Editor's Choice: rare skin diseases themed issue
Authors: John Ingram
Journal: British Journal of Dermatology (2020)

This issue of the BJD aims to shine a light on rare skin diseases, which may sometimes be overlooked due to commercial or journal impact imperatives. By definition research into these conditions often requires multinational collaboration, and the European Reference Network (ERN)-Skin is an excellent example. The ERN-Skin is a European Union initiative to optimize the management of patients with rare skin diseases, and it supported this expert consensus review of mosaic skin disorders. The review includes cutaneous phenotype, extracutaneous associated features and genotype, and proposes a new classification system based on inheritance potential. It offers practical tips on correct sample collection and genetic investigation and reviews trials of targeted therapies in mosaic skin disorders, such as rapamycin for vascular malformations. In addition, it offers guidelines for a practical clinical approach to the patient with suspected mosaicism. Kinsler VA, Boccara O, Fraitag S et al. Mosaic abnormalities of the skin: review and guidelines from the European Reference Network for rare skin diseases. Br J Dermatol 2020; 182:552–563. This evidence-based guideline, supported by Dystrophic Epidermolysis Bullosa Research Association (DEBRA) International, is designed to improve foot care for people and their families and carers, living with epidermolysis bullosa (EB). A survey of the EB community indicated the following priorities that are covered by the guideline: blistering and wound management, optimal footwear and hosiery for EB, management of dystrophic nails, hyperkeratosis (callus), maintaining mobility, and fusion of toes (pseudosyndactyly). The guideline methodology involved a systematic review to inform four panel meetings attended by clinical experts, methodologists, patients and carers. Khan MT, O'Sullivan M, Faitli B et al. Foot care in epidermolysis bullosa: evidence-based guideline. Br J Dermatol 2020; 182:593–604. The rarity of epidermal necrolysis (Stevens–Johnson syndrome and toxic epidermal necrolysis) poses a challenge for epidemiologists. A capture–recapture analysis using four French national databases estimated, during a 14-year period from 2003 to 2016, an occurrence of 5686 cases with an annual incidence of 6·5 [95% confidence interval (CI) 4·1–8·9] cases per million French inhabitants. This is higher than the 1–5 cases per million inhabitants previously estimated. The overall annual mortality rate was 0·9 (95% CI 0·1–1·8) cases per million inhabitants. Incidence and mortality were greatest in those older than 65 years, at 13·7 (95% CI 5·4–22·0) and 2·8 (95% CI 0·9–6·6) per million older inhabitants, respectively. The data will be valuable when planning healthcare provision for this resource-intensive condition, in particular guiding decisions about the need for and number of national specialized care units. Chaby G, Maldini C, Haddad C et al. Incidence of and mortality from epidermal necrolysis (Stevens–Johnson syndrome/toxic epidermal necrolysis) in France during 2003–16: a four-source capture–recapture estimate. Br J Dermatol 2020; 182:618–624. Recessive forms of congenital ichthyosis are rare but often difficult to diagnose and, so far, 13 genes have been implicated. An English cohort of 146 individuals was recruited for deep phenotyping and DNA mutation screening using a next-generation-sequencing ichthyosis gene panel and Sanger sequencing. Pathogenic mutations were found in 83% of cases, the commonest being mutations of TGM1 (29% of all cases). A new clinical sign, an anteriorly overfolded ear at birth, was noted in six of 14 patients (43%) with ALOX12B mutations. The need for intensive care stay (P = 0·004), and hand deformities (P < 0·001), were associated with ABCA12 mutations. Self-improving collodion ichthyosis occurred in 8% of cases, without a predictable link to genotype. Simpson JK, Martinez-Quiepo M, Onoufriadis A et al. Genotype–phenotype correlation in a large English cohort of patients with autosomal recessive ichthyosis. Br J Dermatol 2020; 182:729–737.