ORIGINAL RESEARCH ARTICLE Precursor miR-499a Variant but not miR-196a2 is Associated with Rheumatoid Arthritis Susceptibility in an Egyptian Population Eman A. Toraih 1 • Nesreen M. Ismail 2 • Ahmed A. Toraih 3 • Mohammad H. Hussein 4 • Manal S. Fawzy 5 Ó Springer International Publishing Switzerland 2016 Abstract Introduction Rheumatoid arthritis (RA) has a complex component induced by several genes that interact together with environmental and hormonal factors. We aimed to investigate the association of miR-196a2 rs11614913 (C/T) and miR-499a rs3746444 (A/G) polymorphisms and their combination with RA susceptibility and disease activity in an Egyptian population, and to evaluate their impact on methotrexate drug response and toxicity. Materials and Methods Bioinformatics databases were searched to select potential micro RNA (miRNA)–mes- senger RNA (mRNA) interactions involved in RA patho- genesis. Ninety-five RA patients diagnosed according to the American College of Rheumatology and 200 healthy controls were genotyped using real-time polymerase chain reaction technology. Results In overall and stratified analysis, miR-499a, but not miR-196a2, was associated with RA risk. Heterozygote carriers with rs3746444*A/G displayed protection against developing RA (p = 0.005) with an odds ratio of 0.2 (95 % confidence interval 0.17–0.62). The carriage of the com- binations (miR499a*AG ? miR196a2*CC) and (miR499- a*AA ? miR196a2*TT) were 3 and 7.5 times more likely to develop RA, respectively, while the combinations (miR499a*GG ? miR196a2*CC), (miR499a*AG ? miR196a2*TT) and (miR499a*AA ? miR196a2*CT) show less susceptibility to have RA disease (all p \ 0.05). rs3746444*AA genotype had a higher disease activity score (DAS28) [p = 0.023], tender joint count (TJC) (p = 0.007), and methotrexate-induced gastrointestinal toxicity (p = 0.043) compared with both AG/GG geno- types. rs11614913*C carriers were associated with higher DAS28 activity (p = 0.021). Homozygote male patients (CC and TT) had higher TJC (p = 0.046) and higher rheumatoid factor levels (p = 0.026), whereas, TT homozygote females had higher levels of ALT (p = 0.022). Conclusions Different genotypes of miR-499a rs3746444 single nucleotide polymorphisms (SNPs) are associated with RA risk, disease activity, and methotrexate toxicity in our population. In combination with specific miR-196a2 rs11614913 genotypes, this risk could increase or decrease according to the type of combination. Further functional analysis of the SNP and its impact on mRNA targets is required to confirm the relationship between genotype and phenotype. Electronic supplementary material The online version of this article (doi:10.1007/s40291-016-0194-3) contains supplementary material, which is available to authorized users. & Eman A. Toraih emantoraih@gmail.com & Manal S. Fawzy manal2_khashana@ymail.com 1 Department of Histology and Cell Biology (Genetics Unit), Faculty of Medicine, Suez Canal University, Ismailia, Egypt 2 Department of Rheumatology and Rehabilitation, Faculty of Medicine, Suez Canal University, Ismailia, Egypt 3 Department of Orthopedic Surgery, Faculty of Medicine, Suez Canal University, Ismailia, Egypt 4 Department of Chest Disease, Faculty of Medicine, Cairo University, Giza, Egypt 5 Department of Medical Biochemistry, Faculty of Medicine, Suez Canal University, PO 41522, Ismailia, Egypt Mol Diagn Ther DOI 10.1007/s40291-016-0194-3