"African" acral keratoderma: Further evidence for a single entity. A retrospective study of 42 patients.

BACKGROUND: Several phenotypes of non-inflammatory palmar and plantar keratoderma (PPK) have been described in patients of Sub-Saharan African descent. They include keratosis punctata of the palmar creases, marginal keratoderma, also known as acrokeratoelastoidosis or focal acral hyperkeratosis, knuckle pads, other forms of diffuse hyperkeratosis, the very rare "mosaic acral keratosis", and ainhum. A previous survey has shown that these various forms of PPK are particularly frequent in patients of Sub-Saharan African descent and that they commonly occur concurrently, suggesting that they could form part of a single entity called "African" Acral Keratoderma (AAK). AIM: To assess the validity of the concept of AAK and clarify its main characteristics. METHODS: A retrospective, descriptive, monocenter study was carried out on patients with AAK seen at our institution between 2009 and 2020. RESULTS: There were 42 patients (median age 38 years, range: 12-69 years), all of Sub-Saharan African descent. The male-female sex ratio was 0.3. Thirty-three (78%) had diffuse keratoderma, 25 (59%) had marginal keratoderma on their hands and/or feet, 20 (48%) had knuckle pads, 20 (48%) had keratosis punctata of the palmar creases, 3 had ainhum, and 2 had mosaic acral keratoderma. Mixed forms were seen in 76% of the patients (n = 32). Familial histories were reported by 17 patients (40%). Treatment was topical in over 90% of patients and systemic in 9 patients (21%). Ainhum was managed surgically. CONCLUSION: This retrospective study provides additional evidence for the concept of AAK. A genetic origin is suggested by the familial aggregation of cases.

Dystrophic epidermolysis bullosa pruriginosa: a new case series of a rare phenotype unveils skewed Th2 immunity.

BACKGROUND: Dystrophic epidermolysis bullosa pruriginosa (DEB-Pr) is a rare subtype of hereditary epidermolysis bullosa, with a poorly understood pathogenesis and no satisfactory treatment. OBJECTIVES: To assess the clinical and biological features, genetic basis and therapeutic management, to better characterize this rare genodermatosis. METHODS: We have conducted a retrospective study, reviewing the clinical presentation, genetic diagnosis, immunohistopathological findings and biological characteristics and management of patients with dystrophic epidermolysis bullosa pruriginosa. This study was conducted in the Department of Dermatology at Saint-Louis Hospital and the Department of Genetics at Necker Hospital (Paris, France). All patients with a diagnosis of DEB-Pr seen between 2010 and 2020 were included. RESULTS: Seven patients were included, the average age of 50.1 years [range 36-76]. Pruriginous-lichenified papules, plaques or nodules appeared at 27.6 years on average [range 7-66] on pretibial areas and forearms, associated with milia and toenails dystrophy. All patients received multiple treatments, but none could sustainably reduce pruritus. Immunohistopathological analysis of lesion skin revealed subepidermal blister with fibrosis, milia and mast cell infiltration. Serum TNFα, IL1ß and IL6 levels were elevated in 2/6 patients. Total serum IgE levels were increased in 7/7 patients, with no history of atopy. Immunophenotyping of circulating T-cells revealed an increased Th2 subset in 4/4 patients, with reduced Th1 and Th17 subpopulations. Genetic analysis of COL7A1 identified 7 distinct causative mutations, six of which were new. Intra-familial clinical variability was documented in 5/7 patients and was associated with the co-inheritance of a recessive COL7A1 mutation or an FLG2 mutation in 2 families. CONCLUSION: Our study confirms the stereotyped presentation of DEB-Pr with large intra-familial variability in disease expression. Mast cell infiltration, elevated IgE and increased Th2 subset without atopy strongly support a role of Th2-mediated immunity in DEB-Pr, and further argue for new targeted therapeutic options such as dupilumab.

The challenging management of a series of 43 infants with Netherton syndrome: unexpected complications and novel mutations.

