NRXN2 and schizophrenia: However, several of the mapped genes at the chronotype-associated loci are well-known schizophrenia loci such as NRXN1 (as well at NRXN2 and NRXN3) and RELN39,40 and subsequent studies will be necessary to understand the shared biological mechanisms between chronotype and schizophrenia risk.