Resequencing and follow-up of neurexin 1 (NRXN1) in schizophrenia patients.

Large rare deletions in NRXN1 increase the risk for schizophrenia. The aim of the present study was to determine whether small rare sequence changes in exons and splice sites contribute to the development of schizophrenia in a high-penetrance manner. Complete coding regions and splice sites were resequenced in 94 patients and 94 controls. Among the 16 rare sequence variants, two missense substitutions (E201G and I1068V) were observed in single patients but not in controls. Investigation of DNA samples from family members and in silico analysis of possible effects on protein function produced no evidence of high-penetrance genetic effects. Follow-up genotyping of the most promising findings (E201G and I1068V) in an independent sample of >1400 patients and >1100 controls revealed no overrepresentation in patients compared to controls (E201G: 0/1 and I1068V: 0/0). Since I1068V was observed in a single patient, it is impossible to exclude the possibility that I1068V makes a minor contribution to schizophrenia susceptibility. Overall, however, the results do not suggest the existence of rare, highly penetrant NRXN1 mutations in patients with schizophrenia.