Statistical analyses:
All statistical analyses were performed by IBM SPSS statistics 21.0 (IBM Corp. Armonk, NY, USA), R Statistical software (version 4.0.3; R Foundation for Statistical Computing, Vienna, Austria), and GraphPad PRISM5 software (GraphPad Software Inc, San Diego, CA, USA). Fisher’s exact test and Pearson’s chi-square test were used for individual parameter analysis. For testing the association between polymorphism and outcomes, we used Firth logistic regression that uses a penalized likelihood to remove much of the bias from the maximum likelihood estimates in the logistic regression model 28. This method is best suited for the present study as the genetic variants tested are rare. Log Rank Mantel-Cox regression analysis was used for the survival analysis.