Associations of SNP rs_7927894 of FLG gene and TARC/CCL17 with atopic dermatitis in children

Abstract

One of the main genetic factors of the development of atopic dermatitis (AD) in children are single nucleotide polymorphisms (SNP) of the filagrin gene (FLG), particularly rs_7927894 FLG. One of the mostly studied and promising AD marker chemokines (CK) is the thymusE and activation regulated chemokine (TARC/CCL17).

Purpose – to detect the associations and role of different variants of SNP rs_7927894 FLG gene and TARC/CCL17 in children suffering different AD clinical proE files (CP) – isolated or combined with comorbid atopic disorders (AtD).

Materials and methods. The main group comprised 39 patients aged 3 to 18 years, suffering the isolated AD or combined with comorbid AtD. The control group comprised 47 patients aged 3 to 18 years, suffering the pathology of gastrointestinal tract without clinical signs of atopy. All the patients of the main and control groups had undergone detection of the genotype variants of SNP rs_7927894 FLG gene by real-time polymerase chain reaction and detection of TARC/CCL17 serum concentrations in venous blood. The cutEoff value of statistical significance was set as p<0.05.

Results. The incidence and association of genotype variants C/C, C/T and T/T SNP rs_7927894 FLG gene in patients of cohorts of the studied groups were detected as follows: C/T rs_7927894 FLG was significantly the most common in the general main group (56.4%, p<0.05), within the cohort of CP AD isolated (61.1%, p<0.05) and CP of AD combined with comorbid AtD (52.4%, p<0.05). There were detected the associations of studied SNP with AD: C/T rs_7927894 FLG is significantly directly associated with AD (r=0.291, p<0.05), C/C rs_7927894 FLG has a reverse association with a trend to significance (r=-0.194, p=0.07). Mean serum concentrations of TARC/CCL17 did not differ significantly among patients cohorts of the main and control groups, respectively: general main group — 615.8 pg/ml, main with a CP AD isolated — 651.3 pg/ml, main with a CP of AD combined with comorbid AtD — 585.4 pg/ml, control — 608.4 pg/ml (p>0.05). Associations of serum TARC/CCL17 concentrations were determined as follows: elevation trending to significance within increasing AD severity degree (r=0.290, p=0.07) and significant elevation within the AD exhacerbation period (r=0.426, p<0.05). No significant association of TARC/CCL17 as to AD patients compared to the control group was detected in our study (r=-0.027, p>0.05).

Conclusions. The genotype heterozygote variant C/T rs_7927894 FLG is significantly the most common and associated with all AD CP in children — isolated and combined with comorbid AtD. Variant C/C rs_7927894 of FLG gene is significantly reversely associated with AD in children. Serum concentrations of TARC/CCL17 did not reveal any significant differences between the AD patients and nonEatopic ones. However, they significantly elevate within AD exacerbation phase and trending to significance within AD severity degree increase in children.

The research was carried out in accordance with the principles of the Helsinki declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies.

No conflict of interest was declared by the authors.