Evolution of genome diagnostics in epidermolysis bullosa: Unveiling the power of next-generation sequencing.

BACKGROUND: Genome diagnostics is considered gold standard diagnostics for epidermolysis bullosa (EB), a phenotypically and genetically heterogeneous group of rare disorders characterized by blistering and wounding of mucocutaneous tissues. EB is caused by pathogenic variants in genes encoding proteins of the dermo-epidermal junction. Accurate genetic diagnosis of EB is crucial for prognostication, counselling and precision-medicine. Genome diagnostics for EB started in 1991 with the introduction of Sanger sequencing (SS), analysing one gene at a time. In 2013, SS was superseded by next-generation sequencing (NGS), that allow for high-throughput sequencing of multiple genes in parallel. Several studies have shown a beneficial role for NGS in EB diagnostics, but its true benefit has not been quantified. OBJECTIVES: To determine the benefit of NGS in EB by systematically evaluating the performance of different genome diagnostics used over time based on robust data from the Dutch EB Registry. METHODS: The diagnostic performances of SS and NGS were systematically evaluated in a retrospective observational study including all index cases with a clinical diagnosis of EB in whom genome diagnostics was performed between 01 January 1994 and 01 January 2022 (n = 308), registered at the Dutch EB Expertise Centre. RESULTS: Over time, a genetic diagnosis was made in 289/308 (94%) EB cases. The diagnostic yield increased from 89% (SS) to 95% (NGS). Most importantly, NGS significantly reduced diagnostic turnaround time (39 days vs. 211 days, p < 0.001). The likelihood of detecting variants of uncertain significance and additional findings increased from 5% and 1% (SS) to 22% and 13% (NGS) respectively. CONCLUSIONS: Our study quantifies the benefit of NGS-based methods and demonstrate they have had a major impact on EB diagnostics through an increased diagnostic yield and a dramatically decreased turnaround time (39 days). Although our diagnostic yield is high (95%), further improvement of genome diagnostics is urgently needed to provide a genetic diagnosis in all EB patients.

Pathogenic neurofibromatosis type 1 (NF1) RNA splicing resolved by targeted RNAseq.

Neurofibromatosis type 1 (NF1) is caused by loss-of-function variants in the NF1 gene. Approximately 10% of these variants affect RNA splicing and are either missed by conventional DNA diagnostics or are misinterpreted by in silico splicing predictions. Therefore, a targeted RNAseq-based approach was designed to detect pathogenic RNA splicing and associated pathogenic DNA variants. For this method RNA was extracted from lymphocytes, followed by targeted RNAseq. Next, an in-house developed tool (QURNAs) was used to calculate the enrichment score (ERS) for each splicing event. This method was thoroughly tested using two different patient cohorts with known pathogenic splice-variants in NF1. In both cohorts all 56 normal reference transcript exon splice junctions, 24 previously described and 45 novel non-reference splicing events were detected. Additionally, all expected pathogenic splice-variants were detected. Eleven patients with NF1 symptoms were subsequently tested, three of which have a known NF1 DNA variant with a putative effect on RNA splicing. This effect could be confirmed for all 3. The other eight patients were previously without any molecular confirmation of their NF1-diagnosis. A deep-intronic pathogenic splice variant could now be identified for two of them (25%). These results suggest that targeted RNAseq can be successfully used to detect pathogenic RNA splicing variants in NF1.

Recessive mosaicism in ABCA12 causes blaschkoid congenital ichthyosiform erythroderma.

We report the unique case of a 3-year-old girl who presented with linear erythematosquamous lesions following the lines of Blaschko, suggestive of genetic mosaicism in the skin. Single-candidate gene analyses were performed on DNA from blood, excluding Conradi-Hünermann-Happle syndrome, erythrokeratodermia variabilis and a mosaic presentation of pityriasis rubra pilaris. With whole-exome sequencing (WES) on DNA from the patient's blood, a heterozygous missense mutation in exon 25 of the ABCA12 gene was detected. By manually scrutinizing the WES data, another low-percentage pathogenic frameshift mutation was found in the adjacent exon 26 of the same gene. This frameshift mutation was confirmed with Sanger sequencing in DNA isolated from a lesional skin biopsy. A subsequent cloning experiment was performed to prove that the patient is compound heterozygous for both mutations in the affected skin, explaining the blaschkoid ichthyosiform erythrodermic phenotype. The patient's phenotype was elucidated by the combination of a germline mutation and an acquired postzygotic mutation in ABCA12, resulting in the diagnosis of a mosaic manifestation of autosomal recessive congenital ichthyosis. Postzygotic compound allelic loss in autosomal recessive disorders is extremely rare and will not appear as the typical phenotype of the known germline mutation-associated disease. This is the first report of a proven biallelic mosaic presentation of an autosomal recessive genodermatosis, and we propose the term 'recessive mosaicism' for this kind of manifestation. What's already know about this topic? Specific mutations in the ABCA12 lipid transporter are known to cause different phenotypes like harlequin ichthyosis, congenital ichthyosiform erythroderma and lamellar ichthyosis. In mosaicism, two or more cell populations that are genetically different arise postzygotically in the developing embryo. In the skin, mosaicism can present itself in different patterns of affected skin, often caused by a dominant genetic mutation. What does this study add? We report a unique patient with blaschkoid congenital ichthyosiform erythroderma due to biallelic mutations, one inherited germline missense mutation and the other a postzygotic frameshift mutation in the ABCA12 gene. This study describes the diagnostic approach and applied research that can be used if one encounters a similar diagnostic dilemma with manifestations suspected for genetic mosaicism. We propose the term 'recessive mosaicism' for this kind of mosaic presentation of an autosomal recessive genodermatosis.

