Association of beta-defensin 1 single nucleotide polymorphism with atopic dermatitis

Atopic dermatitis (AD) is a chronic relapsing, pruritic, inflammatory skin disease, which results from a complex interplay between genetic and environmental factors. Defensins are broadly dispersed family of antimicrobial peptides which are classified into 2 distinct families: the alpha-defensins and the beta-defensins. The primary function of defensins is to protect the skin from invasion by foreign pathogens. Previous studies suggested that single nucleotide polymorphisms (SNPs) of the beta-defensin 1 gene (DEFB1) could be involved in the development of AD. The Aim of the study is to examine DEFB1 gene to gain a better understanding of their role in the pathophysiology of AD patients and their involvement in AD susceptibility and severity. 35 atopic patients and 10 healthy volunteers as controls were investigated. They were subjected to analysis of absolute eosinophil count, total and specific IgE and detection of Beta-defensin-1 gene polymorphism at position 692 and 1654 using PCR amplification and restriction analysis. We observed significant difference in the distribution of the DEFB1 AIG polymorphism at 692 (P<0.01) in AD patients compared to controls, but not at 1654. A statistical significant association between DEFB1 692 GG genotype and elevated total serum IgE level (P<0.01), and between DEFB1 692 GG and AG genotypes & 1654 AA genotype and high absolute eosinophil count (P<0.05) were found. Concerning Specific IgE there was significant association between DEFB1 692 GG genotype and positive specific IgE to dermatophytes and HDM (House Dust Mite) (P1<0.01) while DEFB1 1654AA genotype shows significant association with positive specific IgE to cockroaches (P<0.05). Regarding SCORAD severity index, there was significant statistical association between DEFB1 692 GG and AG & DEFB1 1654 AA and AG genotype with severe AD disease (P<0.05). The correlation between atopic markers and SCORAD severity index shows that there was a significant statistical relationship between serum levels of total IgE (P<0.01), absolute eosinophil count (P<0.01), specific IgE to cat (P<0.05), HDM (P<0.01) and cockroaches (P<0.01) and SCORAD. Our findings support previously studies suggesting that DEFB1 gene is one of the candidate genes for atopy. G allele at site 692& AA genotype at site 1654 may be useful as markers for AD susceptibility and severity