Family-based whole exome sequencing of atopic dermatitis complicated with cataracts

Intrinsic Effects of Exposome in Atopic Dermatitis: Genomics, Epigenomics and Regulatory Layers

Atopic dermatitis (AD) or atopic eczema is an increasingly manifested inflammatory skin disorder of complex etiology which is modulated by both extrinsic and intrinsic factors. The exposome includes a person's lifetime exposures and their effects. We recently reviewed the extrinsic exposome's environmental risk factors that contribute to AD. The periods of pregnancy, infancy, and teenage years are recognized as crucial stages in the formation of AD, where the exposome leads to enduring impacts on the immune system. However, research is now focusing on the interactions between intrinsic pathways that are modulated by the extrinsic exposome, including genetic variation, epigenetic modifications, and signals, such as diet, stress, and microbiome interactions. As a result, immune dysregulation, barrier dysfunction, hormonal fluctuations, and skin microbiome dysbiosis are important factors contributing to AD development, and their in-depth understanding is crucial not only for AD treatment but also for similar inflammatory disorders.

Ocular Co-Morbidities of Atopic Dermatitis. Part I: Associated Ocular Diseases

Ocular diseases associated with atopic dermatitis (AD) may be sight-threatening. A general understanding of the pathophysiology, diagnosis, and treatment of atopic eye disease may assist dermatologists in knowing when to refer to ophthalmology and in co-managing these diseases with ophthalmologists. Ocular diseases associated with AD include eyelid dermatitis, keratoconjunctivitis, keratoconus, cataract, and retinal detachment. AD patients are also at higher risk for bacterial and viral ocular infections. The objective of this article is to provide a current review of ocular diseases that commonly affect AD patients. The pathogenesis, clinical manifestations, diagnosis, and treatment of ocular co-morbidities of AD will be discussed.

Genetics of Atopic Dermatitis: From DNA Sequence to Clinical Relevance

Atopic dermatitis (AD) is a complex disease that is thought to be triggered by environmental factors in genetically susceptible individuals. Twin studies have estimated the heritability of AD to be approximately 75%, with the null (loss-of-function) mutations of the gene encoding filaggrin (FLG) (chromosome 1q21.3) as the strongest known genetic risk factor. The discovery of the filaggrin gene was important in the emerging model for AD pathogenesis, combining skin barrier function with adaptive and innate immunity. Assisted by the recent development of large-scale high-throughput genomics, more than 30 genetic loci have been linked to AD across different populations. Identification of these loci, together with functional studies, has already provided new insights into disease biology and identified novel drug targets. Further, these susceptibility loci are laying the groundwork for phenome-wide association studies to test their multiple phenotype relationships and application of Mendelian randomization to investigate causal relationships. Despite many known genes, a majority of the genetic risk for AD is yet unexplored. Therefore, studies investigating refined phenotype groups, low-frequency and rare genetic variation, gene-gene and/or gene-environment interactions, epigenetic mechanisms and data from multi-omics technologies are warranted. In this review, we describe genetic discoveries for AD, including results from candidate gene studies, studies of AD-like genetic diseases, genome-wide association studies and genetic sequencing studies. We explain how some of these genetic discoveries have unraveled new mechanistic insights into the pathogenesis of AD and exemplify how personal genetic data could be used for preventive strategies and a tailored treatment regimen (i.e., precision medicine).

Whole exome sequencing detects novel variants in Saudi children diagnosed with eczema

BACKGROUND

Eczema is also known as atopic dermatitis is well-known for the skin disease globally. In Saudi Arabia, exome sequencing studies have not been documented. The purpose of this study was to scrutinize the disease causing mutations in children affected with eczema with exome sequencing in the Saudi population.

METHODS

We recruited randomly three sporadic cases of children diagnosed with eczema and simultaneously, three more cases were adopted for control samples. Exome sequencing was carried out by applying a pipeline that captures all the variants of concern related to the samples by using the Ion torrent.

RESULTS

In this study, we have documented 49 variants, among which 37 variants were confirmed through eczema children and remaining 30 variants through control children. However, from the analysis of the 6 samples, we have identified rs10192157 (1646C>T; Thr549Ile), rs2899642 (27C>G; Asn9Lys), chr1:152127950 (1625G>A; Gly542Asp) and chr1:152128041 (1534C>G; Gly512Arg) variants which are rarely linked to the disease eczema. In the rs10192157, we have documented these mutations in all three eczema children and one in the control; the rs2899642 mutation appeared in only a couple of eczema children, whereas the mutation in the chr1:152127950 regions appeared in only one eczema patient. However, the chr1:152128041 mutations appeared in only one case of eczema and also in two control children.

CONCLUSION

Our study revealed four mutations which had not previously been connected with eczema within the database. However, the rs10192157 and rs2899642 mutations were documented with asthma disease. The remaining mutations such as chr1:152127950 and chr1:152128041 have not been reported anywhere else. This study recommends screening these 4 mutations in eczema cases and their relevant controls to confirm the prevalence in the Saudi population. It is recommended that future studies examine the 4 mutations in detail.

DNA methylation and allergic sensitizations: A genome-scale longitudinal study during adolescence

BACKGROUND

The presence of allergic sensitization has a major influence on the development and course of common childhood conditions such as asthma and rhinitis. The etiology of allergic sensitization is poorly understood, and its underlying biological mechanisms are not well established. Several studies showed that DNA methylation (DNAm) at some CpGs is associated with allergic sensitization. However, no studies have focused on the critical adolescence period.

METHODS

We assessed the association of pre- and postadolescence genome-wide DNAm with allergic sensitization against indoor, outdoor and food allergens, using linear mixed models. We hypothesized that DNAm is associated with sensitization in general, and with poly-sensitization status, and these associations are age- and gender-specific. We tested these hypotheses in the IoW cohort (n = 376) and examined the findings in the BAMSE cohort (n = 267).

RESULTS

Via linear mixed models, we identified 35 CpGs in IoW associated with allergic sensitization (at false discovery rate of 0.05), of which 33 were available in BAMSE and replicated with respect to the direction of associations with allergic sensitization. At the 35 CpGs except for cg19210306 on C13orf27, a reduction in methylation among atopic subjects was observed, most notably for cg21220721 and cg11699125 (ACOT7). DNAm at cg10159529 was strongly correlated with expression of IL5RA in peripheral blood (P-value = 6.76 × 10^-20 ). Three CpGs (cg14121142, cg23842695, and cg26496795) were identified in IoW with age-specific association between DNAm and allergic sensitization.

CONCLUSION

In adolescence, the status of allergic sensitization was associated with DNAm differentiation and at some CpGs the association is likely to be age-specific.