TUG1 and Alzheimer disease: Therefore, the biological sample chosen for the analysis, the pharmacological treatment, the stage of the disease, and the age and sex of the patients can result in different observations, as seen for the TUG1 level in MS, which was found to be high in serum and PB but low in PBMC, and for LINC00507, which exhibited decreased expression in AD brains but an increased abundance in mouse and cellular models of AD (Table 1).