Schnitzler's syndrome - a novel hypothesis of a shared pathophysiologic mechanism with Waldenström's disease.

Schnitzler's syndrome is an auto-inflammatory disorder which is characterized by two mandatory features: an urticarial rash and a monoclonal gammopathy. Although the pathophysiology of this syndrome is not yet fully understood, a role for interleukin-1 seems apparent. While this presumed link between interleukin-1 and the monoclonal gammopathy is not yet elucidated, a mutual factor in pathophysiology however seems likely. Here we present a novel hypothesis of a shared pathophysiologic mechanism between Schitzler's syndrome and monoclonal gammopathy.

Genetic profiling of basal cell carcinomas detects postzygotic mosaicism in basal cell naevus syndrome.

Basal cell naevus syndrome (BCNS) is associated with germline mutations in the PTCH1 gene. Postzygotic mosaicism can also cause BCNS. Here we describe two patients, one with multiple basal cell carcinomas (BCCs) and one with clinical BCNS, who had no PTCH1 mutation in DNA extracted from blood. In both patients, we performed genetic analysis on different BCCs, revealing the presence of a shared PTCH1 mutation in all tumours. Our findings show that in patients with symptoms of BCNS and initial absence of a PTCH1 mutation in blood, genetic profiling of BCCs can detect postzygotic mosaicism. What's already known about this topic? Basal cell naevus syndrome (BCNS) is associated with germline mutations in the PTCH1 gene, but it can also be caused by low-grade postzygotic mosaicism in PTCH1. What does this study add? In patients suspected of having BCNS or patients with multiple basal cell carcinomas (BCCs) with a special distribution on the body and no mutation detected in blood, it is worthwhile to search for a shared PTCH1 mutation in their BCCs as this can detect postzygotic mosaicism. This information is important to ensure proper surveillance programmes, choose the right therapy and provide adequate genetic counselling.

Postzygotic mosaicism in basal cell naevus syndrome.

Basal cell naevus syndrome (BCNS) is an autosomal dominant disorder most commonly caused by a germline mutation in the Drosophila homologue of patched-1 gene (PTCH1). Here we describe a patient with clinical signs of BCNS, caused by postzygotic mosaicism of a PTCH1 mutation. We performed restriction fragment length polymorphism analysis and Droplet Digital polymerase chain reaction to determine the degree of mosaicism in different tissues of this patient. Our case shows that a relatively low-grade mosaicism can lead to clinical signs reminiscent of those caused by a germline mutation. This finding has important implications for genetic counselling and therefore is pivotal to recognize for dermatologists, as well as for clinical geneticists and clinical laboratory geneticists.

Validation of the Simplified Psoriasis Index in Dutch children and adolescents with plaque psoriasis.

BACKGROUND: The Simplified Psoriasis Index (SPI) is a three-domain assessment measure for psoriasis, including separate indicators of current severity (SPI-s), psychosocial impact (SPI-p), and past history and interventions (SPI-i). There are two complementary versions available designed for completion by a health professional (proSPI) or by patient self-assessment (saSPI). The validity and reliability of the proSPI vs. saSPI have already been demonstrated in adults. To date, validated severity measures for paediatric psoriasis do not exist. OBJECTIVES: To validate the current severity (SPI-s) and psychosocial impact (SPI-p) domains of the proSPI and saSPI in children and adolescents with psoriasis. METHODS: All patients aged < 18 years with plaque psoriasis visiting the dermatology outpatient department of Radboud University Medical Center, the Netherlands, between September 2013 and April 2014 were asked to complete Dutch versions of the saSPI and the Children's Dermatology Life Quality Index (CDLQI). The original English versions of the proSPI and Psoriasis Area and Severity Index (PASI) were completed by the physician at the same visit. RESULTS: In total, 113 patients (median age 12·0 years, range 4-17) were included. There was a close correlation between the proSPI-s and PASI (r = 0·87), which was higher than between the saSPI-s and PASI (r = 0·69). The correlation between the SPI-p and CDLQI was 0·78. The full range of scores was utilized in both proSPI-s and SPI-p, although the highest saSPI-s score was 30 (maximum 50). CONCLUSIONS: In paediatric psoriasis, the proSPI and saSPI are shown to be valid and usable. The SPI-s and SPI-p can be readily introduced into routine clinical practice.

