5, and less likely to have the variant genotype; the converse was the found in patients with schizophrenia. First-degree relatives were not included in this analysis. Raux71 and colleagues studied two related α7

genes (CHRNA7 and CHRNA7-like gene) resulting from a partial duplication (from exon 5 to exon 10) in the human genome. They described two types of genetic variation (i) a large deletion resulting in a truncation of the open reading frame; and (ii) a -2 bp deletion in exon 6, which specifically affected the CHRNA7-like gene. MK0683 manufacturer Genotyping 70 schizophrenic Inhibitors,research,lifescience,medical patients and 77 controls who had had P50 ERP recorded, Raux and colleagues found that carrying at least one -2 bp deletion of exon 6 did not constitute a risk factor for schizophrenia; on the contrary, healthy Inhibitors,research,lifescience,medical control subjects were more likely to have

the -2 bp deletion of exon 6 associated with P50 ratio >0.45. The authors of this study concluded that Inhibitors,research,lifescience,medical the -2 bp deletion within the CHRNA7-like gene is a risk factor for P50 sensory gating deficit, but not for schizophrenia. In a subsequent study,72 the same group was unable to replicate the CHNRA7 core promoter variant findings described by Leonard et al,70 but found a -194C CHNRA7 promoter polymorphism that was also associated with a P50 ratio <0.50 as in the Leonard et al study, except that this allele was also more frequent in the control group. The authors suggested that this was a case where the variant allele rendered a protective effect against the P50 ratio deficit, and the -194C polymorphism was

in linkage disequilibrium with causal variants of Inhibitors,research,lifescience,medical the deficit. Although the evidence to support a functional association of CHRNA Inhibitors,research,lifescience,medical 7 promoter variants with susceptibility to schizophrenia is weak, it may still be the case that CHRNA 7 modulates inhibitory factors in the P50 ERP and, in similar fashion perhaps, modulation of clinical symptoms in schizophrenia. P300 oddball ERPs The P300 oddball ERP is a cognitive electrophysiological paradigm elicited within a 250- to 450-ms poststimulus window when a subject detects a low probability target stimulus. The maximum amplitude of the P300 response is recorded from temporoparietal scalp leads. else A number of laboratories5,73-79 including ours,5,77 have found the P300 left temporoparietal component amplitude distinguishes patients with schizophrenia from healthy controls. However, whether P300 oddball amplitude is a plausible intermediate phenotype in schizophrenia remains undetermined. The crux is the question of heritability; the issue is whether siblings share a putative phenotype; and for this the evidence is decidedly mixed.