BACKGROUND: Netherton syndrome (NS) is a rare disease caused by SPINK5 mutations, featuring variable skin and hair involvement and, in many cases, allergic manifestations with a risk of lethality, particularly in infants. The clinical management of NS is challenging. OBJECTIVES: To analyse the clinical manifestations of a cohort of infants with NS managed in a reference centre and to draw up recommendations for management. METHODS: We conducted a monocentric analysis of patients with NS. The inclusion criteria were management in our reference centre, a histologically or molecularly confirmed diagnosis of NS and available epidemiological, clinical and laboratory data. RESULTS: A total of 43 patients with NS were included. Hypernatraemia was reported in 23 cases (54%) and associated with a greater likelihood of enteral and/or parenteral nutritional support (P < 0.001). Moreover, hypernatraemia was more frequent in patients with skin manifestations at birth (P = 0.026) and in patients bearing the c.153delT mutation in SPINK5 exon 3 (P = 0.014). The need for enteral and/or parenteral nutritional support was associated with a history of hypernatraemic dehydration (P < 0.001). Several unexpected extracutaneous complications were recorded, and new mutations were reported. The death rate (9% overall) was higher among the subset of patients bearing the c.153delT deletion. CONCLUSIONS: Our data emphasize that neonatal NS is a severe and sometimes lethal multisystem disorder. Patients have a high risk of variable metabolic anomalies (i.e. lethal hypernatraemia) and therefore have major nutritional needs. Cases of NS associated with c.153delT are particularly severe. Unexpected clinical manifestations broadened the phenotypic spectrum of NS. We provide recommendations on the management of the life-threatening manifestations of NS in neonates based on our multidisciplinary experience.

Consensus reclassification of inherited epidermolysis bullosa and other disorders with skin fragility.

BACKGROUND: Several new genes and clinical subtypes have been identified since the publication in 2014 of the report of the last International Consensus Meeting on Epidermolysis Bullosa (EB). OBJECTIVES: We sought to reclassify disorders with skin fragility, with a focus on EB, based on new clinical and molecular data. METHODS: This was a consensus expert review. RESULTS: In this latest consensus report, we introduce the concept of genetic disorders with skin fragility, of which classical EB represents the prototype. Other disorders with skin fragility, where blisters are a minor part of the clinical picture or are not seen because skin cleavage is very superficial, are classified as separate categories. These include peeling skin disorders, erosive disorders, hyperkeratotic disorders, and connective tissue disorders with skin fragility. Because of the common manifestation of skin fragility, these 'EB-related' disorders should be considered under the EB umbrella in terms of medical and socioeconomic provision of care. CONCLUSIONS: The proposed classification scheme should be of value both to clinicians and researchers, emphasizing both clinical and genetic features of EB. What is already known about this topic? Epidermolysis bullosa (EB) is a group of genetic disorders with skin blistering. The last updated recommendations on diagnosis and classification were published in 2014. What does this study add? We introduce the concept of genetic disorders with skin fragility, of which classical EB represents the prototype. Clinical and genetic aspects, genotype-phenotype correlations, disease-modifying factors and natural history of EB are reviewed. Other disorders with skin fragility, e.g. peeling skin disorders, erosive disorders, hyperkeratotic disorders, and connective tissue disorders with skin fragility are classified as separate categories; these 'EB-related' disorders should be considered under the EB umbrella in terms of medical and socioeconomic provision of care. Linked Comment: Pope. Br J Dermatol 2020; 183:603.

Bone marrow transplant with post-transplant cyclophosphamide for recessive dystrophic epidermolysis bullosa expands the related donor pool and permits tolerance of nonhaematopoietic cellular grafts.

