Cerebrospinal fluid (CSF) studies are necessary in neurological diseases, but the use of healthy controls (HC) is limited due to the ethical issues and difficulty in obtaining them. Usually, the control group corresponds to patients with other neurological diseases (OND).
The main objective of this study was to evaluate the role of the control group in detecting altered miRNAs in multiple sclerosis (MS).
A panel of 216 CSF-specific miRNAs were analyzed using TaqMan Open Array Human Advanced MicroRNA in a cohort of 38 patients (16 primary progressive forms – PPMS, 9 HC, 13 OND).
HC corresponds to neurologically healthy patients with hip/knee impairment undergoing surgical intervention that requires spinal anaesthesia.
The pathologies presented by OND were: 6 individuals of vascular origin, 3 migraines, 1 conversion syndrome, 1 dementia, 1 dizziness, 1 cerebellar syndrome of non-inflammatory/infectious origin.
miR-1260a, miR-320a, and let-7c-5p showed differential expression, or a trend, in PPMS versus HC (p = 0.005; p = 0.021; p = 0.088, respectively). When making the same comparison with OND these significances were lost.
When analyzing deregulated miRNAs function, it was observed that let-7c-5p and miR-320a are involved in cerebral ischaemic and neurodegenerative disorders.
Choosing the control group is crucial to identify altered miRNAs in a specific condition. If the objective is to identify metabolic pathways involved in a certain process, HC will be necessary since OND controls can share the altered pathways. On the other hand, when the objective is to identify biomarkers, the incorporation of OND into the analysis will be of great value to differentiate pathologies.