Of the five muscarinic receptor subtypes, designated M1R-M5R and encoded, respectively, by CHRM1-CHRM5, M3R/CHRM3 expression is increased in CRC, whereas M1R/CHRM1 expression is reduced (Cheng et al., 2017; Alizadeh et al., 2022). The gene discussed is CHRM1; the disease is colorectal carcinoma.