Alzheimer's disease: genetic basis and amyloid imaging as endophenotype

To date, all known Alzheimer's disease genes influence amyloid beta (A beta). Imaging of A beta deposition in the human brain using positron emission tomography (PET) tracers as [C-11]Pittsburgh Compound B ([C-11]PiB) or [F-18]FDDNP offers the possibility of using cortical tracer binding as a quantitative endophenotype for genetic studies of late-onset Alzheimer's disease (AD). In this review we investigate the association between cerebral A beta burden, as measured by amyloid PET imaging, and different genetic risk factors involved in AD. Through a look at the major genetic risk factors for both early-onset familial and late-onset sporadic forms of AD, we discuss the possible role of amyloid PET imaging as an endophenotype in AD. Several PET studies confirmed the high heritability of amyloid load estimated by PET imaging and its association with the major genetic risk factors for early and late onset AD, suggesting that cerebral binding of these amyloid tracers could represent an useful trait for large-scale genetic studies of AD.