[Risk Factors of Multiple Myeloma Complicated with Venous Thromboembolism].

OBJECTIVE: To analyze the clinical characteristics of venous thromboembolism (VTE) in patients with multiple myeloma (MM) and to identify the risk factors of VTE in MM patients. METHODS: 179 newly diagnosed MM (NDMM) patients admitted to The Second Hospital of Shanxi Medical University from January 2014 to December 2020 who were followed up for more than 6 months were collected, and they were divided into VTE group and control group according to whether combined with VTE. The clinical and laboratory data were compared between the two groups. Mann-whitney U test was used for inter-group comparison of measurement data, Chi-square test or Fisher's exact test was used for inter-group comparison of count data, and multivariate logistic regression analysis was performed to explore the risk factors of VTE in MM patients. RESULTS: Compared with control group, the serum albumin (ALB) level in VTE group was significantly lower (P =0.033), the fibrinogen (FIB) level was significantly higher (P =0.016), and the proportion of patients with D-dimer≥2 000 ng/ml was significantly higher than that in the control group (26.3% vs 4.4%, P =0.002). There was a significant difference in M-component type between the two groups (P =0.028), and the proportion of IgG type in VTE group was higher. There were no statistically significant differences between two groups in age, sex, body mass index (BMI), the proportions of patients with hypertension, diabetes, coronary heart disease and cerebral infarction, white blood cell (WBC) count, platelet (PLT) count, liver and kidney function, plasma cells ratio in bone marrow, serum globulin (GLO), lactate dehydrogenase (LDH), ß2-microglobulin (ß2-MG) level, C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), prothrombin time (PT), activated partial thromboplastin time (APTT), disease stage, thrombosis prevention and the use of immunomodulators (P >0.05). Multivariate logistic regression analysis showed that FIB level (OR=1.578, 95%CI:1.035-2.407, P =0.034), D-dimer≥2 000 ng/ml (OR=5.467, 95%CI:1.265-23.621, P =0.023) and IgG type (OR=4.780, 95%CI: 1.221-18.712, P =0.025) were independent risk factors for VTE in MM patients. CONCLUSION: MM patients are prone to VTE, and FIB level, D-dimer≥2 000 ng/ ml and IgG type are independent risk factors for VTE in MM patients.

Molecular mechanism of a novel Ser362Asn mutation causing inherited FX deficiency in a Chinese family.

Factor X (FX) deficiency is an inherited autosomal recessive bleeding disorder. Here, we analyzed a proband with FX deficiency in a Chinese family. Genetic analysis revealed that the proband and his affected sister was homozygous for c.1085G>A mutation, corresponding to a Ser362Asn substitution. In vitro expression experiments showed that the FX Ser362Asn mutation led to a significant reduction in activity levels in the culture medium. This Ser to Asn substitution may change the shape of the active site. Moreover, simulations of molecular dynamics indicated that the binding energy of the FX Ser362Asn to the substrate is higher than that of wild type and the side-chain conformation of the catalytic residue His276 (His42) is changed. This impairs the conformational switch of the protein from zymogen to proteinase, thus causing the functional defect of FX protein. Our findings suggest that the Ser362Asn substitution is a pathogenic mutation that causes inherited FX deficiency.