Biomarkers capable of identifying patients at high risk of developing the commonest cause of progressive cognitive decline, Alzheimer’s disease (AD), pre-symptomatically exist [5] but are either expensive and only available in very few centers (e.g. amyloid Positron Emission Tomography) or are invasive (e.g. amyloid and tau testing in the cerebrospinal fluid) and not suitable for for screening at the interface between primary and specialist care patients [6]. The gene discussed is MAPT; the disease is Alzheimer disease.