Platelet phenotype in children with ANKRD26-related thrombocytopenia

The mechanisms of hemorrhagic manifestations in patients with ANKRD26associated thrombocytopenia (ANKRD26-AT) are poorly understood. The aim of this work is to detect possible morpho-functional disorders of platelets in patients with mutations in the ANKRD26gene by flow cytometry with activation. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. 8 children aged from 1.5 to 15 years were examined. The platelet count ranged from 29 to 172 thousand/μl, with a median of 60 thousand/μl. The severity of hemorrhagic manifestations was assessed on a standardized scale (Pediatric Bleeding Questionnaire, PBQ) and it ranged from 0 to 5 points, with a median of 3.5 points. Platelet activation was performed with a CRP + TRAP mixture. Comparison was carried out with the results of examination of 26 apparently healthy children (control group, CG) aged 2 to 15 years. When compared with CG, patients showed an increase in platelet size (FSC; p= 0.018) and granularity (SSC; p< 0.001) after activation. In contrast to the CG, the correlation between FSC and SSC of platelets in patients was not significant (cor. = 0.55; p= 0.15). Patients showed a high, significant relationship between the number and FSC of platelets (cor. = –0.93; p< 0.001), as well as an increased density of CD42b (p < 0.001) and a decrease in the proportion of procoagulant platelets (p= 0.01) after activation. The revealed changes indicate violations of the mechanisms of activation and shape changes of platelets in patients with ANKRD26-AT.