PTK7 and Alzheimer disease: Advances in the identification of important biomarkers in different diseases, such as the overexpression of the transmembrane protein tyrosine kinase-7 (PTK7) in T cells in acute lymphoblastic leukaemia [97,98,99], the platelet-derived growth factor (PDGF) in the diagnosis of different types of tumours [100], and the proteins fetuin A and fetuin B present at low concentrations in the blood of individuals with Alzheimer’s disease (in contrast to high levels of clustering [101]), among many other markers and diseases, have allowed for the design of diagnostic strategies based on MNPs [97,102].