Association study between the Down syndrome cell adhesion molecule (DSCAM) gene and bipolar disorder

Defects of neurodevelopmental processes are suggested to underlie the pathogenesis of bipolar disorder. Down syndrome cell adhesion molecule (DSCAM), a member of neural immunoglobulin superfamily playing a diverse role for neural development, is mapped to chromosome 21q22, a linkage locus for bipolar disorder, and is, therefore, an interesting candidate for the disease.

We performed a variation screening of the gene and association studies in 22 multiplex bipolar pedigrees of Caucasian descent and 119 Japanese patients with bipolar disorder and 140 controls. Expression levels of DSCAM were also examined in postmortem brains from the Stanley Medical Research Institute.

We found 27 single nucleotide polymorphisms in DSCAM. Possible associations of SNP DC141 (IVS27-15A>G; P=0.042) and DC142 (IVS29+328C>A; P=0.036) were observed in pedigree samples, and G allele of DC141 was correlated with increased expression levels of DSCAM (P=0.038) in postmortem brains. Possible association of DC136 (4749C>T), which is in the same haplotype block with DC141 and DC142, was detected in Japanese populations (P=0.049).

These results suggest the possible contribution of DSCAM gene in bipolar disorder, and warrant further investigations.