Screening of IL-22 first and second introns and FOXP3 second exon for SNPs and mutations with potential role in the susceptibility of SLE in selected population

OBJECTIVE

The main objective of performing this study was the mutational analysis of Forkhead box family member (FoxP3) and Interleukin-22 (IL-22) genes and their associations with systemic lupus erythematosus (SLE).

MATERIALS AND METHODS

A total of sixty blood samples were collected from SLE patients from different hospitals in Lahore. Proforma was based on American College of Rheumatology (ACR) criteria. The total time for this research was one year (2018-2019). DNA was extracted, and FoxP3 and IL-22 genes were polymerized through PCR and further sequenced through the Sanger Sequencing method. Chromas version 2.6.6 was used for the similarity index of sequences. NG_060763 and NG_007392.1 were used as Reference Sequences of IL-22 and FoxP3 genes, respectively.

RESULTS

Three already identified Single Nucleotide Polymorphisms (SNPs) in the IL-22 gene i.e., rs2227491, rs2227485, and rs2227513, were confirmed in the sequencing results of SLE patients. Results showed that there were nine novel mutations (27.27%) in the case of the IL-22 gene in the studied genotyped samples. These SNPs had remarkably increased allele T frequency in rs2227485 and allele C frequency in rs2227491 and rs2227513. On the other hand, in the case of FoxP3 gene exon 2, there was an addition of T at position 10 in the intronic portion, thus not involved in the progression of the disease.

CONCLUSIONS

The importance of cytokine-mediated signaling pathways, such as the IL-22 gene, is thus established. Novel variants in the IL-22 gene likely contributed significantly to the development of this autoimmune disorder. The current study found that the dysregulation of the inflammatory markers in SLE is not related to the FoxP3 gene, even though FoxP3 is implicated in the tolerance process.