MS+Discussion

**__Discussion__**
Inflammatory demyelinating diseases, especially MS, are considered to be a type of autoimmune diseases that arise in individuals with genetic predisposition (Li et al., 2016). The cytokine IL23A has significant effects in the differentiation of pro-inflammatory cells, and these cells have been deemed to be the key factors in the pathogenesis of MS. Also, it has been stated that more than 90% of MS patients have humoral responses, and the serum level of IL23A may represent autoimmune disease types and progression.In a previous study, it was found that the serum levels of IL23A in MS patients were greater than those in the normal groups//.//Since functional genetic variants within the IL23A gene have important impacts on the host immune response, they could be good candidates as a focus for genetic association studies//.// In conclusion, it was found that three variants (rs2066808, rs2371494, and rs11575248) in the IL23A gene were associated with the risk of MS and other IDD, and the serum levels of IL23A in the MS patients were changed by the variants, which offers new evidence for the significance of IL23A in the pathogenesis of MS. (Li et al., 2016).

Minor allele frequency is widely used in population genetics studies because it provides information to differentiate between common and rare variants in the population. Rare variants have a MAF less than 0.5%. Common variants have a MAF of greater than 5%. The rs2371494 SNP has a MAF much greater than 5% for all populations. This means that rs2371494 is a very common variant.

Since the results make it seem like there is a higher risk for MS closer to the equator (South America, Africa, South Asia), maybe there is a greater risk of MS for populations in warmer climates. Likelihood ratio calculates the likelihood of the disease conditioned upon a risk genotype, which is the probability of the genotype among the diseased individuals divided by is the probability of the genotype among the healthy controls (Dudley & Karczewski, 2014). It expresses how many times more likely the data are under one model or the other. It’s log (log likelihood ratio) can be used to compute p-value, or compared to a critical value to decide whether to reject the null hypothesis. The mean likelihood ratio of the Pima population is 0.772. A likelihood ratio of 0.772 indicates a minimal decrease in the likelihood of multiple sclerosis. The Pima population has a low risk of multiple sclerosis.

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