Gene Polymorphism of Interleukin-4, Interleukin-4 Receptor and STAT6 in Children with Atopic Dermatitis in Taif, Saudi Arabia

Aim of study: This work was performed to evaluate the level of IL-4, and to clarify the role of IL-4 gene polymorphism at position cytosine -590-to-thyamine (C-590T), IL-4Rα gene polymorphism at position adenine +4679-to-guanine (A+4679G) [isoleucine-50-valine (I50V)] and STAT6 gene polymorphism at position guanine 2964-to-adenine (G2964A) in Saudi children with non-atopic dermatitis (non-AD) and atopic dermatitis (AD) to identify their role in the pathogenesis of these diseases.

Subjects and methods: This study included 150 children: 50 healthy children as controls, 50 with non-AD, and 50 with AD. They were subjected to full clinical examination, complete blood picture, skin prick test, and determination of serum interleukin-4 (IL-4) and total immunoglobulin-E (IgE) levels. Detection of interleukin-4 gene (C-590T), interleukin-4 receptor alpha gene (A+4679G) (I50V), and STAT6 gene (G2964A) polymorphisms were performed by PCR-based restriction fragment length polymorphism (PCR-RFLP).

Results: There was a significant (P < 0.01) association between genotype and allele frequencies of IL-4Rα (A+4679G) (I50V) polymorphism in the AD group (but not non-AD group). Moreover, there was a significant association between genotype and allele frequencies of the STAT6 (G2946A) polymorphism in the non-AD (P < 0.05) and AD (P < 0.01) groups. On the other hand, there was no significant association between genotype and allele frequencies of the (C-590T) polymorphism in the non-AD group and AD group. There was a significant (P < 0.001) higher total IgE level in patients compared to the controls. Moreover, the mean values of total IgE were significantly different among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively, in all the studied groups. On the other hand, there was no significant difference of serum IL-4 levels among all the studied patients, or among the different allelic variants of (C-590T), (I50V), (G2964A) polymorphisms of IL-4, IL-4Rα, and STAT6 genes, respectively.

Conclusion: IL-4Rα gene (I50V) and STAT6 gene (G2964) polymorphisms may play a role in development of eczema; however, the IL-4 gene polymorphism (C-590T) had no relationship with susceptibility to the disease among Saudi children.