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is a severe systemic genodermatosis lacking therapies beyond supportive care for its extensive, life-limiting manifestations. OBJECTIVES: To report the safety and preliminary responses of 10 patients with RDEB to bone marrow transplant (BMT) with post-transplant cyclophosphamide (PTCy BMT) after reduced-intensity conditioning with infusions of immunomodulatory donor-derived mesenchymal stromal cells (median follow-up 16 months). METHODS: BMT toxicities, donor blood and skin engraftment, skin biopsies, photographic and dynamic assessments of RDEB disease activity were obtained at intervals from pre-BMT to 1 year post-BMT. RESULTS: Related donors varied from haploidentical (n = 6) to human leucocyte antigen (HLA)-matched (n = 3), with one HLA-matched unrelated donor. Transplant complications included graft failure (n = 3; two pursued a second PTCy BMT), veno-occlusive disease (n = 2), posterior reversible encephalopathy (n = 1) and chronic graft-versus-host disease (n = 1; this patient died). In the nine ultimately engrafted patients, median donor chimerism at 180 days after transplant was 100% in peripheral blood and 27% in skin. Skin biopsies showed stable (n = 7) to improved (n = 2) type VII collagen protein expression by immunofluorescence and gain of anchoring fibril components (n = 3) by transmission electron microscopy. Early signs of clinical response include trends toward reduced body surface area of blisters/erosions from a median of 49·5% to 27·5% at 100 days after BMT (P = 0·05), with parental measures indicating stable quality of life. CONCLUSIONS: PTCy BMT in RDEB provides a means of attaining immunotolerance for future donor-derived cellular grafts (ClinicalTrials.gov identifier NCT02582775). What's already known about this topic? Severe, generalized recessive dystrophic epidermolysis bullosa (RDEB) is marked by great morbidity and early death. No cure currently exists for RDEB. Bone marrow transplant (BMT) is the only described systemic therapy for RDEB. What does this study add? The first description of post-transplant cyclophosphamide (PTCy) BMT for RDEB. PTCy was well tolerated and provided excellent graft-versus-host disease prophylaxis, replacing long courses of calcineurin inhibitors in patients receiving human leucocyte antigen-matched sibling BMT. What is the translational message? The PTCy BMT platform permits identification of a suitable related donor for most patients and for subsequent adoptive transfer of donor nonhaematopoietic cells after establishment of immunological tolerance.

HLA-A*31:01 and different types of carbamazepine-induced severe cutaneous adverse reactions: an international study and meta-analysis.

HLA-A*31:01 was reported to be associated with carbamazepine (CBZ)-induced severe cutaneous adverse reactions (SCAR), including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We conducted an international study using consensus diagnosis criteria to enroll a total of 93 patients with CBZ-SCAR from Europe or Asia. We found that HLA-A*31:01 showed a significant association with CBZ-DRESS in Europeans (P<0.001; odds ratio (OR) (95% confidence interval (CI))=57.6 (11.0-340)), and the strong association was also found in Chinese (P<0.001; OR (95% CI)=23.0 (4.2-125)). However, HLA-A*31:01 had no association with CBZ-SJS/TEN in neither Chinese nor Europeans. By comparison, HLA-B*15:02 showed a strong association with CBZ-SJS/TEN in Chinese (P<0.001, OR (95% CI)=58.1 (17.6-192)). A meta-analysis of this and other published studies confirmed that in all populations, HLA-A*31:01 had an extremely strong association with CBZ-DRESS (P<0.001, a pooled OR (95% CI)=13.2 (8.4-20.8)), but a much weaker association with CBZ-SJS/TEN (P=0.01, OR (95% CI)=3.94 (1.4-11.5)). Our data revealed that HLA-A*31:01 is a specific predictor for CBZ-DRESS but not for CBZ-SJS/TEN. More studies are needed to investigate the genetic determinant of CBZ-SJS/TEN in Europeans. Considering the potential clinical utility, the cost-effectiveness of the combined HLA-A*31:01 and HLA-B*15:02 genetic test to prevent CBZ-SCAR in Chinese needs further investigation.

A missense mutation in the rod domain of keratin 14 associated with recessive epidermolysis bullosa simplex.

Epidermolysis bullosa simplex (EBS) is a group of epidermal blistering diseases almost invariably transmitted as a dominant trait, which has recently been shown to arise from mutations in keratins 14 and 5 (K14 and K5). We describe a family with recessive EBS in which the disease is tightly linked to the substitution of the highly conserved glutamic acid-144 to alanine in the first helical segment of the rod domain of keratin 14. In contrast, linkage with keratin 5 was excluded. The loss of an ionic interaction with keratin 5 is likely to affect K14-K5 heterodimer formation. Our data suggest that this mutation underlies EBS in our family, and that mutations in keratin genes may impair the mechanical integrity of basal keratinocytes in a recessive as well as dominant fashion.

