Multiple sclerosis (MS) is an autoimmune disorder of central nervous system with several genetic and environmental risk factors. Genes with regulatory roles on immune system have been implicated in its pathogenesis. Recently, long non-coding RNAs (lncRNAs) have been demonstrated to control some aspects of immune response. Among them is antisense non-coding RNA in the INK4 locus (ANRIL) whose involvement in NF-κB signaling pathway has been highlighted. In the current study, we evaluated the association between rs1333045, rs4977574, rs1333048, and rs10757278 variants of ANRIL and MS risk in a population of 410 Iranian MS patients and 410 healthy subjects. There was no significant difference in allele and genotype frequencies between MS patients and healthy subjects. However, haplotype analysis (rs1333045, rs1333048, rs4977574, and rs10757278 respectively) demonstrated protective effect of CCGG and TAAA haplotypes against MS (P values of 0.043 and 0.0026 respectively). In addition, TAGG and CCGA haplotypes were significantly associated with MS risk in the studied population (P values of 0.0065 and 0.024 respectively). The present study reveals a possible role for ANRIL in the pathogenesis of MS.

Ras-like without CAAX2 (RIT2) which encodes a GTP-binding protein has recently been reported as a new susceptibility gene for Autism Spectrum Disorders (ASD) in a genome-wide association study. Since the gene is suggested to be involved in the pathogenesis of different neurological diseases, we investigated the association of two single nucleotide polymorphisms (SNP) rs16976358 and rs4130047 of this gene with ASD in Iranian patients. A total of 1004 individuals, comprising 532 ASD cases and 472 healthy subjects participated in this study. Allele frequency analyses showed significant over-presentation of rs16976358-C allele in cases versus controls (P < 0.0001). In addition, rs16976358 CC genotype (OR (95% CI) =3.57(1.72-7.69) and P < 0.0001) and rs4130047 CC genotype (OR (95% CI) =0.64(0.43-0.97) and P = 0.035) were associated with ASD in recessive inheritance model. Besides, haplotype analysis demonstrated an association between the C/T haplotype block (rs16976358/rs4130047) and ASD (OR (95%CI) = 0.44 (0.31-0.62), P < 0.0001). Altogether, our findings provided additional confirmation for the RIT2 gene participation in ASD risk and suggested the rs16976358 variant as a possible genetic risk factor for this disorder.

Short tandem repeats (STRs) are commonly defined as short runs of repetitive nucleotides, consisting of tandemly repeating 2-6-bp motif units, which are ubiquitously distributed throughout genomes. Functional STRs are polymorphic in the population, and their variations influence gene expression, which subsequently may result in pathogenic phenotypes. To understand STR phenotypic effects and their functional roles, we describe four different mutational mechanisms including the unequal crossing-over model, gene conversion, retrotransposition mechanism and replication slippage. Due to the multi-allelic nature, small length, abundance, high variability, codominant inheritance, nearly neutral evolution, extensive genome coverage and simple assaying of STRs, these markers are widely used in various types of biological research, including population genetics studies, genome mapping, molecular epidemiology, paternity analysis and gene flow studies. In this review, we focus on the current knowledge regarding STR genomic distribution, function, mutation and applications.