Clinical diagnosis and treatment of hereditary thrombocytopenia and purpura: a report of five cases and literature review / 中华血液学杂志

Objective: To report the clinical manifestations and laboratory features of five patients with congenital thrombotic thrombocytopenic purpura (cTTP) and explore its standardized clinical diagnosis and treatment along with a review of literature. Methods: Clinical data of patients, such as age of onset, disease manifestation, personal history, family history, and misdiagnosed disease, were collected. Treatment outcomes, therapeutic effects of plasma infusion, and organ function evaluation were observed. The relationship among the clinical manifestations, treatment outcomes, and ADAMTS13 gene mutation of patients with cTTP was analyzed. Additionally, detection of ADAMTS13 activity and analysis of ADAMTS13 gene mutation were explored. Results: The age of onset of cTTP was either in childhood or adulthood except in one case, which was at the age of 1. The primary manifestations were obvious thrombocytopenia, anemia, and different degrees of nervous system involvement. Most of the patients were initially suspected of having immune thrombocytopenia. Acute cTTP was induced by pregnancy and infection in two and one case, respectively. ADAMTS13 gene mutation was detected in all cases, and there was an inherent relationship between the mutation site, clinical manifestations, and degree of organ injury. Therapeutic or prophylactic plasma transfusion was effective for treating cTTP. Conclusions: The clinical manifestations of cTTP vary among individuals, resulting in frequent misdiagnosis that delays treatment. ADAMTS13 activity detection in plasma and ADAMTS13 gene mutation analysis are important bases to diagnose cTTP. Prophylactic plasma transfusion is vital to prevent the onset of the disease.

Effects of the ITGA2B Nonsense Mutation (c.2659C > T, p.Q887X) on Platelet Function in a Mouse Model of Glanzmann's Thrombasthenia Generated with CRISPR/Cas9 Technology / 中国实验血液学杂志

OBJECTIVE@#To construct a mouse model of Glanzmann's thrombasthenia (GT) with ITGA2B c.2659 C>T (p.Q887X) nonsense mutation by CRISPR/Cas9 technology, and then further explore the expression and function of glycoprotein αIIbβ3 on the surface of platelet membrane.@*METHODS@#The donor oligonucleotide and gRNA vector were designed and synthesized according to the ITGA2B gene sequence. The gRNA and Cas9 mRNA were injected into fertilized eggs with donor oligonucleotide and then sent back to the oviduct of surrogate mouse. Positive F0 mice were confirmed by PCR genotyping and sequence analysis after birth. The F1 generation of heterozygous GT mice were obtained by PCR and sequencing from F0 bred with WT mice, and then homozygous GT mice and WT mice were obtained by mating with each other. The phenotype of the model was then further verified by detecting tail hemorrhage time, saphenous vein bleeding time, platelet aggregation, expression and function of αIIbβ3 on the surface of platelet.@*RESULTS@#The bleeding time of GT mice was significantly longer than that of WT mice (P<0.01). Induced by collagen, thrombin, and adenosine diphosphate (ADP), platelet aggregation in GT mice was significantly inhibited (P<0.01, P<0.01, P<0.05). Flow cytometry analysis showed that the expression of αIIbβ3 on the platelet surface of GT mice decreased significantly compared with WT mice (P<0.01), and binding amounts of activated platelets to fibrinogen were significantly reduced after thrombin stimulation (P<0.01). The spreading area of platelet on fibrinogen in GT mice was significantly smaller than that in WT mice (P<0.05).@*CONCLUSION@#A GT mouse model with ITGA2B c.2659 C>T (p.Q887X) nonsense mutation has been established successfully by CRISPR/Cas9 technology. The aggregation function of platelet in this model is defective, which is consistent with GT performance.

