Biological Validation of Increased Schizophrenia Risk With NRG1, ERBB4, and AKT1 Epistasis via Functional Neuroimaging in Healthy Controls

Abstract

CONTEXT NRG1 is a schizophrenia candidate gene and plays an important role in brain development and neural function. Schizophrenia is a complex disorder, with etiology likely due to epistasis. OBJECTIVE We sought to examine epistasis between NRG1 and selected NMDA-glutamate pathway partners implicated in its effects, including ERBB4, AKT1, DLG4, NOS1, NOS1AP. DESIGN Schizophrenia case-control sample analyzed using machine learning algorithms and logistic regression with follow-up using neuroimaging on an independent sample of healthy controls. PARTICIPANTS A referred sample of schizophrenic patients (N = 296) meeting DSM-IV criteria for schizophrenia-spectrum disorder and a volunteer sample of controls for case-control comparison (N = 365) and a separate volunteer sample of controls for neuroimaging (N = 172). MAIN OUTCOME MEASURES Epistatic association between SNPs and case-control status; epistatic association between SNPs and the BOLD physiological response during working memory measured by functional magnetic resonance imaging (fMRI). RESULTS We observed interaction between NRG1 5’ and 3’ SNPs: rs4560751-rs3802160 (likelihood ratio test (LRT) p=0.00020) and schizophrenia which was validated using fMRI of working memory in healthy controls; carriers of risk-associated genotypes showed inefficient processing in dorsolateral prefrontal cortex (DLPFC) (p=0.015, FWE corrected). We observed epistasis between NRG1 (rs10503929; Val1066Ile) and its receptor ERBB4 (rs1026882; LRT p=0.035); a three-way interaction with these two SNPs and AKT1 (rs2494734) was also observed (OR=27.13; 95% confidence interval 3.30, 223.03; LRT p=0.042). These same two- and three-way interactions were further biologically validated via fMRI: healthy individuals carrying risk genotypes for NRG1 and ERBB4, or these two together with AKT1, were disproportionately less efficient in DLPFC processing. Lower-level interactions were not observed between NRG1/ERBB4-AKT1 in association or neuroimaging, consistent with biological evidence that NRG1-ERBB4 interaction modulates downstream AKT1 signaling. CONCLUSIONS Our data suggest complex epistatic effects implicating a NRG1 molecular pathway in cognitive brain function and the pathogenesis of schizophrenia.

The genetic contribution of the NO system at the glutamatergic post-synapse to schizophrenia: Further evidence and meta-analysis

“…Titles and abstracts were scrutinized to exclude non-genetic studies, reducing the number of included studies to Costain et al, 2010;Fang et al, 2008;Greenwood et al, 2011;Husted et al, 2010;Kremeyer et al, 2009;Miranda et al, 2006;Nicodemus et al, 2008;Wratten et al, 2009) and one on NOS1 (Fallin et al, 2005), presented family-based, but not case-control data and were therefore not integrated in the meta-analysis for methodological reasons. The remaining studies on NOS1AP (n=6; (Aberg et al, 2010;Delorme et al, 2010;Nicodemus et al, 2010;Puri et al, 2007;Puri et al, 2006;Zheng et al, 2005)) and NOS1 (n=14; (Cui et al, 2010;Donohoe et al, 2009;Kawohl et al, 2008;Nicodemus et al, 2010;O'Donoghue et al, 2012;Okumura et al, 2009;Reif et al, 2006;Reif et al, 2011;Riley et al, 2010;Rose et al, 2012;Shinkai et al, 2002;Silberberg et al, 2010;Tang et al, 2008;Wang et al, 2012)) reported on case-control association data and were scrutinized in greater detailed. For NOS1AP, two and for NOS1, 11 further studies had to be excluded from meta-analysis for the following reasons.…”

“…For the NOS1 gene: (Kawohl et al, 2008;O'Donoghue et al, 2012;Rose et al, 2012) analysed exclusively healthy participants. (Donohoe et al, 2009;Nicodemus et al, 2010;Riley et al, 2010) and (Shinkai et al, 2002) only presented data on SNPs which have not been genotyped for the present study; no SNP data could be obtained from the study of (Wang et al, 2012); and the study by (Silberberg et al, 2010) was excluded because of the rather small sample size (n=26) precluding meaningful interpretation of the data. Finally, (Reif et al, 2011) and (Reif et al, 2006), were excluded because the case samples of both studies overlapped with the sample described here (while the control sample was extended more than two-fold).…”

“…Subsequently, our group conducted a mutation analysis, qRT PCR and haplotype analysis in Caucasian patients suffering from schizophrenia arguing that a functional promoter SNP (rs41279104), resulting in decreased expression of a reporter gene in cell culture experiments (Saur et al, 2004), is associated with disease (Reif et al, 2006a). Since then, six more case-control association studies on schizophrenia and NOS1 were published in total (Cui et al, 2010;Nicodemus et al, 2010;Okumura et al, 2009;Riley et al, 2010;Tang et al, 2008;Wang et al, 2012). Four of those came from Asian populations (two Chinese and two Japanese (Cui et al, 2010;Okumura et al, 2009)), with mixed results: while Cui and associates replicated the positive finding on rs41279104 (and also provided evidence for reduced NOS-I expression on the protein level in BA9 -part of the dorsolateral prefrontal cortex -for risk allele carriers), Okumura could not, although two other NOS1 SNPs were significant (but did not survive correction for multiple testing).…”

“…In contrast, the other study from China found significant evidence for an association of NOS1 (5'UTR and intron 2) with schizophrenia as well. One Irish population did not provide evidence for an association of NOS1 with schizophrenia, although only 4 SNPs were tested and did not include the previously significant rs41279104 (Nicodemus et al, 2010). Taken together, these association studies rather argue for an association of the 5' end of NOS1 -especially the promoter region -with schizophrenia.…”

“…Following up the studies of Brzustowicz and colleagues, both positive (Kremeyer et al, 2009;Miranda et al, 2006;Zheng et al, 2005) as well as negative Nicodemus et al, 2010;Nicodemus et al, 2008) family-based and case-control studies were published. In addition, a mutation analysis suggested that rare coding variants in NOS1AP underlie obsessive-compulsive disorder and autism (Delorme et al, 2010).…”