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Patients with Nagashima-type palmoplantar keratoderma (NPPK) experience progressive, painful hyperkeratosis and fissuring of palms and soles that limits daily activities Due to the incomplete understanding of its pathogenesis, there are currently no effective treatments for NPPK. We report a 26-year-old woman with lifelong, worsening palmoplantar keratoderma, nail dystrophy, and concomitant atopic dermatitis refractory to topical treatments. Next-generation sequencing revealed compound heterozygous mutations in SERPINB7 (c.796C>T, p.Arg266Ter) and filaggrin (FLG, c.3321delA, p.Gly1109GlufsTer13), while her asymptomatic parents and brother carried only single heterozygous variants, underscoring the digenic pathogenesis in our patient. After 42 weeks of dupilumab treatment, palmoplantar keratosis and nail changes had almost completely resolved, and the eruption resembled mild chronic eczema. Dupilumab therefore appears to be a safe and effective option for digenic NPPK complicated by atopic dermatitis and warrants further investigation in larger cohorts.

SERPINA12 is a member of the serpin superfamily that has been extensively studied in metabolic and inflammatory disorders. In recent years, increasing evidence has highlighted its emerging role in skin physiology and dermatological diseases. SERPINA12 is expressed in multiple skin cell types, including keratinocytes and dermal fibroblasts, where it participates in the regulation of inflammation, cellular proliferation, differentiation, and tissue homeostasis. Dysregulation of SERPINA12 has been implicated in several skin disorders. In psoriasis, altered SERPINA12 expression is associated with chronic inflammation, immune dysregulation, and abnormal keratinocyte proliferation, suggesting a potential modulatory role in psoriatic pathogenesis. Furthermore, emerging studies suggest a possible involvement of SERPINA12 in palmoplantar keratoderma, where it may contribute to aberrant keratinization and epidermal barrier dysfunction. This review summarizes current knowledge on the expression patterns, biological functions, and molecular mechanisms of SERPINA12 in the skin, with a particular focus on adipocytes, psoriasis, and palmoplantar keratoderma. Understanding the role of SERPINA12 in cutaneous biology may provide new insights into disease pathogenesis and identify potential therapeutic targets for skin disorders.

Much of the original research on desmosomes and their biochemical components was through analysis of skin and mucous membranes. The identification of desmogleins 1 and 3, desmosomal adhesion glycoproteins, as targets in pemphigus, a fatal autoimmune blistering disease of the skin and mucous membranes, provided the first link between desmosomes, desmogleins, and human diseases. The clinical and histological similarities of staphylococcal scalded skin syndrome or bullous impetigo and pemphigus foliaceus led us to identify desmoglein 1 as the proteolytic target of staphylococcal exfoliative toxins. Genetic analysis of striate palmoplantar keratoderma and hypotrichosis identified their responsible genes as desmogleins 1 and 4, respectively. More recently, these fundamental findings in cutaneous biology were extended beyond the skin. Desmoglein 2, which is expressed earliest among the four isoforms of desmoglein in development and found in all desmosome-bearing epithelial cells, was found to be mutated in arrythmogenic right ventricular cardiomyopathy and has also been identified as a receptor for a subset of adenoviruses that cause respiratory and urinary tract infections. The story of desmoglein research illuminates how dermatological research, originally focused on one skin disease, pemphigus, has contributed to understanding the biology and pathophysiology of many seemingly unrelated tissues and diseases.

Acrokeratoelastoidosis (AKE) is a rare autosomal dominant hereditary skin disease characterized by small, round-oval, flat-topped keratotic papules on the palms, soles and dorsal aspect of hands or feet. The causative gene for AKE remains unidentified. This study aims to identify the causative gene of AKE and explore the underlying biological mechanisms. A large, three-generation Chinese family exhibiting classic AKE symptoms was identified. A genome-wide linkage analysis and whole-exome sequencing were employed to determine the causative gene. shRNA knockdown in human skin fibroblasts and CRISPR/Cas9 knockout in HEK293T cells were utilized to assess gene functions in the progression of elastic fiber biosynthesis. The linkage analysis identified a susceptibility region between rs7296765 to rs10784618 on chromosome 12. Whole-exome sequencing confirmed a splicing mutation of 1101 + 1  G  >  A in the CCDC91 gene, resulting in exon 11 skipping and a subsequent 59-amino-acid-residue loss (residues L309-Q367del). Further functional analysis revealed distended Golgi cisternae, cytoplasmic vesicle accumulation, and lysosome presence. Immnunostaining of si-CCDC91-HSF cells demonstrated tropoelastin accumulation in the Golgi and abnormal extracellular aggregates. There are no significant changes in Fibrillin-1 microfibril assembly and lysyl oxidase activity. The findings strongly suggest that the protein product of the CCDC91 gene plays a crucial role in elastin transport. This discovery enhances our understanding of CCDC91 ’s function and broadens the known pathogenic mechanisms of AKE.

