M1R based therapeutics, such as KarXT, a coformulation of M1R agonist xanomeline and trospium, a peripheral muscarinic M2R antagonist that ameliorates non-target side effects of xanomeline, are showing promising results in clinical trials for the treatment of schizophrenia (Brannan et al., 2019). Here, CHRM1 is linked to schizophrenia.