Down-regulation of miR-9∗ in the peripheral leukocytes of Huntington's disease patients

Background: Huntington's disease (HD), caused by expansion of a polyglutamine tract within HUNTINGTIN (HTT) protein, is an autosomal dominant neurodegenerative disease associated with a progressive neurodegeneration of striatum and cerebral cortex. Although a few studies have identified substantial microRNA (miRNA) alterations in central nervous tissues from HD patients, it will be more accessible to employ these molecular changes in peripheral tissues as biomarkers for HD. Methods: We examined the expression levels of 13 miRNAs (miR-1, mirR-9, miR-9∗, miR-10b, miR-29a, miR-29b, miR-124a, miR-132, miR-155, miR-196a, miR-196b, miR-330 and miR-615), 10 of which previously demonstrated alterations and 3 of which are potential regulators of differentially-expressed genes in brains of HD patients, in the peripheral leukocytes of 36 HD patients, 8 pre-symptomatic HD carriers and 28 healthy controls. Results: We found expression levels of miR-9∗was significantly lower in HD patients compared with those in healthy controls, while other miRNAs did not show significant difference between these two groups. However, there was no significant correlation between Unified Huntington's Disease Rating Scales (UHDRS) and levels of miR-9∗in peripheral leukocytes of HD patients. Conclusion: Our findings indicate the potential of miR-9∗in peripheral leukocyte as a signature of neurodegeneration in HD patients.