Whole-Exome Sequencing in Patients Affected by Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis Reveals New Variants Potentially Contributing to the Phenotype

A bioinformatic approach to identify pathogenic variants for Stevens-Johnson syndrome

Stevens-Johnson syndrome (SJS) produces a severe hypersensitivity reaction caused by Herpes simplex virus or mycoplasma infection, vaccination, systemic disease, or other agents. Several studies have investigated the genetic susceptibility involved in SJS. To provide further genetic insights into the pathogenesis of SJS, this study prioritized high-impact, SJS-associated pathogenic variants through integrating bioinformatic and population genetic data. First, we identified SJS-associated single nucleotide polymorphisms from the genome-wide association studies catalog, followed by genome annotation with HaploReg and variant validation with Ensembl. Subsequently, expression quantitative trait locus (eQTL) from GTEx identified human genetic variants with differential gene expression across human tissues. Our results indicate that two variants, namely rs2074494 and rs5010528, which are encoded by the HLA-C (human leukocyte antigen C) gene, were found to be differentially expressed in skin. The allele frequencies for rs2074494 and rs5010528 also appear to significantly differ across continents. We highlight the utility of these population-specific HLA-C genetic variants for genetic association studies, and aid in early prognosis and disease treatment of SJS.

Chronic ocular sequelae in Stevens-Johnson syndrome: a genetic association study

Purpose

This study sought to investigate the association of molecular markers with chronic ocular sequelae in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN).

Methods

One hundred SJS/TEN patients (200 eyes) with confirmed diagnosis were enrolled between July 2011 and July 2015 from a tertiary eye-care hospital, and their clinical histories were noted. Each eye was scored for severity of manifestation on a scale of 0-5. Peripheral blood samples were collected for DNA followed by screening for interleukin (IL-4, IL-13, IL-4R) polymorphisms, HLA-A locus allele typing, and sera to detect levels of the apoptotic markers granulysin and sFas L.

Results

Of the 100 enrolled patients (53 males/47 females; age range: 6-58 years), the incriminating drugs were non-steroidal anti-inflammatory (52%), antibiotics (10%), sulphonamides (8%), anti-epileptics (6%), and unknown (24%). Significant differences in the frequencies of IL-4R polymorphism, HLA-A*3301, HLA-A*02, and HLA-A*2402 alleles, and elevated levels of granulysin and sFas L were observed in patients compared to controls. The ocular complications of conjunctival keratinization (p=0.004) showed an association with IL-13 promoter region (IL-13a) genotypes.

Conclusions

The study highlights the possible association of interleukin-13 with severity-graded chronic sequelae and the role of HLA-A alleles- HLA-A*3301, HLA-A*02, and HLA-A*2402 in SJS/TEN causation and manifestation. Screening of these alleles may help caregivers to identify markers associated with severe and lifelong ocular complications, and help in appropriate treatment and management of the condition.

Genophenotypic Factors and Pharmacogenomics in Adverse Drug Reactions

Adverse drug reactions (ADRs) rank as one of the top 10 leading causes of death and illness in developed countries. ADRs show differential features depending upon genotype, age, sex, race, pathology, drug category, route of administration, and drug–drug interactions. Pharmacogenomics (PGx) provides the physician effective clues for optimizing drug efficacy and safety in major problems of health such as cardiovascular disease and associated disorders, cancer and brain disorders. Important aspects to be considered are also the impact of immunopharmacogenomics in cutaneous ADRs as well as the influence of genomic factors associated with COVID-19 and vaccination strategies. Major limitations for the routine use of PGx procedures for ADRs prevention are the lack of education and training in physicians and pharmacists, poor characterization of drug-related PGx, unspecific biomarkers of drug efficacy and toxicity, cost-effectiveness, administrative problems in health organizations, and insufficient regulation for the generalized use of PGx in the clinical setting. The implementation of PGx requires: (i) education of physicians and all other parties involved in the use and benefits of PGx; (ii) prospective studies to demonstrate the benefits of PGx genotyping; (iii) standardization of PGx procedures and development of clinical guidelines; (iv) NGS and microarrays to cover genes with high PGx potential; and (v) new regulations for PGx-related drug development and PGx drug labelling.