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Autosomal recessive congenital ichthyosis ( ARCI) caused by mutations in CYP4F22 is very rare. CyP4F22, a protein of the cytochrome-P450 family 4, encodes an epidermal ω-hydroxylase decisive in the formation of acylceramides, which is hypothesized to be crucial for skin-barrier function. We report a girl with consanguineous parents presenting as collodion baby with contractures of the great joints and palmoplantar hyperlinearity. In the course of the disease she developed fine scaling of the skin with erythroderma, the latter disappearing until the age of 6 months. Her sister showed a generalized fine-scaling phenotype, and, interestingly, was born without a collodion membrane. The analysis of all known candidate genes for ARCI in parallel with a next-generation sequencing approach using a newly designed dermatogenetics gene panel revealed a previously unknown homozygous splice-site mutation c.549+5G>C in CYP4F22 in both girls, confirming the diagnosis of ARCI. Ultrastructural analysis by transmission electron microscopy in both patients showed epidermal hyperplasia, orthohyperkeratosis with persistence of corneodesmosomes into the outer stratum corneum layers, fragmented and disorganized lamellar lipid bilayers, which could be ascribed to inhomogeneous lamellar body secretion, as well as lamellar body and lipid entombment in the corneocytes. These findings correlated with increased transepidermal water loss on the functional level. For the first time, we report a collodion baby phenotype and epidermal barrier impairment in CyP4F22-deficient epidermis at both the ultrastructural and functional level, and corroborate the importance of CyP4F22 for epidermal maturation and barrier function. [ABSTRACT FROM AUTHOR]

Pachyonychia congenita (PC), a rare autosomal-dominant keratin disorder caused by mutations in keratin genes KRT6A/B, KRT16 or KRT17, is characterized by painful plantar keratoderma and hypertrophic nail dystrophy. Loss-of-function mutations in the filaggrin ( FLG) gene underlie the most prevalent skin disorder of cornification, ichthyosis vulgaris (IV), which presents with generalized scaling and is also associated with atopic dermatitis. Recently, FLG mutations have been reported to increase phenotype severity of X-linked ichthyosis and alopecia areata. We report a parent–child trio in which the mother and the son have PC and the father has IV. Both the mother and the son are carriers for the KRT16 mutation p.Leu132Pro. The son, who is much more severely affected than his mother, in addition carries the heterozygous FLG mutation p.R2447X, which was inherited from the father. This observation suggests that coinheritance of mutations in KRT16 and FLG may aggravate the PC phenotype and that FLG could serve as a genetic modifier in PC. [ABSTRACT FROM AUTHOR]

The article discusses research on the risk of psoriasis in subjects with childhood asthma. It references a study by A. Egeberg et al published within the issue. Topics covered include the underlying pathophysiology in psoriasis, the major advantages of the study, and the bidirectional relationship between psoriasis and asthma.

Linked Article: Valentin et al. Br J Dermatol 2021; 184:1123–1131. [ABSTRACT FROM AUTHOR]

Summary: These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016, and a consensus on the discussions. These guidelines summarize evidence and expert‐based recommendations and intend to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part two, covering the management of complications and the particularities of some forms of congenital ichthyosis. What's already known about this topic? Various symptomatic treatment options exist for congenital ichthyoses, but there are no European guidelines. What does this study add? These European guidelines for the management of congenital ichthyosis may help to improve outcomes and quality of life for patients. Linked Comment:Akiyama. Br J Dermatol 2019; 180:449–450. Plain language summary available online [ABSTRACT FROM AUTHOR]

Summary: These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016 and a consensus on the discussions. They summarize evidence and expert‐based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling. Linked Comment:  Levy. Br J Dermatol 2019; 180:253. [ABSTRACT FROM AUTHOR]

