RESUMO
BACKGROUND: Hemophilias A and B are X-linked bleeding disorders caused by mutations in the factor VIII and factor IX genes, respectively. Our objective was to identify the spectrum of mutations of the factor VIII and factor IX genes in Saudi Arabian population and determine the genotype and phenotype correlations by molecular dynamics (MD) simulation. METHODS: For genotyping, blood samples from Saudi Arabian patients were collected, and the genomic DNA was amplified, and then sequenced by Sanger method. For molecular simulations, we have used softwares such as CHARMM (Chemistry at Harvard Macromolecular Mechanics; http://www.charmm-gui.org) and GROMACS. In addition, the secondary structure was determined based on the solvent accessibility for the confirmation of the protein stability at the site of mutation. RESULTS: Six mutations (three novel and three known) were identified in factor VIII gene, and six mutations (one novel and five known) were identified in factor IX gene. The factor VIII novel mutations identified were c.99G>T, p. (W33C) in exon 1, c.2138 DelA, p. (N713Tfs*9) in eon14, also a novel mutation at splicing acceptor site of exon 23 c.6430 - 1G>A. In factor IX, we found a novel mutation c.855G>C, p. (E285D) in exon 8. These novel mutations were not reported in any factor VIII or factor IX databases previously. The deleterious effects of these novel mutations were confirmed by PolyPhen2 and SIFT programs. CONCLUSION: The protein functional and structural studies and the models built in this work would be appropriate for predicting the effects of deleterious amino acid substitutions causing these genetic disorders. These findings are useful for genetic counseling in the case of consanguineous marriages which is more common in the Saudi Arabia.
RESUMO
BACKGROUND: Autosomal dominant hereditary angioedema (HAE) results in episodes of subcutaneous edema in any body part and/or submucosal edema of the upper respiratory or gastrointestinal tracts. This disorder is caused by mutations in the C1NH gene, many of which have been described primarily in European patients. However, the genetic cause of HAE in Middle Eastern Arab patients has not yet been determined. METHODS: Four unrelated Arab families, in which 15 patients were diagnosed with HAE, were studied. DNA from 13 patients was analyzed for mutations in the C1NH gene by DNA sequencing. RESULTS: Three novel and 2 recurrent mutations were identified in the C1NH gene of HAE patients. In family 1, the patient was heterozygous for a novel c.856C>T and a recurrent c.1361T>A missense mutation encoding for p.Arg264Cys and p.Val432Glu, respectively. In patients from family 2, a novel c.509C>T missense mutation encoding for a p.Ser148Phe was identified. In patients from family 3, a novel c.1142delC nonsense mutation encoding for a p.Ala359AlafsX15 was discovered. In family 4, a recurrent c.1397G>A missense mutation encoding for a p.Arg444His was present. CONCLUSION: This is the first ever report of C1NH gene mutations in Middle Eastern Arab patients. Our study suggests that, despite the numerous existing mutations in the C1NH gene, there are novel and recurrent mutations in HAE patients of non-European origin. We conclude that the spectrum of C1NH gene mutations in HAE patients is wider due to the likely presence of novel and recurrent mutations in patients of other ethnicities.