Clinical observation of desmopressin in the treatment of 15 patients with DDAVP / 中华血液学杂志

Objective: To assess the significance of DDAVP use in the diagnosis and treatment of VWD. Methods: An analysis of 15 VWD cases who referred to Hematology Division of First affiliated Hospital of Soochow University and treated with DDAVP from March 2016 to August 2018 was conducted. Efficacy and treatment response of DDAVP were monitored by observations of changes in factor Ⅷ procoagulant (FⅧ∶C) and von Willebrand Factor (VWF) related indicators before and 2 h after DDAVP injection. Results: Of 15 cases with VWD, 7 males and 8 females with a median age of 23 (6-46) years, 7 of 9 type I VWD patients achieved complete response (CR) , 1 type 2A VWD case CR, 5 type 3 VWD ones no response (NR) . The VWF multimer analysis in 5 patients combined with other plasma VWF values were in accordance with the known diagnosis. Conclusions: DDAVP was effective in most type 1 patients, and ineffective in some type 2 and almost all type 3 cases. It was helpful for diagnosis and subsequent treatment planning.

The diagnostic value of PLASMIC score in the discrimination between thrombotic thrombocytopenic purpura and disseminated intravascular coagulation / 中华血液学杂志

Objective: PLASMIC score was evaluated its value in differential diagnosis between the patients with thrombotic thrombocytopenic purpura (TTP) and those with disseminated intravascular coagulation (DIC) . Method: Twenty-four patients with TTP and 41 cases with DIC were retrospectively analyzed in this study. The platelet count, average red blood cell volume, indirect bilirubin, creatinine and prothrombin time international normalised ratio were collected, and then PLASMIC scores were calculated. Results: According to the risk classification of PLASMIC score, three (12.5%) TTP patients had moderate risk, and the rest 21 (87.5%) cases had high risk. In DIC patients, 92.7% cases were in low risk group, 4.9% at moderate risk, and only one case had high risk. Of these 65 patients, the sensitivity and the specificity to TTP of the high risk of the scoring system were 87.5% and 97.6%, respectively. Conclusion: The patients with high risk of PLASMIC score correlated well with clinical TTP diagnosis. The scoring system showed to be an excellent diagnostic model to distinguish TTP patients from those with DIC.

Application of Next Generation Sequencing in Genetic Diagnosis of Hereditary Platelet Disorders - Review / 中国实验血液学杂志

Hereditary platelet disorders are a heterogeneous group of disorders characterized by abnormal number or function of platelets, sometimes even involving other systems apart from blood abnormalities. The great clinical and genetic heterogeneity makes the diagnosis and treatment of hereditary platelet disorders as a huge challenge for clinicians. At present, only a small number of patients have received a clear molecular diagnosis of hereditary platelet diseases, and a lot of pathogenic genetic variations still remain unknown. The popularity of next generation sequencing (NGS) promotes the development of individualized gene sequencing. Researchers have made great progress in the field of hemostasis and thrombosis using whole genome sequencing (WGS), whole exone sequencing (WES) and target gene sequencing (TGS). The development of NGS has not only promoted the individualized molecular diagnosis of hereditary platelet diseases, but also laid a solid foundation for gene therapy in the future. In this review, the new progress of the diagnosis of platelet-related diseases by using next generation sequencing techniques, is summarized.

Changes of ADAMTS13 activity and vWF antigen level in patients with acute myelogenous leukemia and their significance / 中国实验血液学杂志

This study was purposed to investigate the changes of von Willebrand factor cleaving protease (ADAMTS13) activity and vWF antigen level in patients with acute myelogenous leukemia (AML) before and after treatment and evaluate their clinical significance. Seventy-three AML patients were enrolled in this study, the sodium citrate anticoagulated plasma was collected before and after their induction chemotherapy. Fluorescence resonance energy transfer substrate vWF73 (FRETS-vWF73) assay was established to detect the plasma ADAMTS13 activity while vWF antigen level was measured by ELISA. The results showed that the ADAMTS13 activity in newly diagnosed patients with AML before induction therapy was obviously lower than that in normal controls (63.3 ± 25.5)% vs (105.1 ± 37.7)(P < 0.01), while the vWF antigen level was higher than that in normal controls (226.6 ± 127.0)% vs (111.4 ± 39.7)% (P < 0.01). After standard induction chemotherapy, the ADAMTS13 activity of AML patients in complete remission period was higher than that in AML patients before therapy (P < 0.01), and was not significant difference with that in normal controls; the vWF antigen was significantly lower than that in AML patients before therapy (P < 0.01), but it still was higher than that in controls (P < 0.05). The ADAMTS13 activity in newly diagnosed AML patients complicated with infection before therapy was obviously lower than that in AML patients without infection (52.2 ± 20.6)% vs (73.9 ± 24.7)% (P < 0.01), while the vWF antigen level was significantly higher than that in AML patients without infection (262.2 ± 135.7)% vs (193.8 ± 110.2)% (P < 0.05). The ADAMTS13 activity in AML patients with disseminated intravascular coagulation (DIC) was significantly lower than that in AML patients without DIC (42.0 ± 14.5)% vs (73.4 ± 22.7)% (P < 0.01), while the vWF antigen level was obviously higher that in AML patients without DIC (274.2 ± 140.0)% vs (204.7 ± 115.5)% (P < 0.01). It is concluded that the ADAMTS13 activity in newly diagnosed AML patients befor induction therapy has been confiremed to be lower and the vWF antigen level to be higher, especially in AML patients with infection or DIC. The ADAMTS13 and vWF antigen may play a role in the pathogenesis of AML and the formation of infection and DIC.

