Although mGluR5 expression in astrocytes declines postnatally (22, 23), previous works have shown an upregulation of this receptor in astrocytes in neurological diseases that most commonly affect adults or the elderly, such as amyotrophic lateral sclerosis (ALS) (24), multiple sclerosis (MS) (25), and Alzheimer’s disease (AD) (26), suggesting a relevant role of mGluR5 in gliopathology. Here, GRM5 is linked to early-onset autosomal dominant Alzheimer disease.