Blood RNA profiles could assist TIA diagnosis
MedWire News: Analyzing total RNA expression in the blood of patients with transient ischemic attack (TIA) may yield useful information on etiology and even risk for stroke, say researchers who found distinct expression profiles in patients compared with controls.
Patients had upregulated expression of genes associated with systemic inflammation, platelet activation, and prothrombin activation, report Xinhua Zhan (University of California at Davis, USA) and colleagues.
The team collected blood samples from 26 patients at an average of 35 hours after TIA symptom onset and from 26 control individuals who were matched for vascular risk factors, namely, hypertension, diabetes, hyperlipidemia, and current smoking.
As reported in the journal Neurology, 480 probe sets (corresponding to 449 genes) had different expression levels between patients and controls, with 129 being downregulated in patients and 351 upregulated.
Zhan et al narrowed this down to 34 probe sets that distinguished patients from controls with 100% sensitivity and specificity. In other words, all TIAs were identified and none were missed.
Besides the distinction between patients and controls, there were also two distinct RNA expression profiles within the patient group. There were no differences between these two patient subgroups with respect to age, gender, race, time since TIA, vascular risk factors, history of stroke, stroke risk, large vessel disease, lesions on imaging, and medications. However, the team stresses that the small numbers of patients in these groups limited the chances of detecting differences between them.
One of the subgroups, with 13 patients, had expression of significantly more genes associated with atherosclerosis, stroke, coronary artery disease, hypertension, and diabetes, compared with the other group.
The researchers note that all three patients with cerebral lesions on imaging and the one patient who had a stroke within 90 days of TIA were in the former group, but also observe that the other group could have contained patients with nonvascular conditions mimicking TIA.
In an accompanying editorial, Brett Cucchiara (University of Pennsylvania, Philadelphia, USA) and Paul Nyquist (Johns Hopkins School of Medicine, Baltimore, Maryland, USA) focused on the diagnostic and prognostic potential of the technique.
However, they noted that different assays would need to be developed, as "analysis of gene expression using microarrays is complex and time-consuming, and cannot be performed quickly and cost-effectively in a manner that would allow clinical use."
The editorialists concluded: "The results of Zhan et al give reason for hope, but also suggest that the path forward will be long, complex, and challenging."
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By Eleanor McDermid