IthaID: 2285

Names and Sequences

Functionality: Globin gene causative mutation Pathogenicity: Pathogenic / Likely Pathogenic
Common Name: CD 20 CAC>CCC [His>Pro] HGVS Name: HBA1:c.62A>C
Hb Name: Hb Fulton-Georgia Protein Info: α1 20(B1) His>Pro

Context nucleotide sequence:

Protein sequence:

Also known as: Hb Anderlecht

Comments: Initially identified by protein analysis as a His>Pro change at position α20 (α1 or α2) in a Congolese newborn and his mother and was reported as a hematologically and clinically silent variant. It was later detected by sequencing in an African-American as an α1 gene change. The α20 residue is found in the B helix, external in the Hb structure where any change in hydrophobicity leads to a large effect on the mobility. This variant is detectable by various electrophoretic methods (IEF, CAE alkaline, Citrate agar, HPLC). Molecular modelling showed that α20 His>Pro substitution did not disrupt helical structure or impact interchain interactions. The histine at α20 is likely involved in the axial intermolecular contacts of the deoxyHb S fibers, making a polar bridge with glutamic acid at β20. It is speculated that the His>Pro change could modify the rate of polymerization of deoxyHb S and the clinical severity of SCD. However, the coinheritance of this variant with heterozygous -α3.7 and Hb SC disease in the African-American proband was associated with a mild phenotype, consisting of microcytosis and anisocytosis, but no anemia or other hematological abnormality.

We follow the HGVS sequence variant nomenclature and IUPAC standards.

External Links


Hemoglobinopathy Group: Structural Haemoglobinopathy
Hemoglobinopathy Subgroup: α-chain variant
Allele Phenotype:N/A
Stability: N/A
Oxygen Affinity: N/A
Associated Phenotypes: N/A


Chromosome: 16
Locus: NG_000006.1
Locus Location: 37641
Size: 1 bp
Located at: α1
Specific Location: Exon 1

Other details

Type of Mutation: Point-Mutation(Substitution)
Effect on Gene/Protein Function: Missense codons (Protein Structure)
Ethnic Origin: African-American, Congolese
Molecular mechanism: Altered secondary structure
Inheritance: Recessive
DNA Sequence Determined: Yes

In silico pathogenicity prediction

Sequence Viewer

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Publications / Origin

  1. Cotton F, Wajcman H, Hansen V, Lin C, Jotzo K, Haumont D, Promé D, Riou J, Miyazaki A, Galactéros F, Vertongen F, Gulbis B, Hb Anderlecht [alpha20(B1)His-->Pro]: a silent variant found in a Congolese newborn., Hemoglobin , 24(4), 299-304, 2000 PubMed
  2. Zhuang L, Patel N, Bryant S, Kutlar A, Kutlar F, Young AN, Hb Fulton-Georgia [α20(B1)His→Pro; HBA1: c.62A>C]: A New α-Globin Variant Coinherited with α-Thalassemia-2 (3.7 kb deletion) and Hb SC Disease., Hemoglobin , 37(5), 481-5, 2013 PubMed
Created on 2013-10-09 14:49:51, Last reviewed on 2023-04-28 09:45:28 (Show full history)

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