Background To guide the neuroprotective management of infants with hypoxic ischaemic encephalopathy (HIE), early identification is essential. MicroRNAs are small non-coding RNA molecules with potential for use as biological markers for disease. The aim of this study was to investigate the expression profile of miRNA in umbilical cordblood (UCB) from infants with HIE.

Methods Full term infants with perinatal asphyxia (PA) were identified by a cord pH <7.1 and/or five minute Apgar score ≤ 6 and/or requirement for intubation/CPR at birth. Degree of encephalopathy was defined using both continuous multichannel-EEG in the first24 hours, and modified Sarnat score. In total, 70 infants, 52 cases (32 PA without HIE, 20 with HIE) and 18 controls, were included in the study. miRNA was extracted from UCB and the expression profiles of 866 miRNAs were determined using a microarray assay. Significant findings (fold change > ± 1.3) were validated using quantitative RT-PCR (qRT-PCR).

Results On microarray 70 miRNAs were differentially expressed between the HIE and the control group. Of these hsa-miR-374a was the most significantly downregulated in HIE vs controls (p < 0.001). Validation of expression using qRT-PCR confirmed a significant reduction in expression among HIE vs. perinatal asphyxia vs. controls (mean RQ (SD) = 0.5215 (0.374) vs 1.1022(1.521) vs 1.755 (1.689), p < 0.02).

Conclusion To our knowledge, this is the first study to describe the miRNA profile present in umbilical cord blood following HIE. Our results confirm the potential utility of miRNA biomarkers in the early diagnosis of HIE.