The study of filaggrin gene mutations and copy number variation in atopic dermatitis patients from Volga-Ural region of Russia

Association between polymorphisms and atopic dermatitis susceptibility: A systematic review and meta-analysis

AIM

Atopic dermatitis (AD) is a chronic pruritic inflammatory skin disease that is closely linked to genetic factors. Previous studies have revealed numerous single nucleotide polymorphisms (SNPs) that been related to susceptibility to AD; however, the results are conflicting. Therefore, a meta-analysis was conducted to assess the associations of these polymorphisms and AD risk.

MATERIAL AND METHODS

PubMed, Web of Science, Embase, Cochrane Library, and China National Knowledge Infrastructure databases were retrieved to identify eligible studies, with selected polymorphisms being reported in a minimum of three separate studies. The Newcastle-Ottawa Scale (NOS) was used to evaluate study quality. Review Manager 5.3 and STATA 14.0 were used to perform the meta-analysis.

RESULTS

After screening, 64 studies involving 13 genes (24 SNPs) were selected for inclusion in the meta-analysis. Nine SNPs were positively correlated with AD susceptibility [filaggrin (FLG) R501X, FLG 2282del4, chromosome 11q13.5 rs7927894, interleukin (IL)-17A rs2275913, IL-18 -137 G/C, Toll-like receptor 2 (TLR2) rs5743708, TLR2 A-16934 T, serine protease inhibitor Kazal type-5 (SPINK5) Asn368Ser, interferon-γ (IFN-γ) T874A] and one was negatively associated with AD susceptibility (IL-4 -1098 T/G). The 14 remaining SNPs were not significantly associated with AD susceptibility.

CONCLUSIONS

Nine SNPs that may be risk factors and one SNP that may be a protective factor for AD were identified, providing a reference for AD prediction, prevention, and therapy.

Candidate Gene Association Studies in Atopic Dermatitis in Participants of European and Asian Ancestry: A Systematic Review and Meta-Analysis

Atopic dermatitis (AD) has been extensively investigated for genetic associations utilizing both candidate gene approaches and genome-wide scans. Here, we comprehensively evaluated the available literature to determine the association of candidate genes in AD to gain additional insight into the etiopathogenesis of the disease. We systematically screened all studies that explored the association between polymorphisms and AD risks in cases of European and Asian ancestry and synthesized the available evidence through a random-effects meta-analysis. We identified 99 studies that met our inclusion/exclusion criteria that examined 17 candidate loci in Europeans and 14 candidate genes in Asians. We confirmed the significant associations between FLG variants in both European and Asian populations and AD risk, while synthesis of the available data revealed novel loci mapped to IL18 and TGFB1 genes in Europeans and IL12RB1 and MIF in Asians that have not yet been identified by genome-wide association studies. Our findings provide comprehensive evidence for AD risk loci in cases of both European and Asian ancestries, validating previous associations as well as revealing novel loci that could imply previously unexplored biological pathways.

Filaggrin gene mutations with special reference to atopic dermatitis

Purpose of review

Mutations in the Filaggrin gene can cause absent or reduced filaggrin protein, leading to impaired keratinization and skin barrier defect, which produce characteristic phenotypes. In this short review, we report current evidence on the topic with special reference to atopic dermatitis, suggest future directions, and discuss therapeutic implications.

Recent findings

Numerous candidate gene association studies, genome-wide association studies, studies on copy number variations and most recently, sequencing studies, have confirmed the robust association of mutations in the Filaggrin gene with atopic dermatitis, and have also linked these mutations with several other disorders.

Summary

Filaggrin gene defects remain the strongest identified genetic risk factors for atopic dermatitis. Taken in conjunction with other genes found to be associated with this condition, genetic screening and identification of individuals at risk for atopic dermatitis could lead to personalized therapy. Manipulation of genetic regulatory elements to increase the amount of filaggrin protein in deficient individuals is an attractive treatment option for the future.

Genetics and Epigenetics of Atopic Dermatitis: An Updated Systematic Review

BACKGROUND

Atopic dermatitis is a common inflammatory skin disorder that affects up to 15-20% of the population and is characterized by recurrent eczematous lesions with intense itching. As a heterogeneous disease, multiple factors have been suggested to explain the nature of atopic dermatitis (AD), and its high prevalence makes it necessary to periodically compile and update the new information available. In this systematic review, the focus is set at the genetic and epigenetic studies carried out in the last years.

METHODS

A systematic literature review was conducted in three scientific publication databases (PubMed, Cochrane Library, and Scopus). The search was restricted to publications indexed from July 2016 to December 2019, and keywords related to atopic dermatitis genetics and epigenetics were used.

RESULTS

A total of 73 original papers met the inclusion criteria established, including 9 epigenetic studies. A total of 62 genes and 5 intergenic regions were described as associated with AD.

CONCLUSION

Filaggrin (FLG) polymorphisms are confirmed as key genetic determinants for AD development, but also epigenetic regulation and other genes with functions mainly related to the immune system and extracellular matrix, reinforcing the notion of skin homeostasis breakage in AD.