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BACKGROUND: The acquired inhibitors of coagulation have been observed in very rare cases of monoclonal gammopathies. We report a very rare case of anti-factor XI antibodies in patient with plasma cell leukemia (PCL). CASE PRESENTATION: This is a 59-year-old male patient without pathological history, admitted to the nephrology department for management of renal insufficiency and anemia syndrome. The history and physical examination revealed stigmata of hemorrhagic syndrome including hemothorax and hemoptysis. The hemostasis assessment showed an isolated prolonged activated partial thromboplastin time (APTT) with APTT ratio = 2.0.The index of circulating anticoagulant (37.2%) revealed the presence of circulating anticoagulants. The normalized dilute Russell viper venom time ratio of 0.99 has highlighted the absence of lupus anticoagulants. The coagulation factors assay objectified the decrease of the factor XI activity corrected by the addition of the control plasma confirming the presence of anti-factor XI autoantibodies. In addition, the blood count showed bicytopenia with non-regenerative normocytic normochromic anemia and thrombocytopenia. The blood smear demonstrated a plasma cell count of 49% (2842/mm3) evoking PCL. The bone marrow was invaded up to 90% by dystrophic plasma cells. The biochemical assessment suggested downstream renal and electrolyte disturbances from exuberant light chain production with abnormalities including hyperuricemia, hypercalcemia, elevated lactate dehydrogenase, non nephrotic-range proteinuria and high level of C reactive protein. The serum protein electrophoresis showed the presence of a monoclonal peak. The serum immunofixation test detects the presence of monoclonal free lambda light chains. He was treated with velcade, thalidomide and dexamethasone. The patient died after 2 weeks despite treatment. CONCLUSION: Both PCL and anti-factor XI inhibitors are two very rare entities. To the best of our knowledge, this is the first reported case of a factor XI inhibitor arising in the setting of PCL. Factor inhibitors should be suspected in patients whose monoclonal gammopathies are accompanied by bleeding manifestations.
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We investigated the impact of non-genetics factors, and single nucleotide polymorphisms (SNPs) in VKORC1, CYP2C9, CYP4F2, and GGCX on acenocoumarol dosage in Moroccan adult's patients, in order to develop an algorithm to predict acenocoumarol dose for Moroccan patients. Our study consisted of 217 Moroccan patients taking a maintenance dose of acenocoumarol for various indications. The patients were genotyped for VKORC1 -1639 G>A, VKORC1 1173 C>T, CYP2C9*2, CYP2C9*3, CYP4F2 1347 G>A and GGCX 12970 C>G SNPs. The statistical analysis was performed using the SPSS software. The age and SNPs in VKORC1 and CYP2C9 were significantly associated with the weekly acenocoumarol dose requirement (p = 0.023, p = 0.0001 and p = 0.001 respectively). There was no association found between the weekly acenocoumarol dose and the CYP4F2 or GGCX variants (p-value > 0.05). Non-parametric analysis confirmed the accumulate effect of variant alleles at VKORC1 -1639 G>A, VKORC1 1173 C>T and CYP2C9 SNPs on the acenocoumarol dose requirement. With 90.24% less dose required for one patient carrying homozygote variant at VKORC1 -1173 (TT) and CYP2C9 *x/*x haplotype. The multiple linear regression analysis showed that mutation in VKORC1 -1639, VKORC1 1173 SNPs, or in CYP2C9 haplotype reduces the mean acenocoumarol weekly dose to 25.4%, 23.4% and 6.2%, respectively. The R2 for multiple regression analysis final model was found to be 35.9%. In this work we were able to establish the factors influencing interindividual sensitivity to the anticoagulant therapy that can help physicians to predict optimal dose requirement for long term therapy.