Polymorphism of the CLDN5 gene and Schizophrenia in an Iranian Population

Background: The gene coding claudin (CLDN5) is located on 22q11. Since the proteins of CLDN5 family are a ma-jor component for barrier-forming tight junctions, it may be important to test whether or not the CLDN5 locus could be associated with schizophrenia.

Method: A total of 150 individuals affected with schizophrenia and 150 healthy persons were recruited. The relation-ship between the three single nucleotide polymorphism (SNPs) and schizophrenia disease was studied using polymer-ase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) technique. The PCR products were completely digested with restriction enzymes of DpnII, PvuII and BstNI, and then separated on agarose gel. The statis-tical investigations and haplotype analysis were also performed.

Results: The transmission disequilibrium test (TDT) exhibited weak association between rs10314 [C/G] and schizo-phrenia (v2 = 3.55, P = 0.022), but the other two SNPs did not show such an association. The global chi-square test showed that the 3-SNP haplotype system was not associated with schizophrenia although the 1-df test for individual haplotypes showed that the rs1548359(C)-rs10314(G)-rs739371(C) haplotype was excessively non-transmitted (v2 = 6.33, P = 0.025). The v2 test for LD between SNPs indicated that these three SNPs were in strong LD.

Conclusions: Collectively, LD analysis showed that the CLDN5 locus was associated with schizophrenia in an Iranian population.