Abnormalities in frontotemporal functional connectivity are also found in siblings of patients with schizophrenia Enzalutamide in vitro [16] and [17], but the heritability of functional connectivity determined from functional MRI (fMRI) is less well established, with one study estimating h2 at 0.42 [18]. It is known that ZNF804A is highly expressed in the brain and that the presence of A-allele

at rs1344704 creates a myelin transcription factor binding site [2] and [19]. The most comprehensive data on ZNF804A function come from neuroimaging and neuropsychology, collectively indicating that rs1344706 is associated with brain function. Esslinger et al. [20] reported reduced functional connectivity between the left and right dorsolateral prefrontal cortices and increased frontotemporal functional connectivity in carriers of the risk allele (A) during a working memory task, findings that were (partly)

replicated in two subsequent studies [16] and [21]. Importantly, Esslinger et al. [22] later showed that the reduced interhemispheric prefrontal connectivity was also apparent during GSI-IX price a facial emotion processing task and during rest, whereas the increased frontotemporal connectivity appeared specific to working memory processes both in the original study and in two replication studies [16] and [21].

This task-independent association of ZNF804A genotype on interhemispheric prefrontal functional connectivity prompted the hypothesis that these effects may be mediated aminophylline by effects on white matter integrity, especially in anterior interhemispheric connections. In contrast, the effects of ZNF804A on frontotemporal connectivity are less likely to be directly mediated by white matter structure since they have only been observed in the context of working memory tasks [21] and [22] and interact with task condition  [16]. In line with this hypothesis, Lencz et al. [23] showed that individuals homozygous for the ZNF804A risk allele (A) have reduced total white matter volumes compared to carriers of the nonrisk allele (C). However, total volumetric measures lack spatial specificity and are particularly susceptible to partial volume effects and segmentation difficulties. DT-MRI is more suited to the study of white matter, and FA is the most commonly used measure of white matter integrity in vivo. Surprisingly, using DT-MRI tractography, Voineskos et al. [19] did not detect any effects of ZNF804A on FA in the uncinate fasciculi, arcuate fasciculi, cingulum or corpus callosum of 62 healthy individuals, 39 C-carriers versus 23 A-homozygotes, aged between 18 and 59 years.