OBJECTIVETo investigate whether genomic copy number variants (CNVs), within metabotropic glutamate receptors 7 (GRM 7) gene are associated with schizophrenia.

METHODSWe examined CNVs in conserved region of GRM7 using real time quantitative PCR among 180 Chinese schizophrenia cases and 33 normal controls. Products of real time quantitative PCR were sequenced bilaterally.

RESULTSReal time quantitative PCR found that a biallelic deletion existed at the 200 bps up-stream of exon 2 in a schizophrenia patient and a monoallelic deletion existed at this site in another 13 schizophrenia patients and a control subject. However, sequencing results showed a substitution of C to G at the 5bp up-stream of 3' end of reverse primer for real time PCR (GRM7-SV-1R). In addition, samples with this variant were exactly those having biallelic or monoallelic deletions, indicating that the results of the real time PCR were caused by the substitution variant at the 3' end of the primer rather than a bona fide genome deletion.

CONCLUSIONSReal-time quantitative PCR combined with sequencing can avoid false positive deletions and therefore is effective in detecting CNVs. According to our results, CNVs in GRM 7 gene is not associated with schizophrenia in the Han Chinese population. However, some potential rare CNVs may still have such relationship, and require further study.