A missense mutation in type VII collagen in two affected siblings with recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermolysis bullosa is a severe mutilating genodermatosis. Previous ultrastructural demonstrations of altered anchoring fibrils, and recent genetic linkage analyses have suggested that type VII collagen, the major component of anchoring fibrils, is a candidate gene. We have identified a homozygous methionine-to-lysine mutation in two affected siblings, while their unaffected mother and half-brother are heterozygous carriers. The mutation resides in a highly conserved region of the C-terminus of type VII collagen, strongly suggesting that it is the cause of the disease in this family.

A molecular defect in loricrin, the major component of the cornified cell envelope, underlies Vohwinkel's syndrome.

Terminal keratinocyte differentiation involves coordinated expression of several functionally interdependent genes, many of which have been mapped to the epidermal differentiation complex (EDC) on chromosome 1q21. We have identified linkage of Vohwinkel's syndrome in an extended pedigree to markers flanking the EDC region with a maximum multipoint lod score of 14.3. Sequencing of the loricrin gene revealed an insertion that shifts the translation frame of the C-terminal Gly- and Gln/Lys-rich domains, and is likely to impair cornification. Our findings provide the first evidence for a defect in an EDC gene in human disease, and disclose novel insights into perturbations of cornified cell envelope formation.

Mutations in SPINK5, encoding a serine protease inhibitor, cause Netherton syndrome.

We describe here eleven different mutations in SPINK5, encoding the serine protease inhibitor LEKTI, in 13 families with Netherton syndrome (NS, MIM256500). Most of these mutations predict premature termination codons. These results disclose a critical role of SPINK5 in epidermal barrier function and immunity, and suggest a new pathway for high serum IgE levels and atopic manifestations.

Gene polymorphism in Netherton and common atopic disease.

Atopic dermatitis (AD) and asthma are characterized by IgE-mediated atopic (allergic) responses to common proteins (allergens), many of which are proteinases. Loci influencing atopy have been localized to a number of chromosomal regions, including the chromosome 5q31 cytokine cluster. Netherton disease is a rare recessive skin disorder in which atopy is a universal accompaniment. The gene underlying Netherton disease (SPINK5) encodes a 15-domain serine proteinase inhibitor (LEKTI) which is expressed in epithelial and mucosal surfaces and in the thymus. We have identified six coding polymorphisms in SPINK5 (Table 1) and found that a Glu420-->Lys variant shows significant association with atopy and AD in two independent panels of families. Our results implicate a previously unrecognized pathway for the development of common allergic illnesses.

Mutations in ATP2A2, encoding a Ca2+ pump, cause Darier disease.

Darier disease (DD) is an autosomal-dominant skin disorder characterized by loss of adhesion between epidermal cells (acantholysis) and abnormal keratinization. Recently we constructed a 2.4-Mb, P1-derived artificial chromosome contig spanning the DD candidate region on chromosome 12q23-24.1. After screening several genes that mapped to this region, we identified mutations in the ATP2A2 gene, which encodes the sarco/endoplasmic reticulum Ca2(+)-ATPase type 2 isoform (SERCA2) and is highly expressed in keratinocytes. Thirteen mutations were identified, including frameshift deletions, in-frame deletions or insertions, splice-site mutations and non-conservative missense mutations in functional domains. Our results demonstrate that mutations in ATP2A2 cause DD and disclose a role for this pump in a Ca(2+)-signalling pathway regulating cell-to-cell adhesion and differentiation of the epidermis.

Netherton syndrome and its multifaceted defective protein LEKTI.

Netherton syndrome (NS, OMIM 256500) is a rare autosomal recessive disorder manifesting with congenital ichthyosis, a specific hair shaft abnormality named trichorrhexis invaginata, and atopic manifestations. Because of severe complications frequently occurring in the neonatal period, NS prognosis can be poor in infancy. NS is due to loss-of-function mutations in the SPINK5 gene and to the consequent lack of expression of its encoded protein LEKTI in the skin and all stratified epithelial tissues. Following the identification of the NS causative gene and protein, specific diagnostic tools have been developed, thus breaking up the challenge of distinguishing NS from other congenital ichthyoses with overlapping features, and from severe, early-onset forms of atopic dermatitis or psoriasis. Intensive efforts to extend the knowledge into the pathomechanisms of NS have also been made. However, NS management is still problematic due to the lack of specific treatment and unmet needs. This overview summarizes the current state of the art in NS research with an emphasis on the progress made toward disease-specific innovative therapy development.