Comparison of the Dermatology Life Quality Index and the Children's Dermatology Life Quality Index in assessment of quality of life in patients with psoriasis aged 16-17 years.

BACKGROUND: Dermatology Life Quality Index (DLQI) and Children's Dermatology Life Quality Index (CDLQI) are widely used to assess quality of life (QoL) in adults (≥ 16 years) and children (4-16 years) with psoriasis. In the age group 16-17 years, it is not known whether DLQI and CDLQI reflect QoL impairment in the same way. OBJECTIVES: To compare DLQI and CDLQI scores in patients with psoriasis aged 16-17 years. METHODS: Patients with psoriasis aged 16-17 years were asked to complete both the DLQI and CDLQI. RESULTS: Fifty-six patients were included. There was a high correlation between DLQI and CDLQI scores (r = 0·90, P < 0·001). The mean DLQI score (5·41 ± 5·20) was lower than the mean CDLQI (6·61 ± 5·74) (P < 0·001). The major part of this difference (∆0·61) was caused by the low score regarding sexual difficulties in the DLQI (0·11 ± 0·49) and the high score concerning sleep in the CDLQI (0·71 ± 0·93). In addition, the question related to sports scored 0·34 in the DLQI but 0·86 in the CDLQI (∆0·52). The question related to work/study in the DLQI scored lower than the question on school/holiday in the CDLQI (∆0·41). CONCLUSIONS: In patients with psoriasis aged 16-17 years, DLQI and CDLQI scores closely correlate, but the mean DLQI score was lower than the mean CDLQI score. This was caused primarily by differences in the answers to questions regarding sexual difficulties and sleep. As the QoL impacts experienced by people aged 16-17 may differ from those experienced by children or adults, QoL measures designed for use in this age range may have advantages over both child- and adult-specific measures.

Fumaric acid esters in recalcitrant pediatric psoriasis: A prospective, daily clinical practice case series.

BACKGROUND: Evidence on fumaric acid esters (FAE) in the treatment of pediatric psoriasis is scarce. OBJECTIVE: Describe the effectiveness, influence on the quality of life (QoL) and safety of FAE in children with recalcitrant psoriasis in daily clinical practice. METHODS: A prospective case series. RESULTS: Fourteen patients with recalcitrant plaque-type psoriasis were described (mean age 13.7, range 8-17 years). Mean treatment duration was 48.6 weeks (range 12-124). Maximum daily dose varied between 180 and 1200 mg with a mean of 564 mg per day. Mean Psoriasis Area and Severity Index (PASI) (±SEM) at baseline was 10.5 (1.0) compared to 8.6 (1.1), 6.2 (1.6) and 4.9 (1.5) at week 12, 24 and 36, respectively. An improvement in PASI was observed in nine patients (64.3%). Mean CDLQI (±SEM) at week 0, 12, 24 and 36 was 8.9 (1.4), 6.8 (1.2), 3.7 (1.4) and 3.1 (2.0), respectively. Most common adverse events (AEs) were gastrointestinal complaints (n = 13, 92.9%) and flushes (n = 10, 71.4%). Lymphocytopenia (n = 5, 45.5%) and eosinophilia (n = 4, 36.4%) were frequently observed laboratory abnormalities. AEs were usually mild and transient. One serious adverse event, unrelated to FAE, was reported. CONCLUSIONS: FAE showed improvement of disease severity and QoL in the majority of children. Side-effects occurred frequently, but were usually mild and transient. FAE may be an alternative systemic treatment option for pediatric psoriasis, provided that also the long-term safety data are closely monitored, in particular lymphocytopenia.

Psoriasis in Children and Adolescents: Diagnosis, Management and Comorbidities.

Psoriasis is a common chronic immune-mediated inflammatory skin disorder and begins in childhood in almost one-third of the cases. Although children present with the same clinical subtypes of psoriasis seen in adults, lesions may differ in distribution and morphology, and their clinical symptoms at presentation may vary from those reported by adult patients. Nevertheless, diagnosis of psoriasis is primarily based on clinical features. Pediatric psoriasis can have a profound long-term impact on the psychological health of affected children. Additionally, pediatric psoriasis has been associated with certain comorbidities, such as obesity, hypertension, hyperlipidemia, diabetes mellitus and rheumatoid arthritis, making early diagnosis and management essential. As guidelines are lacking and most (systemic) treatments are not approved for use in children, treatment of pediatric psoriasis remains a challenge. A prospective, multicenter, international registry is needed to evaluate these treatments in a standardized manner and ultimately to develop international guidelines on pediatric psoriasis. This article reviews current concepts in pediatric psoriasis including epidemiology, clinical features, diagnosis, the role of topical and systemic agents and the association with other morbidities in childhood.

