Established diagnostic processes applied in sporadic AD such as lumbar puncture, for one considered rather invasive and therefore an unfavorable procedure as seen for case 5, further provide no detailed, region-specific information about tau accumulation in the brain, rendering tau PET imaging, specifically when using second-generation tau tracers with reduced off-target binding, a powerful tool for correlating pathology with clinical symptoms and tracking disease progression. The gene discussed is MAPT; the disease is Alzheimer disease.