Congenital vitamin K-dependent coagulation factor deficiency: a case report.
ABSTRACT Congenital vitamin K-dependent coagulation factor deficiency is a very rare bleeding disorder, which usually presents with episodes of intracerebral bleed in the first few weeks of life, sometimes leading to a fatal outcome. We report a case of combined factor deficiency of vitamin K-dependent factors in which the patient presented with both intracerebral bleeding, and possibly also thrombosis, and responded to a vitamin K supplement along with fresh frozen plasma.
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ABSTRACT: Hereditary combined deficiency of the vitamin K-dependent coagulation factors II, VII, IX, X, protein C, S and protein Z (VKCFD) is a very rare autosomal recessive inherited bleeding disorder. The phenotype may result from functional deficiency of either the gamma-glutamyl carboxylase (GGCX) or the vitamin K epoxide reductase (VKOR) complex. We report on the third case of VKCFD1 with mutations in the gamma-glutamyl carboxylase gene, which is remarkable because of compound heterozygosity. Two mutations were identified: a splice site mutation of exon 3 and a point mutation in exon 11, resulting in the replacement of arginine 485 by proline. Screening of 100 unrelated normal chromosomes by restriction fragment length polymorphism and denaturing high-performance liquid chromatography analysis excluded either mutation as a frequent polymorphism. Substitution of vitamin K could only partially normalize the levels of coagulation factors. It is suggested that the missense mutation affects either the propeptide binding site or the vitamin K binding site of GGCX.British Journal of Haematology 09/2004; 126(4):546-9. · 4.94 Impact Factor
Article: Four factor deficiency.[show abstract] [hide abstract]
ABSTRACT: Four factor deficiency is variably associated with mild to fatal bleeding. We describe a 3-month-old boy, born of consanguineous parents, who presented with a right subdural haematoma and a clotting screen showing a prothrombin time (PT) > 100 s, an activated partial thromboplastin time (aPTT) > 150 s, a fibrinogen of 0.4 g/l, and fibrinogen degradation products < 1 microg/ml. He was given 300 U of factor IX concentrate (containing factors II and X) and 1 mg of vitamin K intravenously. Forty-five minutes later, clotting tests showed a PT of 24 s, an aPTT of 31 s and a fibrinogen of 2.6 g/l. The patient was found to be deficient in all the vitamin K-dependent factors: factors II, VII, IX and X, protein C and protein S. A 14-base deletion was found in intron 1 (bases 1056-1069) of the gamma-carboxylase gene. The patient and his elder sister were homozygous for this deletion, whereas both parents were heterozygous. The deletion destroys a reverse palindromic sequence (TTGAGGCAA) of the type often associated with cis-acting elements. Our results suggest that this element may be involved in the regulation of gamma-carboxylase expression. Expression studies are being completed so that this region can be definitively ascribed as a cis-acting element involved in gene regulation.Blood Coagulation and Fibrinolysis 06/2003; 14 Suppl 1:S55-7. · 1.25 Impact Factor
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ABSTRACT: Coumarin derivatives such as warfarin represent the therapy of choice for the long-term treatment and prevention of thromboembolic events. Coumarins target blood coagulation by inhibiting the vitamin K epoxide reductase multiprotein complex (VKOR). This complex recycles vitamin K 2,3-epoxide to vitamin K hydroquinone, a cofactor that is essential for the post-translational gamma-carboxylation of several blood coagulation factors. Despite extensive efforts, the components of the VKOR complex have not been identified. The complex has been proposed to be involved in two heritable human diseases: combined deficiency of vitamin-K-dependent clotting factors type 2 (VKCFD2; Online Mendelian Inheritance in Man (OMIM) 607473), and resistance to coumarin-type anticoagulant drugs (warfarin resistance, WR; OMIM 122700). Here we identify, by using linkage information from three species, the gene vitamin K epoxide reductase complex subunit 1 (VKORC1), which encodes a small transmembrane protein of the endoplasmic reticulum. VKORC1 contains missense mutations in both human disorders and in a warfarin-resistant rat strain. Overexpression of wild-type VKORC1, but not VKORC1 carrying the VKCFD2 mutation, leads to a marked increase in VKOR activity, which is sensitive to warfarin inhibition.Nature 03/2004; 427(6974):537-41. · 38.60 Impact Factor