MicroRNA‐199a‐5p may be a diagnostic biomarker of primary ITP

Summary There is no diagnostic test for primary immune thrombocytopenia (ITP). Certain microRNAs have shown to have diagnostic potential in ITP. We validated 12 microRNAs identified from two previous studies to find a diagnostic biomarker. The study included two ITP cohorts ( n = 61) and healthy controls ( n = 28). The first ITP cohort involved 24 patients from the Prolong study, patients with newly diagnosed/persistent ITP (<1 year) treated with corticosteroids ± IVIG but relapsed/failed to respond. The second cohort comprised 37 patients from ITP biobank, Østfold Hospital, Norway, patients had different disease stages and therapies. Twelve microRNAs were measured: miR‐199a‐5p, miR‐33a‐5p, miR‐195‐5p, miR‐130a‐3p, miR‐144‐3p, miR‐146a‐5p, miR‐222‐3p, miR‐374b‐5p, miR‐486‐5p, miR‐1341‐5p, miR‐766‐3p and miR‐409‐3p. miR‐199a‐5p, miR‐33a‐5p, miR‐374b‐5p, miR‐146a‐5p and miR‐409‐3p were expressed differentially in the entire ITP cohort compared to controls; of those only miR‐199a‐5p showed good discriminative ability between ITP and controls with area under the curve (AUC) of 0.718 (95% CI: 0.599–0.836). In the Prolong cohort (ITP < 1 year), miR‐199a‐5p and miR‐374b‐5p showed very good discriminative ability between ITP and controls with AUC of 0.824 (0.708–0.940) and 0.806 (0.688–0.924) respectively. This study confirmed that miR‐199a‐5p has good discriminative ability between primary ITP and healthy controls, thus may be a diagnostic biomarker of ITP.