Cognitive outcome and gamma noise power unrelated to neuregulin 1 and 3 variation in schizophrenia

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[Background]: Neuregulins are a family of signalling proteins that orchestrate a broad range of cellular responses. Four genes encoding Neuregulins 1-4 have been identified so far in vertebrates. Among them, Neuregulin 1 and Neuregulin 3 have been reported to contribute to an increased risk for developing schizophrenia. We hypothesized that three specific variants of these genes (rs6994992 and rs3924999 for Neuregulin 1 and rs10748842 for Neuregulin 3) that have been related to this illness may modify information processing capacity in the cortex, which would be reflected in electrophysiological parameters (P3b amplitude or gamma noise power) and/or cognitive performance. [Methods]: We obtained DNA from 31 patients with schizophrenia and 23 healthy controls and analyzed NRG1 rs6994992, NRG1 rs3924999 and NRG3 rs10748842 promoter polymorphisms by allelic discrimination with real-time polymerase chain reaction (PCR). We compared cognitive outcome, P300 amplitude parameters and an electroencephalographic measure of noise power in the gamma band between the groups dichotomized according to genotype. [Results]: Contrary to our hypothesis, we could not detect any significant influence of variation in Neuregulin 1/Neuregulin 3 polymorphisms on cognitive performance or electrophysiological parameters of patients with schizophrenia. [Conclusions]: Despite our findings, we cannot discard that other genetic variants and, more likely, interactions between those variants and with genetic variation related to different pathways may still influence cerebral processing in schizophrenia.
Funding for this study was provided by the Instituto de Salud Carlos III Grants 080017 and 1102203 to VM, Gerencia Regional de Salud de Castilla y León GRS 249/A/08 and 613/A/11, a postdoctoral Marie Curie Intra European Fellowship within the 7th European Commission Framework Programme for Research and Innovation (330156-CODIP) to ÁD, a predoctoral research grant from the Consejería de Educación - Junta de Castilla y León and the European Social Fund to ÁD (EDU/1486/2008) and CC (EDU/1064/2009), a predoctoral scholarship from the University of Salamanca and Santander Bank to VS, and the FIS Grant PI 1000219 to RG.