Hemoglobin Lille, α 2 [74(EF 3 ) Asp → Ala] β 2

Hb Jishui [HBA1: c.225C>G, Codon 74 (GAC>GAG), Asp→Glu]: A Novel α Chain Hemoglobin Variant Detected During Hb A1c Measurement

Here we report a novel α chain hemoglobin (Hb) variant found in a 74-year-old Chinese male. We accidentally discovered this Hb variant during the measurement of Hb A_1c by a capillary electrophoresis (CE) method (Hb A_1c program, CapillaryS3 TERA). However, Hb analysis with the Hb program of CapillaryS3 TERA and the VARIANT II™ β-Thalassemia Short Program showed no indication of the Hb variant. Sanger sequencing revealed a new missense mutation on the HBA1 gene [HBA1: c.225C>G, codon 74 (GAC>GAG), Asp→Glu]. We named it Hb Jishui after the birthplace of the proband.

In Silico Analysis of the Effects of Point Mutations on α-Globin: Implications for α-Thalassemia

Hemoglobinopathies are inherited diseases that impair the structure and function of the oxygen-carrying pigment hemoglobin (Hb). Adult Hb consists of two α and two β subunits. α-Thalassemia (α-thal) affects the genes that code for the α-globin chains, HBA1 and HBA2. Mutations can result in asymptomatic, mild or severe outcomes depending on several factors, such as mutation type, number of mutations and the location at which they occur. PredictSNP was used to estimate whether every possible single nucleotide polymorphism (SNP) would have a neutral or deleterious effect on the protein. These results were then used to create a plot of predicted tolerance to change for each residue in the protein. Tolerance to change was negatively correlated with the residue's sequence conservation score. The PredictSNP data were compared to clinical reports of 110 selected variants in the literature. There were 29 disagreements between the two data types. Some of these could be resolved by considering the role of the affected residue in binding other molecules. The three-dimensional structures of some of these variant proteins were modeled. These models helped explain variants which affect heme binding. We predict that where a point mutation alters a residue that is intolerant to change, is well conserved and or involved in interactions, it is likely to be associated with disease. Overall, the data from this study could be used alongside biochemical and clinical data to assess novel α-globin variants.