General information
Globin chain involved
Status
Heterozygous
Migration zones
Migration positions
243, 283
Sickle Cell Disease: No
Thalassemic variant: No
Capillary Electrophoresis
Fractions
Value %
Hb A
73.1
Hb F
1.2
Denatured Hb
1.4
Hb Chad + Hb A2
23.7
Hb "Chad-A2"
0.6
Comments
A 23.7% expression of Hb Chad is consistent with a mutation on the Alpha2 gene (not confirmed by genotyping).
Mutation data
Heterozygous Hb Chad
Mutation
HGVS Nomenclature
Alpha2 23(B4) Glu>Lys
HBA2:c.70G>A
Hematological parameters
Name
Result
RBC Count
Normal to high
Total Hemoglobin
Normal
MCV
Normal
MCH
Normal
Blood smear
No information
Other analysis
No information
Comments on hematology
Clinical context
Clinical presentation
Normal
Clinical risk
Variant information
Stability
No data
Oxygen affinity
Slightly increased
Ethnicities in literature
Found in Black African & Asian populations: met in several Black African families from Chad, in a Chinese family in Taiwan, in Japanese families, and in Korean families
Comments on variant information
The rare variant Hb Chad has been found in combination with the mutation at codon 23 of the -alpha(3.7 kb) alpha-thal-2 gene in a family from Surinam.
Scientific Literature
Scientific references
- https://pubmed.ncbi.nlm.nih.gov/5714528/ Boyer SH. et al., Am J Hum Genet. 1968 Nov;20(6):570-8.
- https://pubmed.ncbi.nlm.nih.gov/4786652/ Blackwell RQ. et al., Trop Geogr Med. 1973 Dec;25(4):393-6.
- https://pubmed.ncbi.nlm.nih.gov/2606723/ Codrington JF. et al., Hemoglobin. 1989;13(6):543-56.
- https://pubmed.ncbi.nlm.nih.gov/6689417/ Harano T. et al., Hemoglobin. 1983;7(6):581-4.
- https://pubmed.ncbi.nlm.nih.gov/28107170/ Yun YM. et al., Clin Chem Lab Med. 2017 Jul 26;55(8):1234-1242.
- https://pubmed.ncbi.nlm.nih.gov/29365076/ Riou J. et al., Am J Clin Pathol. 2018 Jan 29;149(2):172-180.
- https://pubmed.ncbi.nlm.nih.gov/35059272/ Yoshino K. et al., Diabetol Int. 2021 Aug 13;13(1):330-335.
Globin Chain involved
Status
The term "Double Heterozygous" refers to cases of heterozygosity on different globin chain types, while the term "Compound Heterozygous" refers to cases of heterozygosity on the same globin chain type.
For example, S/G-Pest is a Double Heterozygous case (beta and alpha-globin chains are mutated) and S/C is a Compound Heterozygous case (only beta-globin chains are mutated).
Migration zones
Migration positions
Sickle Cell Disease
Thalassemic variant
Capillary Electrophoresis
Variant information
Ethnicities are provided for informational purposes only and are based on scientific literature and conference posters.
A hemoglobin variant may therefore be present in populations of ethnic origins or countries not listed here.