[Pedigree Analysis and Molecular Mechanism Study of Hereditary Glanzmann Thrombasthenia Caused by Compound Heterozygous Mutation of the ITGA2B Gene].

Objective: The phenotype and genotype of a pedigree with Glanzmann thrombasthenia caused by compound heterozygous mutation in the ITGA2B gene and its molecular pathogenesis were explored. Methods: The platelet aggregation rate of the proband and his family was detected by using a platelet aggregation test with adenosine diphosphate, collagen, epinephrine, arachidonic acid, and ristocetin. The expression levels of CD41 (αⅡb), CD61 (ß3), and CD42b (GPⅠb) on the platelet surface was detected by flow cytometry. Gene sequencing technology was used for the genetic identification of the family. RT-PCR was used in the detection of mRNA splicing, and qRT-PCR was used in detecting the relative mRNA level of the ITGA2B gene. Bioinformatics analysis was used to evaluate the pathogenicity of mutation sites and their effects on protein structure and function. The expressions of total αⅡb and ß3 in platelets were analyzed by Western blot. Results: Except ristocetin, the other four inducers could not induce platelet aggregation in the proband. Flow cytometry showed that the expression levels of αⅡb and ß3 were only 0.25% and 9.76%, respectively, on the platelet surface of the proband, whereas GPⅠb expression was relatively normal. The expression levels of glycoproteins in the other family members were almost normal. c.480C>G and c.2929C>T mutations were detected in the proband through gene sequencing. The c.480C>G mutation was inherited from his mother, and the c.2929C>T mutation was inherited from his father. The RT-PCR and sequencing results showed that the c.480C>G mutation caused mRNA splicing in the proband and his mother, resulting in the deletion of 99 bases in c.476G-574A (p.S160-S192). qRT-PCR showed that the c.2929C>T variant reduced the mRNA level of the ITGA2B gene in the proband and his father. Bioinformatics analysis suggested that the c.480C>G mutation might form a binding sequence with hnRNP A1 protein and generate the 5'SS splice site. The three-dimensional structural model of the αⅡb subunit showed that the ß-propeller domain of the p.S160-S192 deletion lost two ß-strands and one α-helix in blade 2. The c.2929C>T nonsense mutation caused premature translation termination and produced a truncated protein with the deletion of p.R977-E1039, including the cytoplasmic domain, transmembrane domain, and a ß chain of the extracellular Calf-2 domain. The total αⅡb expression of the proband was absent, and the relative expression of ß3 was 11.36% of the normal level. Conclusion: The compound heterozygous mutation c.480C>G in exon 4 and c.2929C>T in exon 28 of the ITGA2B gene probably underlies Glanzmann thrombasthenia in this pedigree.

An effective indicator in predicting cardiovascular events: urine albumin to creatinine ratio.

OBJECTIVE: To study elderly hypertensive patients with trace albuminuria (urine albumin to creatinine ratio (UACR)) and the relationship between the occurrence of new cardiovascular events, to provide a basis for early prevention in elderly patients with high blood pressure. PATIENTS AND METHODS: A total of 3564 elderly patients with high blood pressure were enrolled in the study. Based on UACR, patients were divided into four groups (group A: 0.05-3.20 mg/g; group B:3.21-10.04 mg/g; group C: 10.05-19.33 and group D: 19.34-30.00 mg/g). All patients underwent follow-up for an average period of 3.8 years. Four groups were compared for new cardiovascular events and they were correlated with UACR. RESULTS: Through multivariate Cox proportional hazards regression analysis, the relative risk of cardiocerebrovascular events, cerebral infarction, and acute myocardial infarction (mi), in group D was 1.74 times (p < 0.05), 1.66 times (p < 0.05), and 2.48 times (p < 0.05), respectively. UACR level in females and those with higher age, body mass index, systolic blood pressure, fasting blood glucose, TG, TC, LDL-C levels and lower HDL-C were higher. During follow-up, patients from group D with sudden cardiac death, acute myocardial infarction, cerebral hemorrhage, cerebral infarction occurrence was significantly higher than group A (χ2 = 79.3, p = 79.3) CONCLUSIONS: According to UACR level, we can perform early prevention for elderly patients with high blood pressure, thus reducing the occurrence of cerebral infarction and myocardial infarction.