Diagnosis of Inherited Epidermolysis Bullosa in Resource-Limited Settings: Immunohistochemistry Revisited

A retrospective analysis of diagnostic testing in a large North American cohort of patients with epidermolysis bullosa

BACKGROUND

Accurate diagnosis of epidermolysis bullosa (EB) has significant implications for prognosis, management, and genetic counseling.

OBJECTIVE

To describe diagnostic testing patterns and assess diagnostic concordance of transmission electron microscopy (TEM), immunofluorescence mapping (IFM), and genetic analysis for EB.

METHODS

A retrospective cohort included patients enrolled in the Epidermolysis Bullosa Clinical Characterization and Outcomes Database from January 1, 2004, to July 8, 2019. Tests concluding the same EB type (EB simplex, junctional EB, dominant dystrophic EB, and recessive dystrophic EB) were considered concordant; those concluding different EB types were considered discordant; and those with nonspecific/nondefinitive results were equivocal.

RESULTS

A total of 970 diagnostic tests were conducted from 1984 to 2018 in 771 patients. Genetic analyses were performed chronologically later than IFM or TEM (P < .001). The likelihood of undergoing genetic analysis was greater for junctional EB and recessive dystrophic EB, and the same for dominant dystrophic EB as compared with EB simplex. TEM results in 163 patients were equivocal (55%), concordant (42%), and discordant (3%). IFM results in 185 patients were equivocal (54%), concordant (42%), and discordant (4%).

LIMITATIONS

Retrospective design.

CONCLUSIONS

Diagnostic testing has shifted in favor of genetic analysis. TEM and IFM frequently offer equivocal findings when compared to the specificity afforded by genetic analysis.

Correlating Clinical and Laboratory Diagnostic Modalities in the Diagnosis of Epidermolysis Bullosa in a Resource Poor Setting

BACKGROUND

The mutational analysis along with immunofluorescence antigen mapping (IFM) are recommended as the laboratory tools of choice for diagnosing EB. In the past, transmission electron microscopy (TEM) was considered the gold standard, and more recently, clinical diagnostic matrix (CDM) has shown good concordance with next-generation sequencing (NGS).

MATERIALS AND METHODS

In this prospective diagnostic study, a skin biopsy was taken for TEM and IFM in consecutive patients with EB (aged >6 months) diagnosed clinically with CDM. Wherever possible, mutational analysis was done using targeted NGS.

RESULTS

Of the 80 patients diagnosed with CDM, skin biopsies of 42 patients were assessed using TEM, and of 59 patients using IFM. NGS was done in 39 patients. Taking NGS as the gold standard for diagnosing EB (n = 39 patients), the concordance with CDM, TEM and IFM were estimated at 84.6% (33/39), 78.5% (11/14), and 76% (19/25) respectively. CDM showed a substantial agreement with NGS (k = 0.69, P < 0.001).

CONCLUSIONS

In comparison to NGS, the highest concordance was seen with CDM followed by TEM and IFM in diagnosing major subtypes of EB. This article is protected by copyright. All rights reserved.

Epidermolysis Bullosa: Pediatric Perspectives

Epidermolysis bullosa (EB) is a group of rare congenital genetic conditions that result in painful blistering of the skin and mucous membranes, which occur with minor trauma or friction. There are many types and subtypes of EB that need to be distinguished, as the management and prognosis of each can vary significantly. We aim to perform an up-to-date literature review on congenital EB for healthcare providers in pediatrics. We performed a review of existing literature in the English language on EB via PubMed Clinical Queries, using key words such as "epidermolysis bullosa", "congenital" and "children". We reviewed EB based on the following subheadings: epidemiology, diagnosis, therapy, prognosis, and clinical prediction guidelines. EB is due to mutation in a number of genes, some types are autosomal dominant while others are autosomal recessive. The underlying mechanism is a defect in attachment between or within the epidermis and dermis of the skin. There are four main types: epidermolysis bullosa simplex, dystrophic epidermolysis bullosa, junctional epidermolysis bullosa, and Kindler syndrome. The diagnosis is suspected based on symptoms and confirmed by skin biopsy and definitive genetic testing. The severity of EB can range from mild to fatal. Severe complications may arise in some EB types and subtypes within the eye, ear, nose, upper airway, gastrointestinal and genitourinary tracts. There is no cure for the condition to date. Optimal management must be multidisciplinary, and involves wound care, pain control, controlling infections, nutritional support, and prevention and treatment of complications. EB presents in different forms. Treatment is supportive. The prognosis of milder forms is good. Children severely affected with EB and their families live a misery life with impaired quality of life. Health care workers must be aware of the suffering in these families and proactively support them.

