Combinations of β chain abnormal hemoglobins with each other or with β-thalassemia determinants with known mutations: influence on phenotype

Abstract

Hematological and hemoglobin (Hb) data are presented for numerous patients with compound heterozygosities for different β chain variants and for a β chain variant with different β-thalassemia (β-thal) alleles. Considerable variations, which result from the type of β chain variant and β-thal mutation, can be noted. The comparison again emphasizes the importance of determining the diagnoses at the molecular level to aid the physician in the management of patients with different combinations of abnormalities. Simplification and commercialization of modern technology may make the introduction of this approach in some clinical chemistry laboratories possible.

Jamaican Sβ+‐thalassaemia: mutations and haematology

“…The three commonest mutations were all associated with a milder form of Sβ + ‐thalassaemia, higher total haemoglobin and HbA levels, consistent with those reported by Huisman (1997). Mutations within the promoter elements appeared to have higher HbF levels (average 5.3–8.0%) than mutations within the gene or downstream (average 2.6–5.0%).…”

Molecular characterization of hemoglobin C in Thailand

“…Notably, the concentration of Hb E in Hb EC compound heterozygotes as shown in Table I (32.9%-36.9%) is obviously higher than in typical Hb E heterozygotes usually encountered in our laboratory (25.0%-30.0%) [15]. It is apparent therefore that the decrease in the rate of ␣␤ C dimer formation has indirectly promoted the ␣␤ E dimerization resembling that observed with Hb SE syndrome [16].…”

Identification and reporting of common hemoglobin disorders: A review

“…On peripheral blood smear, some of the red blood cells will contain characteristic Hb C crystals, and many RBCs demonstrate targetoid morphology or a folded configuration (21). Coinheritance of Hb variants S and O-Arab causes Hb S-O-Arab disease, which is characterized by a greater proportion of Hb S compared to Hb O-Arab (79). Hb O-Arab is produced by an amino acid substitution of lysine for glutamate at position 121 on the β-chain.…”

“…Double heterozygosity of Hb S and E, or Hb SE disease, is infrequent due to differing ethnic distributions of these two variants (21). In general, the clinical phenotype is mild, characterized by a mild microcytic anemia with infrequent sickling complications (79,81,82).…”