Abstract Number: PB0495
Meeting: ISTH 2020 Congress
Background: Hemophilia A (HA) is a X-linked bleeding disorder caused by Factor VIII deficiency. A wide range of mutation types are responsible for this disease, being the missense mutation the more prevalent of them. The functional impact prediction of these mutations is a challenging task, since they could be pathogenic or completely innocuous.
Aims: Identify properties involved in the protein substitutions effects, to elucidate the physicochemical alterations arising from amino acid substitutions of missense mutations that determine the disorder manifestation. The presented abstract brings forward the A1 domain mutations of a more broad study we performed.
Methods: A total of 16 A1 domain mutations were selected from the factor VIII mutation database. Structural models for each mutated and wild sequence were generated using Phyre-2 software in a modeling approach. Electrostatic potential (EP) distance values from mutation models in comparison to the wild structure were extracted using the webPIPSA software. Other attributes as hydrophobicity, disulfide-bond disruptions, and solvent surface-accessible and exposure areas were assessed using Chimera interface resources. The values of each attribute were extracted and compiled altogether with amino acid replacement indexes in a Hierarchical clustering analysis using the R Studio platform with pvclust package.
Results: In electrostatic terms, 11/16 mutations show a distance from Wild Structure (WS) (table 1). All variants show hydrophobicity and surface differences to WS. The hierarchical clustering analysis separates every mutation from WS, based on the features cited and there is a separation of phenotypes in clusters (only one case grouping severe with a mild one (p.Lys67Glu with p.Glu162Lys)(Figure1).
Conclusions: Every substitution has altered one or more features indicating its role in the mutations’ separation and importance to explain the current disorder. None of the aspects can explain the disorder alone, but their combined use proved to be a good method to separate mutations from normal.
|Mutation¹||Phenotype||EP distance from WS²||Hydrophobicity modular value³ comparing to WS||Surface changes (surface solvent-acessible area and surface||Mutation¹||Phenotype||EP distance from WS²||Hydrophobicity modular value³||Surface changes (surface solvent-acessible area and surface|
|¹ Sequence changes at protein level following the Nomenclature for Description of Genetic Variations approved by Human Genome Variation Society (HGVS). The mutations and phenotype information were recovered from Factor VIII (gene) F8 variant database of EAHAD (European Association for Hemophilia and Allied Disorders) located on the domain: f8-db.eahad.org/ . ² Electrostatic potential distance values obtained from the webPIPSA generated epogram.³ The hydrophobicity value is a modular difference between wild and mutated residues. The original values varies between -4.5 (more hydrophilic) to 4.5 (more hydrophobic).|
[Table 1. Substitutions and its information about phenotype and physicochemical properties.]
To cite this abstract in AMA style:Meireles M, Bandinelli E, Vieira G. Physicochemical Changes by Missense Mutations Influences in Hemophilia A Determination [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/physicochemical-changes-by-missense-mutations-influences-in-hemophilia-a-determination/. Accessed September 24, 2023.
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