The severity of malnutrition in children with epidermolysis bullosa correlates with disease severity

WHO defines malnutrition as severe if the z-scores are less than - 3 Standard deviation (SD), moderate if between - 2 and - 3 SD and mild if between - 2 SD to - 1 SD. This study was aimed to assess nutritional aspects of Indian children suffering from EB and to evaluate the effect of severity of EB on the severity of malnutrition. In this study, pediatric EB patients were evaluated prospectively for baseline nutritional status using anthropometric parameters and WHO growth charts, and its correlation with disease severity using instrument for Scoring Clinical Outcomes for Research of Epidermolysis Bullosa-iscorEB. In second phase, an individualized diet chart was given to meet the energy, protein and micronutrients needs and its effects were observed after 6 months. The median age of participants was 3 years (IQR-9). Of 57 patients, malnutrition was seen in 40.35% patients (22.81%-moderate and 17.54%-severe), and significantly correlated with iscorEB (r = 0.45, p < 0.0001). On bivariate regression analysis, iscorEB was independently associated with moderate-to-severe malnutrition (p = 0.047; OR 1.038, CI 1.011-1.066). iscorEB enabled the identification of patients with moderate-to-severe malnutrition with an Area Under Receiver Operating Curve (AUROC) of 0.72 (95%CI 0.58-0.85; p < 0.005). In phase 2, there was significant improvement in nutritional status in children with recessive dystrophic EB (RDEB) and dominant dystrophic EB (DDEB) subtype (p < 0.0001). The severity of malnutrition in EB children significantly correlates with disease severity, and is an independent predictor of moderate-to-severe malnutrition.

Whole Exome Sequencing Confirms Molecular Diagnostics of Three Pakhtun Families With Autosomal Recessive Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a genetic skin disorder that shows heterogeneous clinical fragility. The patients develop skin blisters congenitally or in the early years of life at the dermo-epithelial junctions, including erosions, hyperkeratosis over the palms and soles. The other associated features are hypotrichosis on the scalp, absent or dystrophic nails, and dental anomalies. Molecular diagnosis through whole-exome sequencing (WES) has become one of the successful tool in clinical setups. In this study, three Pakhtun families from the Khyber Pakhtunkhwa province of Pakistan were ascertained. WES analysis of a proband in each family revealed two novel variants (COL17A1: NM_000494.4: c.4041T>G: p.Y1347^* and PLEC: NM_201380.3: c.1283_1285delGCT: p.L426del) and one previously known COL17A1: NM_000494.4:c.3067C>T: p.Q1023^*) variant in homozygous forms. Sanger sequencing of the identified variants confirmed that the heterozygous genotypes of the obligate carriers. The identified variants have not only increased the mutation spectrum of the COL17A1 and PLEC but also confirms their vital role in the morphogenesis of skin and its associated appendages. WES can be used as a first-line diagnostic tool in genetic testing and counselling families from Khyber Pakhtunkhwa, Pakistan.

Clinical practice guidelines for laboratory diagnosis of epidermolysis bullosa

Linked Comment: https://doi.org/10.1111/bjd.18377.

https://doi.org/10.1111/bjd.18829 available online

Inherited Epidermolysis Bullosa – A Case Report of Several Family Members in Three Generations

Inherited epidermolysis bullosa (IEB) is a genodermatosis transmitted in either autosomal dominant or autosomal recessive manner. The disease is characterized by the development of blisters, erosions, scars, nail dystrophy and scalp abnormalities. Our case report has included four members of one family in three generations with manifested disease. Our 25-year-old female patient presented with a few eroded, crusted, nummular lesions localized on the dorsal plate of interphalangeal joints of fingers, elbow and knee skin, while anonychia was found on her digits. Our youngest patient (her 3.5-year-old son) presented with the lesions in the form of blisters filled with serous fluid, erosions, recent scars and atrophy. Some atrophic scars on the elbow and knee skin were found in our patient′s younger brother, aged 16. The 46-year-old mother of our female patient had nail dystrophy on her hands accompanied by the toenails absence. Pediatric geneticist created the pedigree chart which showed autosomal dominant inheritance pattern with complete expressivity and penetrance. Further diagnostics was not done because the family was not interested.