As we have previously carried out several successful case-control association studies between schizophrenia and SNP’s in OPRM1, DRD3, SNAP-25, MTHFR and ADRA2A genes in samples of typical European population [14-16] we decided to use a similar approach to test the present hypothesis and include both CTXN3 and DISC1 gene polymorphisms in our investigation. The gene discussed is CTXN3; the disease is schizophrenia.