The antenatal screening of intron 22 inversion in the gene encoding factor VIII should be optional in women without a family history of hemophilia, especially in economically less-developed countries, according to a study by Thailandese researchers published in the Application of Clinical Genetics.

This is because the rate of intron 22 inversion in around 1 in 17,064 women without a family history of the disease and the cost of screening is very high at 194,870 USD, the authors said. For the study, the researchers analyzed F8 gene mutations for intron 22 inversion in 109 patients, the most common mutation among patients with hemophilia A.

Of the 109 patients, 51 had a family history of the disease while 58 were defined as sporadic cases. The results showed that there was an intron 22 inversion in 58.6% of sporadic cases and 51.9% of hereditary cases.

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The researchers also compared the cost of finding 1 woman with no family history of hemophilia having an intron 22 inversion with the cost of treating 1 patient with hemophilia.

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They found that the cost of screening was much lower than the cost of treating 1 patient from birth to age 40 years (194,87 USD vs 378 USD).

“Although the screening of factor VIII mutation among females without family history of hemophilia is against the current practice, it has been initiated due to the inadequate treatment provided to patients with hemophilia in countries with limited resources,” the researchers wrote.

They suggest that the screening of pregnant women without a family history of hemophilia for an intron 22 inversion should be optional. If a woman is tested and the result is positive, her male baby should have a prenatal diagnostic test. If she tests negative, there is still a risk that she has a boy with hemophilia A due to another type of mutation in the F8 gene, though the risk is lower, the authors concluded.


Sasanakul W, Chuansumrit A, Sirachainan N, Kadegasem P. Prominent mutation of intron 22 inversion in sporadic hemophilia: is it worth the antenatal screening? Appl Clin Genet. 2022;15:49-54. doi:10.2147/TACG.S363132