N-acetyltransferase-2 polymorphisms and schizophrenia

Integration of SNPs-FMRI-methylation data with sparse multi-CCA for schizophrenia study

Schizophrenia (SZ) is a complex mental disorder associated with genetic variations, brain development and activities, and environmental factors. There is an increasing interest in combining genetic, epigenetic and neuroimaging datasets to explore different level of biomarkers for the correlation and interaction between these diverse factors. Sparse Multi-Canonical Correlation Analysis (sMCCA) is a powerful tool that can analyze the correlation of three or more datasets. In this paper, we propose the sMCCA model for imaging genomics study. We show the advantage of sMCCA over sparse CCA (sCCA) through the simulation testing, and further apply it to the analysis of real data (SNPs, fMRI and methylation) from schizophrenia study. Some new genes and brain regions related to SZ disease are discovered by sMCCA and the relationships among these biomarkers are further discussed.

A molecular pathway analysis stresses the role of inflammation and oxidative stress towards cognition in schizophrenia

Cognitive processes have a genetic component and are impaired in Schizophrenia (SKZ). The exact nature of such impairment escapes definition. The aim of the present contribution was the identification of the molecular pathways enriched with mutations (SNPs) associated with cognitive performance during antipsychotic treatment. 765 individuals from the CATIE study, males = 559, mean age 40.93 ± 11.03 were included. Working memory and the verbal memory were the evaluated outcomes. A mixed regression model for repeated measures served in R for clinical and molecular pathway analysis. The analysis of quality was conducted under the following criteria: minor allele frequency >0.01, genotype call rate >95%, missing data frequency <5%, Hardy-Weimberg equilibrium threshold >0.0001. The inflation factor was controlled by lambda values. Input for the pathway analysis was SNPs at a p level <0.05 of association genome-wide. Gender, age, education and the duration of the disease were the clinical and socio-demographic variables associated with the cognitive performance. 4268977 SNPs were available after imputation and quality analysis. Pathways related to inflammation and oxidation were the most strongly associated with verbal memory and working memory at a conservative adjusted p value < 0.01. We report that inflammation and in particular the pathway associated with arachidonic acid was enriched in mutations associated with poorer performance at the verbal memory and working memory tasks in SKZ patients.

Association between NAT2 polymorphisms and the risk of schizophrenia in a Northern Chinese Han population

The gene that encodes N-acetyltransferase 2 (NAT2), an enzyme that plays a crucial role in the metabolism of many drugs and xenobiotics, is located on chromosome 8p22, one of the most convictive susceptibility loci of schizophrenia. NAT2 genetic polymorphisms lead to various enzyme acetylation phenotypes. In the present study, six selected NAT2 exonic single nucleotide polymorphisms were genotyped in an independent case-control sample of a Northern Chinese Han population to verify the possible association between NAT2 and schizophrenia. Three (rs1801280T/341C, rs1799930/G590A, and rs1208/A803G) of the six single nucleotide polymorphisms showed significant allele frequency differences between the case and the control groups after rigorous Bonferroni correction. One protective fast-acetylation haplotype (NAT2*4) and two risk slow acetylation haplotypes (NAT2*5B and NAT2*6A) were discovered to be associated with schizophrenia. Our results indicate that NAT2 may be a susceptibility gene for schizophrenia in this Chinese Han population, and the risk haplotypes might cause the impairment of NAT2 in metabolizing neurotoxic substances.

NAT2 sequence polymorphisms and acetylation profiles in Indians

BACKGROUND

NAT2, a broad-spectrum drug-metabolizing gene, is of high pharmacogenetic interest. Based on seven different mutations in the NAT2 gene, an individual can either be categorized as a slow or fast acetylator.

MATERIALS & METHODS

In order to characterize acetylation profiles of Indians, where data are poorly available, we sequenced the 873 bp NAT2 coding region in 250 Indians, covering the whole of India including three tribes.

RESULTS

Altogether, 35 NAT2 alleles forming two acetylator phenotypes (distributed almost in equal proportion in India) were found; while the alleles determining slow acetylators were highly differentiated, the fast acetylator alleles were less in number but highly frequent.

CONCLUSION

Interestingly, distribution of two different acetylation phenotypes correlated well with historical dietary pattern in India. The neighbor-joining phylogenetic tree based on NAT2 gene polymorphisms in worldwide humans revealed genetic affinities among populations with similar acetylation phenotypes, which also placed Indians and Africans together in a single cluster.

Chromosome 8p as a potential hub for developmental neuropsychiatric disorders: implications for schizophrenia, autism and cancer

Defects in genetic and developmental processes are thought to contribute susceptibility to autism and schizophrenia. Presumably, owing to etiological complexity identifying susceptibility genes and abnormalities in the development has been difficult. However, the importance of genes within chromosomal 8p region for neuropsychiatric disorders and cancer is well established. There are 484 annotated genes located on 8p; many are most likely oncogenes and tumor-suppressor genes. Molecular genetics and developmental studies have identified 21 genes in this region (ADRA1A, ARHGEF10, CHRNA2, CHRNA6, CHRNB3, DKK4, DPYSL2, EGR3, FGF17, FGF20, FGFR1, FZD3, LDL, NAT2, NEF3, NRG1, PCM1, PLAT, PPP3CC, SFRP1 and VMAT1/SLC18A1) that are most likely to contribute to neuropsychiatric disorders (schizophrenia, autism, bipolar disorder and depression), neurodegenerative disorders (Parkinson's and Alzheimer's disease) and cancer. Furthermore, at least seven nonprotein-coding RNAs (microRNAs) are located at 8p. Structural variants on 8p, such as copy number variants, microdeletions or microduplications, might also contribute to autism, schizophrenia and other human diseases including cancer. In this review, we consider the current state of evidence from cytogenetic, linkage, association, gene expression and endophenotyping studies for the role of these 8p genes in neuropsychiatric disease. We also describe how a mutation in an 8p gene (Fgf17) results in a mouse with deficits in specific components of social behavior and a reduction in its dorsomedial prefrontal cortex. We finish by discussing the biological connections of 8p with respect to neuropsychiatric disorders and cancer, despite the shortcomings of this evidence.