Associations of IRAK1 Gene Polymorphisms and mRNA Expression With NMOSD Risk in the Northern Chinese Han Population

Association of Epistatic Effects of lncRNA GAS5, miR-146a, IRAK-1, and miR-155 Genetic Variants with Multiple Sclerosis Risk and Severity

The complex genetic architecture of heritability in multiple sclerosis (MS) remains undisclosed mainly. Epistasis (gene-gene interaction) substantially impacts MS; however, it is largely unexplored, especially among the non-coding RNA genes and their targets. The long non-coding RNA GAS5 exacerbates demyelination and sponges miR-146a and miR-155, impeccable contributors to MS pathogenesis. miR-146a negatively regulates the immune responses by targeting IRAK-1. We investigated the association of epistatic effects and haplotypes of five single nucleotide polymorphisms (SNPs), GAS5 rs2067079, miR-146a rs2910164 and rs57095329, IRAK-1 rs3027898, and miR-155 rs767649, with the risk of MS and its phenotypes. The expression quantitative trait locus (eQTL) associated with these variants was explored through bioinformatics analysis. The study enrolled 116 MS patients and 120 healthy controls. No strong linkage disequilibrium (D' ≥ 0.8) was detected among the studied SNPs. SNP-SNP interactions overlaid an overall magnified risk of MS and its phenotypes compared to the single-locus effects. After adjustment for multiple comparisons, the most significant interactions associated with the risk of overall MS and secondary-progressive MS were rs2067079-rs2910164, rs2910164-rs57095329, and rs3027898-rs767649. The last two former SNP-SNP interactions were highly associated with relapsing-remitting MS risk. The same pattern of interactions, as observed in association with MS risk, was female-specific. The CCAAA haplotype (alleles in the order of rs2067079, rs2910164, rs57095329, rs3027898, and rs767649) was protective against MS risk (CCAAA vs. CGAAT, adjusted OR = 0.14, 95% CI = 0.03-0.69, P = 0.009). Among MS patients, harboring the CGACT and CGAAT haplotypes was more prevalent in females and males, respectively. MS patients having EDSS ≥ 6 had a significantly higher frequency of the CCGCA haplotype than those with EDSS < 6. Functional analysis revealed rs2067079, rs57095329, and rs767649 as strong cis-eQTL regulating multiple genes, particularly in the brain and immune system. We propose that a magnified combined effect of GAS5, miR-146a, IRAK-1, and miR-155 genetic variants via epistatic interactions might impact the risk of MS and its phenotypes and could help in the risk stratification of MS patients.

Association between FOXP3 polymorphisms and expression and neuromyelitis optica spectrum disorder risk in the Northern Chinese Han population

Background

Forkhead box P3 (FOXP3) plays a critical role in the pathogenesis of autoimmune disorders. In the present study, we genotyped three single-nucleotide polymorphisms, namely, rs2232365, rs3761548, and rs3761549, to determine the relationship between FOXP3 polymorphisms and neuromyelitis optica spectrum disorder (NMOSD) susceptibility among the Northern Chinese Han population.

Materials and methods

We genotyped single nucleotide polymorphisms at loci of the FOXP3 gene (rs2232365, rs3761548, and rs3761549136) in 136 NMOSD patients and 224 healthy subjects using the multiplex SNaPshot technique. Allele, genotype, and haplotype frequencies were compared. qPCR was used to analyze the mRNA expression levels of FOXP3 in the peripheral blood mononuclear cells of 63 NMOSD patients and 35 healthy subjects. Non-parametric tests were used to test the FOXP3 mRNA expression across the different groups.

Results

The minor allele frequency (MAF) of G in rs2232365 was markedly lower in the NMOSD group than in the control group (odds ratio [OR] = 0.57, 95% confidence interval [95% CI]: 0.41-0.79, p = 0.001). Using genetic (codominant, dominant, and recessive) models and performing haplotype analyses, the MAF of G in rs2232365 was shown to be associated with protection against NMOSD in this population. Furthermore, haplotype analysis revealed that the haplotype GCT and the rs2232365, rs3761548, and rs3761549 alleles predicted protection against NMOSD (OR = 0.63, 95% CI = 0.41-0.97, p = 0.038). The proportions of the three genotypes of rs2232365 (p = 0.001) were not significantly different between the moderate-to-severe (Expanded Disability Status Scale (EDSS) ≥ 3 points) and mild (EDSS < 3 points) groups. Evidently, the proportion of patients with the AA genotype (64.3%) among the rs2232365 patients was significantly greater in the moderate-to-severe group than in the mild group (36.4%). However, the proportion of patients with the GG genotype (15.2%) among the rs2232365 patients was significantly greater in the mild group than in the moderate-to-severe group (2.9%). The mRNA expression of FOXP3 was markedly greater in the NMOSD group than in the control group (p = 0.001). Nevertheless, acute non-treatment patients exhibited lower FOXP3 mRNA expression than healthy controls and patients in the remission group (p = 0.004 and 0.007, respectively).

Conclusion

FOXP3 polymorphisms and haplotypes are related to NMOSD susceptibility among the Han Chinese population. The minor allele G of FOXP3 rs2232365 and the haplotype GCT are associated with protection against NMOSD. The GG genotype may decrease the severity of NMOSD, whereas the AA genotype is related to moderate-to-severe NMOSD. FOXP3 mRNA expression is greater in patients with NMOSD than in healthy controls. However, it is decreased in acute non-treatment patients compared with healthy controls.

Sex differences in susceptibility to substance use disorder: Role for X chromosome inactivation and escape?

There is a sex-based disparity associated with substance use disorders (SUDs) as demonstrated by clinical and preclinical studies. Females are known to escalate from initial drug use to compulsive drug-taking behavior (telescoping) more rapidly, and experience greater negative withdrawal effects than males. Although these biological differences have largely been attributed to sex hormones, there is evidence for non-hormonal factors, such as the influence of the sex chromosome, which underlie sex disparities in addiction behavior. However, genetic and epigenetic mechanisms underlying sex chromosome influences on substance abuse behavior are not completely understood. In this review, we discuss the role that escape from X-chromosome inactivation (XCI) in females plays in sex-associated differences in addiction behavior. Females have two X chromosomes (XX), and during XCI, one X chromosome is randomly chosen to be transcriptionally silenced. However, some X-linked genes escape XCI and display biallelic gene expression. We generated a mouse model using an X-linked gene specific bicistronic dual reporter mouse as a tool to visualize allelic usage and measure XCI escape in a cell specific manner. Our results revealed a previously undiscovered X-linked gene XCI escaper (CXCR3), which is variable and cell type dependent. This illustrates the highly complex and context dependent nature of XCI escape which is largely understudied in the context of SUD. Novel approaches such as single cell RNA sequencing will provide a global molecular landscape and impact of XCI escape in addiction and facilitate our understanding of the contribution of XCI escape to sex disparities in SUD.