Homozygous ITGA3 Missense Mutation in Adults in a Family with Syndromic Epidermolysis Bullosa (ILNEB) Without Pulmonary Involvement

Integrin mutations in blistering skin diseases and related genetically engineered mouse models

As major receptors for cellular adhesion, integrins in the epidermis are critical to maintain skin integrity. Integrins α6β4 and α3β1 are among the most highly and widely expressed integrins in the skin. Perhaps not surprisingly, mutation in subunits associated with these integrins cause variations of a blistering skin disease called junctional epidermolysis bullosa (JEB), which is characterized by blisters that form between the epidermis and dermis of the skin. This review highlights how the differences in structural roles and functions for these epidermal integrins lead to distinct JEB phenotypes resulting from their absence. Additionally, much has been learned by using genetically engineered mouse models, which are featured throughout the review, as they closely resemble the disorders of human patients that harbor analogous mutations.

Roles for epithelial integrin α3β1 in regulation of the microenvironment during normal and pathological tissue remodeling

Integrin receptors for the extracellular matrix activate intracellular signaling pathways that are critical for tissue development, homeostasis, and regeneration/repair, and their loss or dysregulation contributes to many developmental defects and tissue pathologies. This review will focus on tissue remodeling roles for integrin α3β1, a receptor for laminins found in the basement membranes (BMs) that underlie epithelial cell layers. As a paradigm, we will discuss literature that supports a role for α3β1 in promoting ability of epidermal keratinocytes to modify their tissue microenvironment during skin development, wound healing, or tumorigenesis. Preclinical and clinical studies have shown that this role depends largely on ability of α3β1 to govern the keratinocyte's repertoire of secreted proteins, or the "secretome," including 1) matrix proteins and proteases involved in matrix remodeling and 2) paracrine-acting growth factors/cytokines that stimulate other cells with important tissue remodeling functions (e.g., endothelial cells, fibroblasts, inflammatory cells). Moreover, α3β1 signaling controls gene expression that helps epithelial cells carry out these functions, including genes that encode secreted matrix proteins, proteases, growth factors, or cytokines. We will review what is known about α3β1-dependent gene regulation through both transcription and posttranscriptional mRNA stability. Regarding the latter, we will discuss examples of α3β1-dependent alternative splicing (AS) or alternative polyadenylation (APA) that prevents inclusion of cis-acting mRNA sequences that would otherwise target the transcript for degradation via nonsense-mediated decay or destabilizing AU-rich elements (AREs) in the 3'-untranslated region (3'-UTR). Finally, we will discuss prospects and anticipated challenges of exploiting α3β1 as a clinical target for the treatment of cancer or wound healing.

Clinical and molecular diagnosis of genodermatoses: Review and perspectives

Genodermatoses are a complex and heterogeneous group of genetic skin disorders characterized by variable expression and clinical and genetic heterogeneity, rendering their diagnosis challenging. DNA-based techniques, like whole-exome sequencing, can establish a diagnosis in 50% of cases. RNA-sequencing is emerging as an attractive tool that can obtain information regarding gene expression while integrating functional genomic data with regard to the interpretation of variants. This increases the diagnostic rate by an additional 10-15%. In the present review, we detail the clinical steps involved in the diagnosis of genodermatoses, as well as the current DNA-based technologies available to clinicians. Herein, the intention is to facilitate a better understanding of the possibilities and limitations of these diagnostic technologies. In addition, this review could guide dermatologists through new emerging techniques, such as RNA-sequencing and its applications to familiarizing them with future techniques. Currently, this multi-omics approach is likely the best strategy designed to promote the diagnosis of patients with genodermatoses and discover new skin disease genes that could result in novel targeted therapies.

Epidermolysis Bullosa—A Different Genetic Approach in Correlation with Genetic Heterogeneity

Epidermolysis bullosa is a heterogeneous group of rare genetic disorders characterized by mucocutaneous fragility and blister formation after minor friction or trauma. There are four major epidermolysis bullosa types based on the ultrastructural level of tissue cleavage: simplex, junctional, dystrophic, and Kindler epidermolysis bullosa. They are caused by mutations in genes that encode the proteins that are part of the hemidesmosomes and focal adhesion complex. Some of these disorders can be associated with extracutaneous manifestations, which are sometimes fatal. They are inherited in an autosomal recessive or autosomal dominant manner. This review is focused on the phenomena of heterogeneity (locus, allelic, mutational, and clinical) in epidermolysis bullosa, and on the correlation genotype–phenotype.

Biallelic Missense Mutations in the Integrin Alpha 3 Gene Causes Skin Fragility Without Structural Defects in Lungs and Kidneys

Abstract is missing (Short communication)

A novel ITGA3 homozygous splice mutation in an ILNEB syndrome child with slow progression

BACKGROUND AND AIMS

ILNEB (interstitial lung disease, nephrotic syndrome, epidermolysis bullosa) syndrome is caused by ITGA3 mutations. Demises usually happened at infancy. This study reports a complete ILNEB syndrome child with slow disease progression.

MATERIALS AND METHODS

Clinical data and related specimens were collected. Genomic DNA was extracted for genetic sequencing. Integrin α3 expression was detected by western blotting and immunofluorescence staining.

RESULTS

The patient was male. He experienced recurrent rashes shortly after birth. His sparse eyebrows and eyelashes gradually lost. The patient was vulnerable to respiratory infections and had recurrent fever after vaccine immunization after 4 years. He was found with nephrotic syndrome and polycystic renal dysplasia at 8 years and progressed to end-stage renal disease at 12 years. A chest Computed Tomography revealed intestinal lung disease at 8 years. Continuous oxygen supplementation was needed at 13 years. Counts of lymphocyte subsets revealed elevated percentage of double-negative T cells and activated T cells. Next-generation sequencing revealed a novel homozygous splice mutation c.2219 + 4A > Cin ITGA3 that was predicted to be deleterious. The mutation resulted in exon17 skipping with the loss of 80 bp in the mRNA. The aberrant integrin α3 mRNA level was lower compared to the healthy control. Integrin α3 protein was not detected in urine epithelial cells and skin of the patient.

CONCLUSIONS

We report a patient harboring a novel ITGA3 homozygous splice mutation who presented with complete ILNEB syndrome but slow disease progression. Immune disorders were suspected.