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Case Study: Understanding the Effects of Hemophilia C
Hazem Elkhaleegy, Chairman Professor of Clinical Pathology, Faculty of Medicine, Al-Azhar University
16 January 2017
Hemophilia C (Para hemophilia) is an inherited autosomal recessive disorder characterised by the low level of FXI (Factor XI). FXI deficiency was first described by Rosenthal el al in 1953 and described it as a new type of hemophilia i.e. Hemophilia C. The highest prevalence of this disease was observed in patients from English, African- American, Indian, German, Korean, Japanese, Portuguese, Arab and Iranian origins. A 25-year-old girl with history of prolonged aPTT was analyzed and tested by using Factor deficient plasmas (FVIII, IX, XI and XII). She was found to be having low levels of FXI. Percentage activity of FXI was found to be 45.6% of normal.
A 25-year-old female, Sri Lankan in origin was presented in emergency to Al Qurayat General hospital, with a complain of low back pain. She was diagnosed as a case of renal calculus and lithotripsy was planned. Her blood sample was sent to Central laboratory of Al Qurayat General hospital for routine blood tests. Her aPTT (activated partial thromboplastin time) was found prolonged and procedure was delayed to rule out the cause for prolonged aPTT.
The patient presented with a complain of right lumber region pain for last two months along with burning micturition. She also complained of gross hematuria three days back. There was history of nosebleed (epistaxis) two weeks back. The patient also complained of mild bleeding from gums every now and then during the process of cleaning teeth for a long period of time. The age of menarche was 13 years and the patient experienced irregular menstruation since the age of 16 with alterative periods of amenorrhea and Menorrhagia. The patient also complained of changing 4-6 pads per day. Patient also complained of joint swelling after excessive walk when back in Sri Lanka. The most common joints involved were reported as knee joints followed by ankle joints. Patient has history of appendectomy in Sri Lanka. There is no history of excessive blood loss during the operation. There is no history of bruising. No history of smoking. Alcohol and drug abuse was reported. The patient has two siblings who are in good health without such sign and symptoms.
On general physical examination no petechiae and bruising was observed. Liver, spleen and lymph nodes were found to be normal. No other skeletal abnormality was found.
MATERIAL AND METHODS
Principle of the method
Plasma deficient in any of the factors comprising the intrinsic pathway will result in a prolonged partial thromboplastin time (APTT). Coagulation factor deficient plasma can be used to confirm a factor deficiency, in general, and to identify the coagulation factor in patient plasma. A mixture of the respective factor deficient plasma and the patient plasma is tested in the APTT assay. Patient plasma deficient in the specific factor will not be able to compensate for the absence of the factor in the corresponding coagulation factor deficient plasma and therefore result in the prolonged APTT.
Materials Used - Factor VIII, IX, XI and XII deficient plasma; APTT reagent; Calcium chloride solution.
Coagulation factor deficient plasmas are lyophilized human plasmas with a residual factor VIII, IX, XI and XII activity <1. The deficient plasmas are manufactured by immunoadsorption from normal plasma and are free from antigen of respective factor. Fibrinogen is present at a quantity of at least 1g/L and the remaining coagulation factors are present in an activity greater than 40% of the normal. The plasma contains mannitol 20g/L as a stabilizer.
PREPARATION OF THE REAGENTS
Deficient plasmas: We dissolved the contents of vial with 1ml of distilled or deionized water. Before use we let it stand for at least 15 minutes at 15-25C, swivelled carefully to mix and avoided the foam formation.
The sample of the patient was received in citrated vial. The test for Prothrombin time (PT) and activated partial thromboplastin time was performed by using Stago ST Art. The mixing study was done and the value for aPTT after correction was found to be 42.7seconds..
Patient’s sample was then tested with Factor VIII, IX, XI and XII deficient plasmas, LA1 and LA2 antibodies.
Hemophilia C is a rare inherited autosomal recessive disorder characterised by the low level of FXI in the blood. FXI has a pivotal role in coagulation pathway, after activated by thrombin can bypass initial contact reactions. FXI also plays an important role in generating the thrombin following its initial formation by the tissue factor-factor VII pathway.
This patient had a history of chronic raised aPTT with some associated clinical problems such as on and off nose bleeds, bleeding from the gums which occurred most often while cleaning the teeth, Menorrhagia followed by amenorrhea since the onset of menarche, hemarthrosis which the patient often experienced after a long walk. There is also history of hematuria after the patient diagnosed as having renal calculus.
Coagulation factor studies were done in the Central Laboratory of Al Qurayyat General hospital to rule out the cause of prolonged aPTT. Initially aPTT was found grossly prolonged and was found to be 88.6 sec against the normal control aPTT of 32.3 sec. To find out this prolongation in aPTT is due the clotting actor deficiency or due to the presence of an inhibitor mixing study was done by mixing patient plasma with normal plasma in the ratio of 50/50. The result which we obtained was 37.5 sec. This result excluded the presence of any inhibitor and suggested that there is any intrinsic factor deficiency.
For the purpose of finding the exact coagulation factor of which the patient is deficient of we tested patient’s plasma with Factor VIII, IX, XI, XII deficient plasmas. The aPTT was found to be in near normal range with all the factors except FXI.
The percentage normal activity of the factors was calculated by testing the Factor deficient plasmas with the normal plasma. % activity of FXI in patient plasma was calculated as 45.6%. Thus the patient is found to be having less than 50% activity of normal FXI.
References available on request