Autosomal recessive exfoliative ichthyosis ( AREI) results from mutations in CSTA, encoding cysteine protease inhibitor A (cystatin A). We present a 25-year-old man from Iran with consanguineous parents, who presented with congenital erythroderma, hyperhidrosis and diffuse hyperkeratosis with coarse palmoplantar peeling of the skin, aggravated by exposure to water and by occlusion. Candidate gene analysis revealed a previously unknown homozygous loss-of-function mutation c.172C>T (p.Arg58Ter) in CSTA, and immunostaining showed absence of epidermal cystatin A, confirming the diagnosis of AREI. Ultrastructural analysis by transmission electron microscopy showed normal degradation of corneodesmosomes, mild intercellular oedema in the spinous layer but not in the basal layer, normal-appearing desmosomes, and prominent keratin filaments within basal keratinocytes. Thickness of cornified envelopes was reduced, lamellar lipid bilayers were disturbed, lamellar body secretion occurred prematurely and processing of secreted lamellar body contents was delayed. These barrier abnormalities were reminiscent of (albeit less severe than in) Netherton syndrome, which results from a deficiency of the serine protease inhibitor LEKTI. This work describes ultrastructural findings with evidence of epidermal barrier abnormalities in AREI. [ABSTRACT FROM AUTHOR]

Background Ichthyosis vulgaris (IV) is a genetic disorder with a prevalence of 1 : 250–1000 caused by filaggrin ( FLG) mutations, which also predispose to atopic diseases. Objectives To study the genotype/phenotype relationship in IV and to analyse whether the suggested skin barrier defect is associated with differences of epidermal dendritic cells. Patients/methods We evaluated a cohort of 26 German patients with IV, established an IV severity score and analysed epidermal ultrastructure, histology, filaggrin and CD1a antigens. Mutations were screened by restriction enzyme analysis. Particular sequencing techniques allowed the complete FLG analysis to reveal novel mutations. Results The combined null allele frequency of R501X and 2282del4 was 67·3%. Patients also showed the mutations S3247X and R2447X as well as five novel FLG mutations: 424del17 and 621del4 (profilaggrin S100 domain), 2974delGA (repeat 2), R3766X (repeat 101) and E4265X (repeat 102). Their combined allele frequency in controls was < 0·7%. No mutation was found in one IV patient, all in all ∼27% were heterozygous, and the majority (∼69%) showed two null alleles. The IV severity score and ultrastructure showed a significant correlation with genotypes. Interestingly, CD1a cell counts showed a significant difference between nonatopic and atopic IV patients both with eczema and without eczema. Conclusions We confirm that the mutations R501X and 2282del4 represent the most frequent genetic cause in German IV patients. The novel mutations are probably population and family specific. The observed differences of CD1a cells support the hypothesis that there is a barrier defect that predisposes to atopic manifestations, possibly independent of atopic eczema. [ABSTRACT FROM AUTHOR]

Linked Article: Mazereeuw‐Hautier et al. Br J Dermatol 2019; 180:484–495 [ABSTRACT FROM AUTHOR]

Summary: Ichthyosis is the term used to describe continual and widespread scaling of the skin. There are several genetic types which are present from birth and persist life‐long – the "congenital ichthyoses". There is no agreed treatment ‐ different doctors use different approaches, so this group of experts from all over Europe worked together to develop guidelines. They reviewed the medical literature and met to discuss the evidence and to make recommendations. A separate paper (Part 1) covered treatments for the skin condition itself. This paper, Part 2, provides guidelines for managing complications of the congenital ichthyoses. Itch, pain and infections are common, particularly fungal infection, and cancers sometimes occur. Tight skin often prevents eyelids from shutting properly so the eye surface must be protected with lubricant; eyelid massage may help and retinoid medicine may soften tight skin but can dry the eyes further. Surgical options include injecting filler or grafting extra skin to the eyelid: if the patient's own ichthyotic skin is used the problem eventually recurs and mucous membrane from inside the mouth is a promising alternative. Hearing is commonly affected: blockage of ears by a build‐up of skin may be prevented by regular oil drops but syringing or suction may be necessary. In children, growth may be affected and vitamin D supplements are usually recommended. There are special considerations for newborn babies and those with complex ichthyotic disorders such as Netherton Syndrome, epidermolytic ichthyosis and Ichthyosis Prematurity Syndrome. These treatment guidelines should help to improve outcomes and quality of life for patients with congenital ichthyoses. Linked Article: Mazereeuw‐Hautier et al. Br J Dermatol 2019; 180:484–495 [ABSTRACT FROM AUTHOR]