Other studies found immunohistochemical positivity for complement factors C3d/C3b and C4d in Lewy bodies in the substantia nigra (Yamada et al. 1992; Loeffler et al. 2006), and an increase in C3 complement in AD and animal models (Wu et al. 2019; Bourel et al. 2021). The gene discussed is C3; the disease is Alzheimer disease.