The lack of reliable noninvasive diagnostic biomarkers of biliary atresia (BA) results in delayed diagnosis and worsened patient outcome. Circulating microRNAs (miRNAs) are a new class of noninvasive biomarkers with encouraging diagnostic utility. In this study we examined the ability of serum miRNAs to distinguish BA from other forms of neonatal hyperbilirubinemia. BA-specific serum miRNAs were identified using a microfluidic array platform and validated in a larger, independent sample set. The miR-200b/429 cluster was significantly increased in the sera of BA patients and has promising diagnostic clinical performance.

Biliary atresia is a pediatric liver disease of unknown underlying etiology, in which fibro-inflammatory destruction of the extrahepatic biliary system leads to obstructive cholestasis. MicroRNAs are a class of short (18–23 nucleotide), non-coding RNA molecules which act as negative regulators of target mRNA stability and translation. The importance of these molecules in normal and diseased liver has been demonstrated, but their potential role in the pathogenesis of biliary atresia has not been addressed. We have profiled changes in liver microRNA levels in an established mouse model of the disease, identified significantly altered transcripts, and defined the spatial expression patterns of selected microRNAs. Two of these, miR-29a/29b1 are up-regulated in experimental biliary atresia. Using antisense oligonucleotide-mediated inhibition in mice, we have delineated the full set of hepatic genes regulated by miR-29 and identified two mRNA targets of potential pathological relevance in experimental biliary atresia, Igf1 and Il1RAP. We have used reporter assays to confirm that Igf1 and Il1RAP are direct targets of miR-29.