IL4 and periodontitis: Therefore, genetic polymorphisms in the IL4 gene may aggravate periodontal disease severity by altering IL-4 levels and studies suggested that the -33 C/T∗T allele was correlated with increased IL-4 expression [21, 22]. IL4 and IL13 are functionally relevant and only through the combined analyses of genetic polymorphisms in IL4 and IL13 genes could their actual roles in the development of periodontitis be revealed [23].