, transmitted in a dominant manner, and are usually suspected in patients with long-lasting erythrocytosis. 3,6 A mandatory part of the diagnosis is the estimation of the p50, which is nowadays calculated with data obtained from a blood gas analyzers with a venous blood sample. In this case report, the comparison of OEC results with blood gas calculations shows a greater left-shift with OEV (16.5 mm Hg versus 22.3 mm Hg)…”

“…All authors have read and approved the final version of the manuscript. Frederic Galacteros MD 4,6 Henri Wajcman MD-PhD 4…”

Genetic investigation of haemoglobinopathies in a large cohort of asymptomatic individuals reveals a higher carrier rate for β-thalassaemia in Sichuan Province (Southwestern China)

“…1 , 2 The substitution, mutation, and fusion of genes lead to changes in the primary structure of the globin gene, resulting in altered biological properties of haemoglobin, such as solubility, oxygen affinity, molecular configuration, and stability. 3 Clinical manifestations may include haemolytic anaemia and methemoglobinaemia, such as the most common abnormal haemoglobin E. 4 Thalassaemia, also known as Mediterranean anaemia, is characterized by the lack or decrease in one or more of the globin peptide chain of haemoglobin, causing changes in the haemoglobin composition. The clinical symptoms of thalassaemia vary from mild to severe, with chronic progressive haemolytic anaemia being the most common.…”