Concordance between platelet counts by impedance and optical technique during microcytic anemia: towards a threshold value of the mean corpuscular volume.

INTRODUCTION: Platelet count is crucial for clinical decision. In cases of microcytosis, platelet count based on impedance technique (PLT-I) may overestimate platelet count. AIM: To compare PLT-I with platelet count using the optical technique (PLT-O) and establish a Mean Corpuscular Volume (MCV) threshold for considering PLT-O. METHODS: A prospective analytical study conducted over two months involved blood samples collected in standard K2 EDTA tubes for complete blood count analysis, revealing microcytosis (MCV<80 fL). PLT-O analysis in channel-Ret mode was performed using the Sysmex-XN1000 (Sysmex Corporation, Kobe, Japan). Percentage of fragmented red cells (FRC%) and percentage of microcytic red cells (Micro-R%) were recorded. Blood smears stained with May-Grünwald-Giemsa were examined for potential interfering particles. RESULTS: A strong correlation was observed between the two techniques for all platelet values as well as for PLT <150 x 109/L (correlation coefficient r = 0.971, 95% CI: [0.956-0.982]; P<10-3 and r = 0.90, 95% CI: [0.79-0.95]; P< 10-3). The Bland-Altman plot revealed a bias of 16.53 x 109/L between the two methods, with agreement limits between -55.8 and 88.8 x 109/L. A threshold MCV value indicating the use of the optical method, with a cut-off at 72.9fL, demonstrated promising performance consistent with literature findings. However, less favorable performance was observed with Micro-R%. CONCLUSION: Impedance could be employed in routine practice. However, for MCV<72.9 fL or in the presence of schizocytes, the hemogram validation procedure may incorporate the use of PLT-O.

TP53 Gene 72 Arg/Pro (rs1042522) single nucleotide polymorphism increases the risk and the severity of chronic lymphocytic leukemia.

Background: Genetic variations in TP53 gene are known to be important in chronic lymphocytic leukemia (CLL) and may cause its inactivation which is associated with an aggressive form of the disease. Single nucleotide polymorphism (rs1042522:G>C) in TP53 gene at codon 72 encodes for arginine (Arg) or proline (Pro) variant which results in amino acid substitution affecting the apoptotic potential of TP53 protein. The aim of this study was to assess the correlation between TP53 codon 72 polymorphism and risk susceptibility as well as severity of CLL among Tunisian patients. Materials and methods: A case-control study was conducted in Tunisia from February 2019 to November 2021, 160 de novo CLL patients and 160 healthy volunteers matched in age and gender were involved. DNA was extracted from peripheral blood mononuclear cells and the rs1042522 was analyzed using PCR-RFLP. Results: Pro variant was associated with higher susceptibility to CLL than Arg variant (p= 0.023). A significant association was found between Pro variant and prognostic classification of Binet stage C (p= 0.001), low hemoglobin level (p= 0.003) and low platelet count (p= 0.016). Conclusion: We suggest that Pro variant may increase the risk of developing CLL in our population and could be associated with the severity of the disease.

The hypercoagulable state in multiple myeloma: The contribution of thrombin generation test.

BACKGROUND: Multiple myeloma is a hematologic malignancy which confers a high venous thromboembolic risk. This risk is linked to patient-related factors, disease-specific mechanisms, and antimyeloma therapy, especially immunomodulatory drugs. Some studies have suggested that the thrombin generation assay may be a predictive marker of thrombosis. This study aimed to assess the hypercoagulable state in patients with multiple myeloma at diagnosis and after myeloma therapy. METHODS: Thirty-one patients with multiple myeloma were included in a prospective study and were compared with 31 matched controls with age and gender. Thrombin generation assay was performed in patients at diagnosis prior to treatment initiation and at the end of myeloma therapy, and in controls. Parameters of lag time, peak thrombin concentration, time to peak, endogenous thrombin potential, and velocity index were analyzed. RESULTS: Median age of patients at diagnosis was 58 years (11 men and 20 women). Twenty-three patients (74%) were classified as high vascular risk and received thromboprophylaxis. No thromboembolic events have been reported during follow-up, except a symptomatic pulmonary embolism in one patient which occurred at diagnosis. At baseline, patients with myeloma had significantly elevated velocity index as compared to controls (178 vs 128 nmol/L/min; P = .013). High-risk patients showed an elevation of plasma thrombin generation as compared to low-risk patients (endogenous thrombin potential = 1244 vs 1052 nmol/L/min; P = .043). Myeloma therapy did not significantly change the thrombin generation parameters. CONCLUSION: Thrombin generation appears to be higher in patients with myeloma compared with controls, especially in high-risk patients, and does not change significantly after treatment completion.