Cystatin is a small molecular weight protein and is typically used as a marker of renal function, but higher levels have also been linked to the development of late‐onset Alzheimer's Disease (Chuo et al., 2007) and it has been implicated in diverse aspects of immunity/inflammation and apoptosis (Zi & Xu, 2018). The gene discussed is CST4; the disease is late-onset Alzheimers disease.