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Molecular Characterization Of The F9 Missense Variants

1Istanbul University Oncology Institute, Istanbul, Istanbul, Turkey, 2Yıldız Teknik University, İstanbul, Istanbul, Turkey, 3Gebze Tecnical University, İstanbul, Istanbul, Turkey, 4Istanbul University, Oncology Institute, İstanbul, Istanbul, Turkey, 5Gaziantep University, Medical Faculty, Department of Hematology, Gaziantep, Gaziantep, Turkey, 6Ege University Children Hospital, İzmir, Izmir, Turkey, 7Acibadem Adana Hospital, Department of Pediatric Hematology, Adana, Adana, Turkey, 8Ege University, Department of Hematology, Ege Adult Hemophilia and Thrombosis Center, İzmir, Izmir, Turkey, 9Bursa Uludag University Pediatric Hematology, Bursa, Bursa, Turkey, 10Pamukkale University Faculty of Medicine, Denizli, Denizli, Turkey, 11Ondokuz Mayıs University Medical Faculty Haed of pediatric bone marrow unit, Samsun, Samsun, Turkey, 12Erciyes University Faculty of Medicine, Kayseri, Kayseri, Turkey, 13Selcuk University, Faculty of Medicine, Konya, Konya, Turkey, 14Istanbul Arel University, İstanbul, Istanbul, Turkey

Abstract Number: PB0202

Meeting: ISTH 2022 Congress

Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Basic

Background: Genotyping in Hemophilia B (HB) is important for genetic counseling, patient management, carrier determination since carrier women also have bleeding risk. Functional characterization of gene variants is important to establish genotype-phenotype correlation. However, minority of F9 mutations were explored through in vitro expression to determine the pathogenicity mode.

Aims: The aim is to genotype F9 gene variations in HB patients in Turkey and to functionally characterize the selected F9 missense variants by in vitro expression and molecular dynamics simulation studies.

Methods: 140 HB patients in Turkey (66 Severe, 39 Moderate, 18 Mild, 19 Unknown), have been being screened for a F9 gene variation by HRM analysis and the variants were identified by direct DNA sequencing. Molecular dynamics simulations for the F9 gene variants were performed by using the GROMACS 5.1.4 software to analyze the conformational effects of the changes. Ethical approval for this study was obtained from the ethical committee of Istanbul Arel University.

Results: HRM analysis and direct DNA sequencing revealed that 60 of the patients had 27 different F9 gene variants. The most common type was missense variation with 59,25% frequency, including one novel variation (p.166Asn>Lys). The most common missense variant was p.194Thr>Ala. Among the patients having p.194Thr>Ala, 9 were severe, 11 were moderate, 4 were mild HB patients. Molecular dynamics simulations for p.194Thr>Ala, p.226 Arg>Gln and p.318 Lys>Arg revealed that p.194Thr>Ala, p.226 Arg>Gln changes caused significant alterations, compared to WT structure while p.318 Lys>Arg did not.

Conclusion(s): The preliminary data demonstrated that the most common F9 variation in the HB population in Turkey is p.194Thr>Ala (50%). Polyphen analysis revealed that it is a benign alteration. However, ESE finder analysis revealed that it creates additional SR protein binding. Molecular dynamics simulations demonstrated that it severely affects F9 protein structure. In vitro expression studies will demonstrate its effect in a heterologous expression system.

To cite this abstract in AMA style:

Zulfikar O, Genç S, Ozbil M, Koc B, Okan V, Kavaklı K, Antmen B, Sahin F, Meral Gunes A, Ay Y, Albayrak C, Unal E, Dagli M, Berber E. Molecular Characterization Of The F9 Missense Variants [abstract]. https://abstracts.isth.org/abstract/molecular-characterization-of-the-f9-missense-variants/. Accessed October 2, 2023.

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