While family studies have shown clustering of NMO cases in some familites, the exact genetic background of this disorder has not been clarified yet. genetic factors have been enriched pathways related with nervous system and immune responses (43). Another genome-wide study using an SNP array has recognized the rs1964995 in the MHC region as MPS1 a risk locus for NMO. Notably, three MS-associated variants have also been found to be associated with NMO. A variant within gene has been associated with disability score as well as presence of transverse myelitis (27). The importance of copy number variations (CNVs) in conferring risk of NMO has been previously assessed using a genome-wide method. The majority of identified CNVs have been located at TCR and TCR regions. These CNVs have been mostly deletions with sizes of 5 to 50 kb. Since they have been only in the peripheral blood T cells, it has been deduced that they are most probably somatically acquired CNVs. Moreover, it has been an association between the presence of CNVs in NMO cases and seronegativity for AQP4-IgG or low antibody titer (44). Becampanel Several SNPs within gene have been genotyped in NMO cases to find possible risk loci for this condition in different ethnic groups. For instance, Matiello et?al. have compared genotype frequencies of 8 SNPs within gene in sporadic and familial NMO cases as well as healthy controls. One of these SNPs has been found to be associated with risk of NMO. Moreover, two missense mutations at Arg19 have been found in three NMO patients. The authors have reported that apart from one infrequent SNP, no other examined SNP or haplotype has been linked to NMO, possibly excluding the importance of variants in conferring risk of NMO (45). Qiu et?al. have also genotyped eight SNPs in in a group of AQP4-IgG-positive NMO cases. They have shown associations between a number of SNPs and clinical manifestations of NMO such as considerable transverse myelitis, optic neuritis, or simultaneous systemic autoimmune disorders (46). Table?3 shows the results of genomic studies in NMO cases. Table?3 Genomic studies in neuromyelitis optica. genewas associated with EDSS and transverse myelitis. (27)Copy number variationsIdentification phase: 135 NMO/NMOSD patients and 288 healthy controlsSNPs (NC 18.8; chromosome pos. 22695167: T A) was associated with disease. Two different allelic missense mutations, Arg19 (R19I and R19T) was specific to NMO. (45)8 SNPs in exon 1,2,3,4,572 NMO patientsChinesePeripheral blood/sequencing- 6 SNP sites in exons 2 and 5 were recognized in NMO patients.sequence and 10 SNPs64 NMO and 58 NMOSD for sequencingexon 1,2,3,4,527 NMO patients and 40 healthy controlsHan ChinesePeripheral blood/sequencingrs72557968 in exon 2 was identified in one NMO-IgG+ patient. The mutated sequence correlated with higher AQP4-Ab expression. (50) promoters18 NMO patients and 39 healthy controlsSouthern Han ChinesePeripheral blood/PCR and sequencing- Polymorphism at ?1003 bp (A-G) position of promoter 0 was associated with AQP4-Ab presence.exons and 5 SNPs16 AQP4-Ab+ NMO patients and 255 healthy Becampanel controlsJapanesePeripheral blood/sequencing and TaqMan assayT allele of rs2075575 in promoter region was significantly more frequent in NMO and led to downregulation of gene. (52)35 non-MHC MS risk loci110 NMO patients and 332 healthy controlsSoutheastern ChinaPeripheral blood/MALDI-TOF MSOnly rs1800693 in the locus tended to be associated with NMO. (53)Thiopurine nucleotides and SNPs in gene, rs10868138 and rs12378361 were correlated with higher and lower erythrocyte concentration of 6-TGNs, respectively.was associated with lower erythrocyte concentration of 6-MMPNs and 6-MMPNs:6-TGNs ratio. (54) gene were significantly associated with NMO.and gene and rs767455, rs4149577, rs1800693, and ht2, ht3 haplotypes in were significantly associated with NMO. (61)6 SNPs in were significantly associated Becampanel with NMO. (64) in more associated with severity rather than susceptibility. (65)5 SNPs in and (1858 C/T)41 NMO patients and 200 healthy controlsDanish CaucasianPeripheral blood/sequencing and PCR-RFLP-PD-1.3 A allele was associated with NMO.polymorphisms and NMO. (67) gene was significantly higher in NMO patients. (68) was significantly associated with NMO especially in AQP4-Ab+ patients. (69)13 SNPs in polymorphisms and NMO. (72) was the most differentiated gene in the T-cell cluster that downregulated in patients. Furthermore, sIL7Ra and mIL7Ra isoforms Becampanel were also lower in NMO especially AQP4+ samples.(75)mRNAs profile1 NMO patient,1 Parkinson patient and 1 ALS patient__Post mortem Brain tissues/microarray, Real-time PCR, northern blot and Western blot200 genes were significantly upregulated in NMO brain tissue which mostly related to immune regulation involved NF-kB and Becampanel Blimp-1.(76)microRNAs profile9 rituximab-responsive NMO patients,16 nontreated AQP4+ NMO patients and 15 healthy controlsIsraelisPeripheral blood/RNA-seq and real-time PCRmiRNA expression signatures were different in patients compared to healthy controls, also between rituximab.