title: Analysis of the novel factor X gene mutation Glu51Lys in two families with factor X-Riyadh anomaly.
abstract: Two families with 'factor X(FX)-Riyadh' have been identified (one of them related to the originally reported family). Affected members of both families exhibit prolongation in prothrombin time (PT) with normal partial thromboplastin time (PTT) and low assay levels of FX, when measured by PT-based assay. They do not have clinical bleeding diathesis, regardless of the PT prolongation. FX genes of the affected family members were analyzed by sequence analysis. A novel missense mutation in exon 4 of the FX gene, which causes the Glu51Lys substitution in the first epidermal growth factor-like domain of FX was found. The Glu51Lys mutation represents a type II mutation with low FX coagulant activity in the extrinsic pathway and normal FX antigen levels. This mutation may result in disruption of the predicted H-bonding between residue Glu51 of FX and the Asn199 residue of the tissue factor (TF) in the FX/TF/factor VIIa ternary complex, producing the phenotype 'FX deficiency Riyadh', with prolonged PT and normal PTT.
authors: Haematology Department, Laboratories, King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia. akramhilali@yahoo.com
authors: Akram
authors: A
authors: Al-Hilali
authors: Karin
authors: K
authors: Wulff
authors: Hikmat
authors: H
authors: Abdel-Razeq
authors: Khalida Abu
authors: KA
authors: Saud
authors: Fateh
authors: F
authors: Al-Gaili
authors: Falko H
authors: FH
authors: Herrmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004252:DNA Mutational Analysis; D005091:Exons; D005170:Factor X / Q000235:genetics* / Q000378:metabolism; D005171:Factor X Deficiency / Q000097:blood / Q000235:genetics*; D005260:Female; D005838:Genotype; D018698:Glutamic Acid; D006801:Humans; D008239:Lysine; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D010314:Partial Thromboplastin Time; D010375:Pedigree; D010641:Phenotype; D011517:Prothrombin Time; D012529:Saudi Arabia
chemical_list: D018698:Glutamic Acid; D005170:Factor X; D008239:Lysine