FV Leiden Is A Mutation In The Gene Biology Essay


Patient 2 shows no abnormal results this suggests the patient has fv Leiden. Fv Leiden is a mutation in the gene for coagulation factor v that is associated with resistance to activated protein C. This mutation through autosomal recessive dominant inheritance makes the factors V and Va resistant to inactivation by a natural anticoagulant. The inactivation of FV Leiden is much slower than normal factor Va. This is why factor Leiden is a weak risk factor for venous thromboembolic events and is a rare mutation and therefore shows no abnormal results in patient 2. To test for FV Leiden an APC test is done. APC is an activated protein C. In people with FV Leiden the coagulation factor V cannot inactive normally by APC leading to a longer clotting time and abnormal blood clots. (1)

Patient 3's data corresponds well with the treatment of heparin. Heparin is a polymer made of carbohydrates. It is also a therapeutic anticoagulant. It forms complexes with anti thrombin and plasma protease inhibitors. Anti thrombin is a protein presented in blood that is a natural inhibitor of blood coagulation. These complexes inactivate the serine protease coagulation factor causing a prolongation in both pt and aPTT.(2) This prolongation is because thrombin is being inhibited this then prolongs the thrombin time and slows down the intrinsic pathway and leads to slow coagulation. This is shown with patient 3's data. Results show both PT and aPTT are above normal range and shows aPTT is prolonged more than PT. Heparin can bind to both anti thrombin and thrombin causing a conformational change. This binding to both proteins causes the interaction to be much faster causing a faster inhibition of thrombin time and slowing clotting. Data shows above normal range for thrombin time. (4)

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Haemophilia A is an x-linked recessive disorder with a deficiency in fVIII from the intrinsic pathway. A deficiency in this factor causes the intrinsic pathway to take longer. It is also the most common inherited coagulation disorder affecting 1 in 10,000 males and overall affects 80% of all haemophilias. Data shows only patient 4 shows to have abnormal results for fVIII. A result of 15 is shown in patient 4 this shows to be below normal range.Haemophila A is associated with a prolonged activated partial thromboplastin time (aPTT) in the clotting process this is also shown with patient 4's data.(2)

Both patient 1 and 5 show similar results that link to warfarin and VKOR mutation. Both in warfarin and VKOR mutation the prothrombin time (PT) and aPTT are both prolonged which decrease the synthesis of factors II, VII, IX, and X and produce abnormal form of all vitamin k dependant factors. The results of both patients follows this statement by showing abnormal results for both the PT and aPTT and also shows the factors VII, IX, and FX are below normal range. In both warfarin and vitamin k deficiency the thrombin time and platelet count remain normal this is also shown in both the patients. Warfarin is a vitamin k antagonist which promotes the carboxylation of glutamic acid residues of factor II, VII, IX and X. These vitamin k dependent proteins require vitamin k for their gla modification. By taking warfarin the clotting factor activity is reduced this can be seen in both patients 1 and 5. In both patients the factors II, VII, IX and X are showing abnormal results. It affects the post-translational modification of vitamin k dependent proteins and uses vitamin k to this modification. Vitamin k epoxide reductase (VKOR) is the target for warfarin. The main role of this enzyme is to convert vitamin k epoxide back to vitamin k. Both warfarin and VKOR inhibit the recycling of vitamin k therefore either patient could have warfarin poisoning or a VKOR mutation. (2)(4)(5)

Patient 6 shows an abnormal result of a higher bleeding time. Higher bleeding time is seen in patients with the treatment of aspirin. Aspirin prolongs the bleeding time causing a rise above normal range this is because it stops the platelets from sticking to the blood vessel. Patient 6 shows a value of 17 this is seen to be higher than normal range. Aspirin is also known as an antiplatelet drug. It inhibits the function of platelets by inhibiting cyclo-oxygenase and therefore reducing thromboxane A2 production. (3)

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Results of patient 9 show an abnormal value of fibrinogen. This is because dysfibrinogenaemia has defects in fibrinogen that affect the platelet function. In dysfibrinogenaemia both the PT and APTT are prolonged this can also be seen with the data of patient 9. Thrombin time is also taken into account patients with this have a prolonged thrombin time. Dysfibrinogenaemia is a rare autosomal dominant recessive disorder that affects factor VII, prothrombin, fV, fXIII. Data shows abnormal results for factor VII and prothrombin this is because there is a defect in these factors. Results also show factor IX and X being abnormal this is because they are down stream in the pathway and therefore have a knock out affect even though they don't have defect. Prothrombin gets converted to thrombin which converts to fibrinogen. The conversion to thrombin causes a prolonged thrombin time and to fibrinogen causes an abnormal result in the patient's data. Patients with this disease have an increased risk of thrombosis.

Haemophilia B is an x-linked recessive disorder in which there is a deficiency of factor IX a serine protease. The function of FVIII and FIX are directly linked this is because FVII is a cofactor for FIX both the deficiencies have similar symptoms. Haemophilia B accounts for 20% of all haemophilias and affects 1 in 40,000 males. Patients with this disorder have a prolonged coagulation time (APTT) and a decreased FIX activity this can be seen in patient 8's data. The levels of FIX below 50% result in prolonged aPTT. Results show 25% level of FIX showing a prolonged aPTT. (2)

Patient 7's data shows the patient has liver cirrhosis this is because patients with liver disease show a prolongation for both the aPTT and PT this can be seen in patient 7's data. Abnormalities in fibrinogen can also be seen in liver disease this is because fibrinogen is made in the liver. The symptoms of liver disease promote bleeding. (2) An abnormal bleeding time can be seen in patient 7's data. Cirrhosis is a condition where the liver breaks down and a scar tissue is formed. The breakdown of the liver causes a decrease in fibrinogen that is made in the liver. The decrease in fibrinogen causes a high Reptilase time as seen in data. Reptilase time is dependent on fibrinogen; it is used to study defects in fibrinogen.

Patient 10 shows a severe bleeding time and an abnormal platelet count this indicated the patients results match up with a condition called Bernard-soulier syndrome. Bernard-souiler syndrome is a rare autosomal recessive bleeding disorder. Results show a prolonged bleeding time. The low platelet count as seen with the results is due to a defect that arises from a deficiency of glycoprotein Ib-1X complex. In patients with this syndrome abnormal platelet sizes can be seen. (3)(2)