In addition, some studies have suggested that plasma levels of Aβ42 and Aβ40 are associated with the levels of cerebral Aβ on positron emission tomography (PET), cerebrospinal fluid levels of Aβ and tau, and AD-like brain atrophy [4], [7], [8], [11], [16], [17], [24], [31], [32], [33], [34], [35], [36], [37], [38], while others have not seen such an association [25], [39], [40]. The gene discussed is MAPT; the disease is Alzheimer disease.