Effect of rs1344706 in the ZNF804A gene on the connectivity between the hippocampal formation and posterior cingulate cortex.

ZNF804A is one of the most promising candidate genes for schizophrenia. Previous fMRI studies have repeatedly shown an association between SNP rs1344706 in this gene and the functional connectivity from the right dorsolateral prefrontal cortex (rDLPFC) to the left hippocampal formation (lHF) during the N-back task. However, the rDLPFC-lHF functional connectivity included several subconnections and it is not known whether rs1344706 plays the same role in these subconnections. This study addressed that question using both fMRI and DTI data of 87 subjects. First, we replicated the association between rs1344706 and the rDLPFC-lHF functional connectivity using our fMRI data from the N-back task. Second, we reconstructed fiber connections between rDLPFC and lHF using our DTI data, which included three subconnections: from lHF to posterior cingulate cortex (PCC), from PCC to anterior cingulated cortex (ACC), and from ACC to rDLPFC. We found that only the lHF-PCC tract showed significantly lower fractional anisotropy (FA) in risk allele homozygotes. Finally, we analyzed the fMRI data (from the N-back task and the resting state). Both consistently showed relatively lower lHF-PCC functional connectivity in risk allele homozygotes. Taken together, the disconnectivity of the lHF-PCC tract seems to be a plausible intermediate phenotype that links rs1344706 and schizophrenia.