Identification and functional analysis of a novel missense mutation Ser250Phe underlying congenital coagulation factor Ⅶ deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify and characterize a missence mutation Ser250 Phe underlying coagulation factor Ⅶ (FⅦ) deficiency in a Chinese patient and his family.</p><p><b>METHODS</b>The FⅦ gene (F7) was analyzed by DNA sequencing, and the FⅦ levels (including antigen and activity) in patient's plasma were determined with enzyme-linked immunoabsorbent assay (ELISA) and one stage prothrombin time based method. In addition, a FⅦ-250 Phe mutant corresponding to the identified mutation was expressed in HEK293 cells, and a subcellular localization experiment in CHO cells was performed to clarify the molecular mechanism of FⅦ deficiency caused by the FⅦ-250 Phe mutation.</p><p><b>RESULTS</b>The patient had a prolonged prothrombin time (PT: 36.5 s) and low levels of both FⅦ antigen and activity (130.2 ng/mL and 4.0%, respectively). Two heterozygous mutations were identified in the F7 gene (NG-009262.1), which included a g.15975 G>A mutation at the splice receptor site of intron 6 (IVS6-1G>A) and a novel g.16750 C>T mutation in exon 8, which resulted in replacement of Ser (TCC) 250 with Phe (TTC)250 in the vicinity of a charge-stablizing system. By gene expression experiments, the antigen and activity levels of FⅦ-250 Ser and FⅦ-250 Phe in the culture medium were (37.77 ± 2.30) ng/mL and (4.02 ± 0.52) ng/mL, respectively. ELISA and Western blotting analyses indicated that expression of the mutant FⅦ-250 Phe and wild type FⅦ-250 Ser was (130.51 ± 2.32) ng/mL and (172.45 ± 2.25) ng/mL, respectively. FⅦ-250 Phe was found in endoplasmic reticulum and Golgi apparatus, suggesting that the mutant FⅦ-250 Phe could be normally synthesized in the cells but was inefficiently secreted.</p><p><b>CONCLUSION</b>Compound heterozygous mutations in F7 gene (g.15975G>A and g.16750C>T) may be responsible for the FⅦ deficiency in this patient. The novel FⅦ 250 Phe can be transported from endoplasmic reticulum to Golgi apparatus, but may be degraded or inefficient.</p>

