Objective: In this pilot study we evaluated  serum mir-30c levels in MSA and  PD patients, to assess if mir-30c can be useful to distinguish these disorders.  Moreover, for the first time we assessed mir-30c levels in serum samples stored at -20°C.

Background: Diagnosis of MSA is mainly based  on clinical features and due to the overlapping clinical presentation, it can be difficult to distinguish MSA from PD and other parkinsonian disorders. Early differentiation between MSA and PD has clinical, therapeutic and prognostic consequences and may be difficult, if based solely on clinical examination (1.2). No reliable biomarker currently exists for the diagnosis and prognosis of MSA. MiRNAs are small noncoding RNAs with a key role in post-transcriptional gene regulation.  Recent studies have revealed that some miRNAs are differentially expressed in human brain and regulate the expression of genes associated with specific neurodegenerative disorders such as PD. However, several miRNAs are differently expressed in plasma and serum samples of MSA patients compared to PD and controls (1.2). Recently, we observed that miR-30c was downregulated only in PD patients compared to healthy controls (2).

Methods: We enrolled 24 patients with PD (60 ± 8 years) and 15 patients with MSA (65± 7 years). miRNAs were extracted from 200 μl of serum samples stored at -20°C using total RNA purification kit (Norgen Biotek Corp) and finally eluted in 50 μl volume of elution buffer. Mir-30c was quantified using miRcury LNA  assay (Exiqon) and expression fold changes were calculated by the 2−ΔΔCT method.

Results: Using miRcury LNA  assay, we analyzed serum mir-30c in PD and MSA samples. We confirmed that mir-30c was upregulated in PD compared to MSA patients with a fold change of 4.4. Moreover, for the first time we observed that levels of  mir-30c of the biobanked sera stored at -20°C were comparable to the profile of <1 year-old sera stored at -80°C.

Conclusions: Our results suggest that serum mir-30c could discriminate PD from MSA patients and be used as specific, non-invasive biomarkers for early diagnosis. Future prospective trials on large cohorts are warranted to confirm whether this miRNAs can be effectively used for early MSA diagnosis. Finally,our  pilot study suggests that circulating miRNAs retain their integrity under long-term sub-optimal storage temperatures opening the way for increased miRNA analyses in MSA and PD.

References: 1.Ubhi K. et al., (2014) Widespread microRNA dysregulation in multiple system atrophy – disease-related alteration in miR-96. Eur. J. Neurosci. 39, 1026–1041.

2.Vallelunga A. et al., (2014). Identification of circulating microRNAs for the differential diagnosis of Parkinson’s disease and Multiple System Atrophy. Front. Cell. Neurosci. 8, 156.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/serum-mir-30c-as-a-potential-biomarker-to-discriminate-msa-from-pd-patients-a-pilot-study/