A particular polymorphic variant of the CNR1 gene, featuring multiple Adenine-Adenine-Thymine (AAT) repeats and deemed to regulate the transcription of CB1 receptor, has been associated with different risks for depression in Parkinson disease patients [177] and a diagnostic cluster of schizophrenia [178,179], (for contrasting results, see [180]). Here, CNR1 is linked to schizophrenia.