A pilot study on the Psoriasis Area and Severity Index (PASI) for small areas: Presentation and implications of the Low PASI score.

BACKGROUND: The Psoriasis Area and Severity Index (PASI) is not able to measure small affected areas in a body region which is important for assessing the performance of high-effective treatment. OBJECTIVE: To present the Low PASI score, show the difference between the classic PASI and the Low PASI, evaluate the inter-observer agreement of both scores, and compare the two scores within investigators. METHODS: Cross-sectional study. Two investigators independently assessed the classic PASI and the Low PASI in 10 patients with mild-to-moderate plaque psoriasis. Differences in outcome between the two scores were calculated. Intra-class correlation coefficients (ICC) were used to determine the inter-observer agreement and to compare measurements of the two scores within both investigators. Prediction limits of 95% for the errors in measurements were provided. RESULTS: In both investigators, Low PASI was mean 1.71 and 1.76, whereas the classic PASI was mean 4.14 and 4.33. The inter-observer agreement (ICC) was excellent for both investigators in both scores (ICC classic PASI = 0.95 and Low PASI = 0.87). CONCLUSION: The Low PASI score allows more possible scores at lower levels of psoriasis extent (affected areas lower than 10% in a body region) compared to the classic PASI. This new score may lead to a more precise analysis of treatment responses and may have important clinical implications.

Systemic treatments in paediatric psoriasis: a systematic evidence-based update.

In 2008, a systematic review revealed that evidence-based data on efficacy and safety of treatments in paediatric psoriasis are scarce and with low level of evidence. In recent years, publications on this topic have increased exponentially. To present a systematic, evidence-based update on the efficacy and safety of systemic treatments in paediatric psoriasis and to provide treatment recommendations, an update of the previous review was performed. PubMed, EMBASE and the Cochrane Controlled Clinical Trial Register were searched between January 2007 and March 2014 for all available literature on efficacy and safety of all systemic treatments in paediatric psoriasis. The levels of evidence were determined on the Oxford Centre for Evidence-based Medicine Levels of Evidence. The newly retrieved evidence was combined with the evidence available in the former review. Fifty-two studies were included: 36 from the former review, plus 16 new articles. New evidence on induction therapy was mainly available on fumaric acid esters (FAEs), which are shown to be effective in a subgroup of patients. Long-term (96 weeks) safety and efficacy data on etanercept were found. Prospective studies are scarce. Most conclusions are formulated on studies with low level of evidence. Of the conventional systemic treatments, methotrexate still has the most evidence albeit in a low number of patients and with a low level of evidence. FAEs seem to be effective in a subgroup of patients, with gastro-intestinal complaints, flushes and temporary shifts in leucocyte counts and liver enzymes being the main side-effects. Etanercept has still accumulated most evidence of the available systematic treatments, with a large efficacy and reassuring safety profile in a 96-week follow-up.

Methotrexate in pediatric plaque-type psoriasis: Long-term daily clinical practice results from the Child-CAPTURE registry.

BACKGROUND: Evidence on effectiveness and safety of methotrexate (MTX) in pediatric psoriasis is scarce. OBJECTIVES: To study the effectiveness and safety of MTX in pediatric plaque-type psoriasis and its influence on quality of life (Qol) in daily clinical practice. METHODS: Subset analysis of prospectively collected data extracted from the Child-CAPTURE registry, a single center, longitudinal, long-term, observational daily practice cohort of pediatric psoriasis patients. A maximum dose between 0.14 and 0.63 mg/kg once weekly was prescribed in 25 children. Primary endpoints were percentages of patients with ≥ 75% improvement in the Psoriasis Area and Severity Index (PASI) at week 12 and 24. RESULTS: PASI75 was achieved in 4.3% and 33.3% of patients at week 12 and 24, whereas 40% and 28.6% reached PASI 75 at week 36 and 48. Median PASI and body surface area decreased from 10.0 (range 3.8-42.4) and 11.0 (range 3.5-72.0) at baseline to 4.3 (range 0-19.8) and 2.6 (range 0.0-39.6) at week 24, respectively. Physician Global Assessment improved significantly from 3.0 to 1.2 at week 24. A significant decrease in Children's Dermatology Life Quality Index from 9.0 to 3.8 at week 24 was found. Most reported adverse events were severe nausea (n = 5), infections requiring antibiotics (n = 5) and tiredness (n = 4). CONCLUSIONS: MTX shows a positive effect on PASI scores, improves Qol and has a reasonable safety profile.