81 Chapter 4 Platelet function was tested on an automated platelet function analyser (PFA-100; Siemens Healthcare Nederland B.V. Den Haag, the Netherlands). It measures the ability of platelets to adhere and aggregate under high shear stress to a membrane covered with collagen and epinephrine or collagen and ADP. Fibrinolysis was determined by semi-automated thromboelastometry (ROTEM delta; Werfen Netherlands, Breda, the Netherlands), which was locally calibrated as per the verification guidelines 22–24. Clot formation and lysis was determined after addition of reagents activating the internal or external coagulation pathway. Maximum lysis (ML) was optically measured as the percentage reduction of clot firmness within 60 min. Other Rotem parameters, such as clotting time (CT), clot formation time (CFT) and maximum clot firmness (MCF) all fell within the reference ranges (Table 1) and are therefore not further discussed. DNA was extracted from blood or saliva. Next-generation sequencing was performed for a panel of genes in which pathogenic variants are known to cause OI (ALPL, BMP1, COL1A1/2, CREB3L1, CRTAP, FKBP10, IFITM5, P3H1, LRP5, PLOD2, PLS3, PPIB, SERPINF1, SERPINH1, SP7, TAPT1, TMEM38B, WNT1). Identified pathogenic variants have been reported according to the Human Genome Variation Society guidelines for the nomenclature of DNA sequence variants 25. Statistical analyses Variables were tested for normal distribution with the Kolmogorov-Smirnov test. Means and standard deviation were given for normally distributed continuous variables. Nonnormally distributed continuous variables were presented as median, interquartile range (IQR), and categorical variables as frequencies (percentages). Differences in means comparing OI patients with the controls were tested using independent sample t tests and the mean differences were presented as the mean with 95% confidence intervals (95% CI). A two-sided P-value of 0.05 was considered significant. Analyses were performed using SPSS 25 for Windows (IBM Corp., Armonk, NY).
RkJQdWJsaXNoZXIy MTk4NDMw