Congenital afibrinogenemia caused by a novel insertion mutation in the FGB gene / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the genetic defect and its mechanism in a patient with congenital afibrinogenemia.</p><p><b>METHODS</b>The plasma fibrinogen activity and antigen of the patient was determined using the Clauss method and immuno-nephelometric assay, respectively. Genomic DNA was isolated from peripheral blood of the proband and his related family members. All exons and exon-intron boundaries of the three fibrinogen genes (FGA, FGB, FGG) were amplified by PCR followed by direct sequencing. Thrombin fibrin aggregation curve were detected in the plasma of the patient. Wild-type and mutation type fibrinogen vectors were constructed, and then transfected into COS-7 cells. The wild-type and mutant proteins from the culture media and cell lysates were tested by Western blot and ELISA.</p><p><b>RESULTS</b>APTT, PT, TT were significantly longer in the proband. Plasma fibrinogen activity and antigen of the patient could not be detected using the Clauss method and immuno-nephelometry, respectively. Gene analysis revealed that a novel homozygous GTTT insertion between nucleotides 2833 and 2834 in FGB exon 2 in the proband. The proband's father, mother, brother and son were heterozygous. The polymerization curves of the patient did not show a lag phase or final turbidity, compared with the normal controls. Western blot analysis showed the lack of complete half-molecules of the fibrinogen molecule and fibrinogen in patient's plasma under non-reducing conditions. It also could not detect the truncated Bβ chain under reducing conditions. Abnormal fibrinogen molecule (molecule weight>340 000) were found in transfected COS-7 cells by Western blot, which indicated that the mutation caused the abnormal intracellular fibrinogen molecule assembly. The fibrinogen band was absent in culture media transfected by the mutation. Fibrinogen levels of mutant fibrinogen were no significant different from those of wild-type fibrinogen in cell lysates by ELISA analysis [(2.47 ± 0.30) μg/ml vs (2.65±0.60) μg/ml, P=0.0889]; However, the levels of the mutant fibrinogen were statistically significant lower than those of wild type fibrinogen in culture media [(0.01 ± 0.01) μg/ml vs (3.80±0.80) μg/ml, P=0.0001].</p><p><b>CONCLUSION</b>Congenital afibrinogenemia was caused by this frameshift mutation in exon 2 of FGB. This novel mutation impaired fibrinogen assembly and secretion.</p>

Clinical features and gene analyses of six patients with MYH9-related disease / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate clinical features and to identify gene mutations in six patients with nonmuscle myosin heavy chain 9 gene (MYH9)-related disease.</p><p><b>METHODS</b>The platelet counts were measured using automated complete blood cell counter and manual manner. The size of platelets and inclusion bodies were observed under light microscopy. All the 40 exons and exon-intron boundaries of MYH9 gene were amplified by PCR and then DNA sequencing was performed. Restriction endonuclease analysis and polyacrylamide gel electrophoresis (PAGE) were used for polymorphism analysis.</p><p><b>RESULTS</b>Six patients all shared the common features of thrombocytopenia with giant platelets and granulocyte inclusions. Four MYH9 gene mutations were found in the six patients: T97C (W33R) in exon 1, 4335Insert CAGAAGAAG (1445InsQKK) and G4269A (D1424N) in exon 30 and G5833T (E1945Stop) in exon 40. The former two were novel mutations which have not been reported in the literature. The results of restriction endonuclease analysis and PAGE could exclude the possibility of nucleotide polymorphisms.</p><p><b>CONCLUSIONS</b>The MYH9 gene mutations were identified in six patients with MYH9 related disorders, and T97C (W33R) and 4335InsCAGAAGAAG (1445InsQKK) were novel mutations. MYH9 related disease should be considered in individuals with persistent thrombocytopenia which is non-responsive to corticosteroids and immuno-repressive agents.</p>

In vitro effects of hemocoagulase atrix and its effective components on blood coagulation of patients with bleeding disorders / 中国实验血液学杂志

This study was aimed to investigate the pro coagulation effects of hemocoagulase atrix and its effective components (batroxobin and factor X activator) on plasma of normal subjects and patients with bleeding disorders and their mechanisms. Activated partial thromboplastin time (APTT) and prothrombin time (PT) were measured. The factor (F)X activation and thrombin generation were analyzed by using chromogenic substrate method. The results showed that the plasma APTT of normal subjects was shortened by hemocoagulase atrix, batroxobin and FX activator, and the effect of FX activator was found to be concentration-dependent (r = 0.889, P < 0.05). The prolonged APTT of plasma from patients with bleeding disorders could be corrected by hemocoagulase atrix, batroxobin and FX activator, but PT showed no great changes resulted from the treatments. FX activator could promote FX activation and thrombin generation, while neither hemocoagulase atrix nor batroxobin showed such abilities. It is concluded that hemocoagulase atrix promotes coagulation process, and corrects coagulation abnormalities in patients with bleeding disorders, its main component batroxobin directly acts on fibrinogen, and FX activator promotes thrombin generation through activating FX.