Protocadherins (PCHD) are cell adhesion proteins with an important role in neuronal migration, differentiation and synaptogenesis. The linkage studies suggest that the 5q31-linked protocadherin family locus should be considered as potential candidate locus in schizophrenia and bipolar disorder. In this study, we focused particularly on single-nucleotide polymorphisms (SNPs) located in PCHDα enhancer. Results from the Czech cohort of patients with bipolar disorder (BD) will be presented.

Unrelated inpatients and outpatients with BD based on Schedule for Affective Disorders and Schizophrenia - Lifetime (n=167) and blood bank donors as control subjects (n=211) were recruited in the study. Four SNPs posted in dbSNP (rs31745, rs10036519, rs3756337 and rs59497) in the PCDHα gene enhancer were analyzed. The data sets were analysed using a case control design.

In case of SNP, rs31745, a significant increase in homozygosity for the minor allele (T) was detected in patients with BD; 5% had this genotype, but no controls (p=0.001). The distribution of allels did not differ between patients and controls. No significant differences were found in allele or genotype distribution for three other SNPs.

The findings suggest that the PCHDα is an interesting gene family to consider in BD susceptibility.