Association Between FCN2 Exon 8 Polymorphisms And Children With Recurrent Respiratory Tract Infection

Background: L-ficolin was a plasma protein of hepatic origin and derived from FCN2. It was able to bind such elongated carbohydrates with acetylated and neutral residues like 1,3-b-D-glucan, present on microbial and apoptotic surfaces. FCN2 promoter polymorphisms were associated with marked changes in the L-ficolin serum concentration, whereas two polymorphisms clustered in the exon 8 encoding the fibrinogen-like domain were associated with increased and decreased GlcNAc binding, respectively.Objective: To elucidate the association between polymorphisms of the Thr236Met and Ala258Ser in the FCN2 and the incidence of RRTI in Han Chinese children of Changzhou, Jiangsu.Method: To carry on a case-control study, we selected the children who were in hospital from Feb 2008 to Feb 2009 and divided them into RRTI group and control group according to the parental questionnaires. Diagnostic criteria was accorded with Chinese Academy of Pediatrics in 1987 on recurrent respiratory tract infections. The genotypes of Thr236Met and Ala258Ser polymorphisms in the L-ficolin gene were detected by polymerase chain reaction (PCR) and base-quenched probe technique in 104 RRTI children and 214 controls. Patients in tow groups were matched for sex and age.Results: The polymorphisms in exon 8 (Thr236Met and Ala258Ser) were detected in 104 RRTI children and 214 controls. There are two genotypes of Thr236Met, one is CC wild-type homozygote and the other is TC heterozygote; They possess 91.3% and 8.7% in RRTI group respectively , 90.2% and 9.8% in control respectively. The TT mutant homozygote was found neither in case nor in control group. There were not significant differences between case and control(P>0.05). The allele frequencies of T were 4.3% and 4.9% in the two groups respectively. According to the assay, there were not significant differences between the two(P>0.05). Nearly the same frequencies at Ala258Ser locus were found in two groups as follows:GG(63.5%), TG (31.7%) and TT(4%) in case group, as well as GG(66.4%), TG (31.5%) and TT(2%) in control. The allele frequencies of T were 20.7% and 18.1% in the two groups respectively.There were still no significant differences between two groups (P>0.05).Conclusion: The polymorphisms in FCN2 exon 8 (Thr236Met and Ala258Ser) do not seem to contribute to predict RRTI in Chinese children of Changzhou.