General information
Globin chain involved
Status
Heterozygous
Migration zones
Migration positions
97, 207
Sickle Cell Disease: No
Thalassemic variant: No
Capillary Electrophoresis
Fractions
Value %
Hb J-Toronto
20.5
Hb A
76.9
Hb "J-Toronto-A2"
0.5
Hb A2
2.1
Comments
Hb A2 is underestimated due to the separation of Hb A2 and Hb "J-Toronto-A2". The correct value of Hb A2 is the sum of these two fractions.
Mutation data
Heterozygous Hb J-Toronto
Mutation
HGVS Nomenclature
Alpha1 5(A3) Ala>Asp
HBA1:c.17C>A
Hematological parameters
Name
Result
RBC Count
Normal
Total Hemoglobin
Normal to low
MCV
Normal to low
MCH
Normal to low
Blood smear
No information
Other analysis
No information
Comments on hematology
Normal or moderate microcytosis
Clinical context
Clinical presentation
Normal
Clinical risk
No data
Variant information
Stability
Normal
Oxygen affinity
Normal
Ethnicities in literature
Found in Caucasian populations, and more rarely in Middle Eastern & Asian populations: met in some Canadian families of British origin, in a 16-year-old female from Mazandaran Province, North of Iran, in some Belgians, in some New Zealand families of British origin, and in a 1-year-old child in India
Comments on variant information
The rare variant Hb J-Toronto has been found in combination with alpha+-thalassemia (3.7kb)
Scientific Literature
Scientific references
- https://pubmed.ncbi.nlm.nih.gov/5870555/ Crookston J.H. et al., Nature. 1965 Dec 11;208(5015):1059-61.
- https://pubmed.ncbi.nlm.nih.gov/5169069/ Vella F. et al., Clin Biochem. 1971 Oct;4(3):137-40.
- https://pubmed.ncbi.nlm.nih.gov/809964/ Vella F., Acta Haematol. 1975;54(5):257-60.
- https://pubmed.ncbi.nlm.nih.gov/22755290/ Mahdavi M.R. et al., J Pak Med Assoc. 2012 Apr;62(4):396-8.
- https://pubmed.ncbi.nlm.nih.gov/25109349/ Van Laer C. et al., Acta Clin Belg. 2014 Dec;69(6):456-9.
- https://www.proquest.com/openview/2504ddea10ad2115478a71032f480be1/1?pq-origsite=gscholar&cbl=1476363 Pullon B.M., New Zealand Journal of Medical Laboratory Science, vol. 75, no. 1, Apr. 2021, pp. 6+.
- https://saspublishers.com/article/5558/download/ Jariwala, Dr et al., (2022). Scholars Journal of Medical Case Reports. 10. 690-692.
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