General information
Globin chain involved
Status
Heterozygous
Migration zones
Migration positions
201, 271
Sickle Cell Disease: No
Thalassemic variant: No
Capillary Electrophoresis
Fractions
Value %
Hb A
79.4
Hb G-Norfolk
18.0
Hb A2
2.1
Hb "G-Norfolk-A2"
0.5
Comments
Hb A2 is underestimated due to the separation of Hb A2 and Hb "G-Norfolk-A2". The correct value of Hb A2 is the sum of these two fractions.
A 18.0% expression of Hb G-Norfolk is consistent with an Alpha1 gene mutation (confirmed by genotyping).
Mutation data
Heterozygous Hb G-Norfolk
Mutation
HGVS Nomenclature
Alpha2 or Alpha1 85(F6) Asp>Asn
HBA2:c.256G>A (or HBA1)
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
Mild erythrocytosis
Clinical context
Clinical presentation
Normal
Clinical risk
No data
Variant information
Stability
Normal
Oxygen affinity
Increased
Ethnicities in literature
Found in Caucasian & Asian populations: met in a few Caucasian families (alpha 1 & 2) in England, France and Canada, in Chinese patients (alpha 2), and also in a 15-year-old male and his relatives from Turkey (alpha 2)
Comments on variant information
Scientific Literature
Scientific references
- https://pubmed.ncbi.nlm.nih.gov/1115797/ Lorkin PA. et al., Biochim Biophys Acta. 1975 Jan 30;379(1):22-7.
- https://pubmed.ncbi.nlm.nih.gov/234399/ Cohen-Solal M. et al., FEBS Lett. 1975 Feb 1;50(2):163-7.
- https://pubmed.ncbi.nlm.nih.gov/21266019/ Khalil MS. et al., Int J Lab Hematol. 2011 Jun;33(3):318-25.
- https://pubmed.ncbi.nlm.nih.gov/29365076/ Riou J. et al., Am J Clin Pathol. 2018 Jan 29;149(2):172-180.
- https://www.degruyterbrill.com/document/doi/10.1515/tjb-2019-0476/html Ünal Hülya et al., Turkish Journal of Biochemistry, vol. 46, no. 1, 2021, pp. 97-102.
- https://pubmed.ncbi.nlm.nih.gov/34690349/ Luo S. et al., J Hum Genet. 2022 Apr;67(4):183-195.
Links to official library websites
- https://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=129 HbVar database ID 129 - Hb G-Norfolk
- https://www.ithanet.eu/db/ithagenes?ithaID=639 IthaNet portal ID 639 - Hb G-Norfolk (alpha 1)
- https://www.ithanet.eu/db/ithagenes?ithaID=3952 IthaNet portal ID 3952 - Hb G-Norfolk (alpha 2)
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
In some cases (homozygotes, combination of the variant with thalassemia, transfused patients, degraded samples or unstable variants), the variation in the migration position may be greater than +/- 1 point.
For profiles with thalassemia, only Hb A2 and Hb F peaks, if present, are listed with 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.
Hematological Parameters