Background: IFITM3 has been suggested to be associated with infection in some ethnic groups. Diabetes and hypercholesterolemia are also important clinical conditions that can predispose individuals to infection. The aim of this study was to investigate the association of rs12252 C polymorphism, BMI, diabetes, and hypercholesterolemia with mild flu in an Iranian population.
Methods: We conducted a case-control study, including 79 mild flu and 125 flu-negative individuals attending primary care centers of three provinces of Iran (i.e, Markazi, Semnan, and Zanjan). Pharyngeal swab specimens were collected from all participants, and were subjected to RNA and DNA extractions for Real-time PCR and PCR tests. All PCR products were then sequenced to find T/C polymorphisms in the rs12252 region. Data on demographic, anthropometric, and clinical variables were collected from participants' medical records available in the primary care centers. The data was analyzed using DNASIS (v. 2.5) and Stata (v.11) software.
Results: All participants were of Fars ethnic background. The allele frequency for rs12252-C was found to be 9.49% among cases and 2.40% among controls. Carriers of the rs12252 C allele (CT + CC genotypes) showed 5.92 folds increase in the risk of mild flu comparing to the T allele homozygotes (P value: 0.007). We also found a significant positive association between rs12252 C allele heterozygote and mild flu (OR: 7.62, P value: 0.008), but not in C allele homozygote group (OR: 2.71, P value: 0.406). Similarly, we did not find a significant association between mild flu and BMI (OR: 1.06, P value: 0.087), diabetes (OR: 0.61, P value: 0.392), and hypercholesterolemia (OR: 0.50, P value: 0.393) in multivariable logistic regression.
Conclusions: This is the first study evaluating the association between rs12252 polymorphisms, diabetes, hypercholesterolemia, and BMI and susceptibility to mild flu in an Iranian population. Our results suggest a significant positive association between mild flu and rs12252 C allele heterozygous and carriage. Future replication of the strong association observed here between rs12252 C allele carriage and mild flu might candidate this polymorphism as a genetic marker for early screening of susceptibility to mild flu. Lack of significant association between C allele homozygous and mild flu, observed in this study, might be the result of small sample size in this group.
Trial registration: IR.PII.REC.1395.3.
Keywords: Body mass index; Diabetes; Human influenza; Hypercholesterolemia; IFITM3 protein; Iran; Polymorphism.