Intron 22 inversion real-time polymerase chain reaction detection in haemophilia A families from central South Africa
Background. Intron 22 inversion (inv22) may account for 45% of all cases of severe haemophilia A. Haemophilia A is underdiagnosed in South Africa (SA), and owing to limited resources the genotypes of most haemophilia A patients are unknown.
Objectives. To screen the haemophilia A population in central SA for inv22 using two novel detection methods.
Methods. We recruited 62 participants from 27 families affected by haemophilia A in Free State and Northern Cape provinces. We screened for inv22 with our previously reported conventional polymerase chain reaction (PCR) method, as well as with a newly developed real-time PCR method. Sanger sequencing was performed to confirm the PCR results.
Results. With the real-time PCR method, 10 of the severe haemophilia A patients and 3 carriers tested inv22-positive. The conventional PCR method and real-time PCR results were comparable in all but one case, where the discrepancy was attributed to sample-specific degradation. Inv22 was found in 29.4% of the severe haemophilia A population and 22.2% of the potential carriers. The inv22 status of most SA haemophilia A patients is currently unknown. The 29.4% of haemophilia A patients who were positive for inv22 was lower than the expected 45%, which could indicate a more prominent mutation than inv22 in the SA population.
Conclusions. The above finding needs to be confirmed by performing comprehensive factor VIII gene (F8) genotyping on the remainder of the haemophilia A patients in SA. The study contributes to genetic research in haemophilia A and lays a foundation for future research in haemophilia A genetics in SA.
J F Kloppers, Department of Haematology and Cell Biology, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa; Universitas Academic Business Unit, National Health Laboratory Service, Bloemfontein, South Africa
G M Marx, Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein, South Africa
W J Janse van Rensburg, Department of Haematology and Cell Biology, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa; Human Molecular Biology Unit, School of Biomedical Sciences, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
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Date published: 2019-10-31
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