miR-302d-3p expression and genotype are associated with CMV replication after allogeneic haematopoietic stem cell transplantation.

Cytomegalovirus (CMV) reactivation is a common complication after allogeneic haematopoietic stem cell transplantation (HSCT). It occurs in over a third of alloHSCT recipients, and is a major source of post-transplant mortality. miRNAs are small non-coding RNA molecules that are important regulators of gene expression. They are often dysregulated during disease, including transplant-related complications. Due to their presence in all body fluids, they can be used as potential biomarkers. In this study, we performed miRNA profiling to find differentially expressed host miRNAs in serum that could be linked to CMV reactivation after HSCT. CMV reactivation was confirmed by detection of CMV DNA in serum. We identified two miRNAs, miR-302d-3p (p < 0.001) and miR-6721-5p (p = 0.018), as differentially expressed between day + 30 and + 90 after HSCT in patients with CMV reactivation. Of these, miR-302d-3p was confirmed as overexpressed on day + 30 in a verification analysis performed on an independent cohort of patients (p = 0.027). Furthermore, we analysed two genetic variants in the gene coding for miR-302d-3p. We found one of them, rs13136737, to be significantly associated with CMV reactivation (p = 0.015). In conclusion, our study showed that miR-302d-3p is dysregulated and that its genetic variant rs13136737 may be important in development of CMV reactivation after HSCT.