CLOCK and schizophrenia: Close relatives of individuals with schizophrenia have also a high risk of developing personality disorders (paranoid, schizotypal) or psychiatric disorders (schizophrenia, schizoaffective disorders, schizophreniform disorder, brief psychotic disorder, unspecified psychotic disorder, unipolar depression), questioning the existence of genetic factors (such as single nucleotide polymorphisms in core circadian clock genes) shared by these psychiatric disorders [42].