In fact, Nrgn is used as a CSF biomarker for synapsis loss in Alzheimer disease (Lashley et al. 2018; Blennow and Zetterberg 2018a, b), and could be a marker for other diseases and pathological states (Yang et al. 2015; Bereczki et al. 2017). The gene discussed is NRGN; the disease is early-onset autosomal dominant Alzheimer disease.