Carvajal syndrome, a rare autosomal recessive disorder caused by mutations in the gene, is characterised by woolly hair, palmoplantar keratoderma, and left ventricular dilated cardiomyopathy. Although less frequently reported, noncompaction cardiomyopathy can co-occur, further complicating the clinical picture. Early diagnosis and management are crucial due to the high risk of progressive heart failure and sudden cardiac death in affected individuals. A 13-year-old male with autism presented with a 1.5-month history of persistent cough and worsening clinical symptoms, including hepatomegaly and signs of heart failure. Physical examination revealed woolly hair, patchy alopecia, nail anomalies, and ectodermal dysplasia. Echocardiography demonstrated left ventricular dilated cardiomyopathy, noncompaction, and a severely reduced ejection fraction of 23%. Initial management in the paediatric intensive care unit included inotropic support, diuretics, and beta-blockers. Genetic analysis confirmed a homozygous c.7912G > T nonsense variant in the gene, establishing the diagnosis of Carvajal syndrome. The patient was referred to an advanced cardiac centre. Carvajal syndrome involves multisystem manifestations, with prominent dermatologic and cardiovascular features. Unlike Naxos disease, which primarily affects the right ventricle, Carvajal syndrome predominantly involves the left ventricle, as observed in this case. Notably, left ventricular noncompaction was a striking feature in our patient, further exacerbating cardiac dysfunction and complicating the clinical course. Although noncompaction cardiomyopathy is less frequently reported in Carvajal syndrome, its pronounced presence in this case underscores the phenotypic variability and severity of myocardial involvement. Intensive care management with a multidisciplinary approach was essential in stabilising this patient. Genetic testing confirmed the diagnosis and highlighted the importance of molecular diagnostics in differentiating cardiocutaneous syndromes.

Tylosis (hyperkeratosis palmaris et plantaris) is characterised by focal thickening of the skin of the hands and feet and is associated with a very high lifetime risk of developing squamous cell carcinoma of the oesophagus. This risk has been calculated to be 95 % at the age of 65 in one large family, however the frequency of the disorder in the general population is not known and is likely to be less than one in 1,000,000. Oesophageal lesions appear as small (2–5 mm), white, polyploid lesions dotted throughout the oesophagus and oral leukokeratosis has also been described. Although symptoms of oesophageal cancer can include dysphagia, odynophagia, anorexia and weight loss, there may be an absence of symptoms in early disease, highlighting the importance of endoscopic surveillance in these patients. Oesophageal cancer associated with tylosis usually presents in middle to late life (from mid-fifties onwards) and shows no earlier development than the sporadic form of the disease. Tylosis with oesophageal cancer is inherited as an autosomal dominant trait with complete penetrance of the cutaneous features, usually by 7 to 8 years of age but can present as late as puberty. Mutations in RHBDF2 located on 17q25.1 have recently been found to be causative. A diagnosis of tylosis with oesophageal cancer is made on the basis of a positive family history, characteristic clinical features, including cutaneous and oesophageal lesions, and genetic analysis for mutations in RHBDF2 . The key management goal is surveillance for early detection and treatment of oesophageal dysplasia. Surveillance includes annual gastroscopy with biopsy of any suspicious lesion together with quadratic biopsies from the upper, middle and lower oesophagus. This is coupled with dietary and lifestyle modification advice and symptom education. Symptomatic management of the palmoplantar keratoderma includes regular application of emollients, specialist footwear and early treatment of fissures and super-added infection, particularly tinea pedis. More specific treatment for the thick skin is available in the form of oral retinoids, which are very effective but commonly produce side effects, including nasal excoriation and bleeding, hypercholesterolaemia, and abnormal liver function tests. Genetic counselling can be offered to patients and family members once a family history has been established. The prognosis of tylosis with oesophageal cancer is difficult to determine due to the limited number of affected individuals. In the last 40 years of surveillance, five out of six cases of squamous oesophageal cancer in the Liverpool family were detected endoscopically and were surgically removed. Four of five patients had stage 1 disease at presentation and remain alive and well more than 8 years later. This suggests that the presence of a screening program improves prognosis for these patients.

Palmoplantar keratoderma (PPK) are debilitating lesions that arise in individuals with pachyonychia congenita (PC) and feature upregulation of danger-associated molecular patterns and skin barrier regulators. The defining features of PC-associated PPK are reproduced in mice null for keratin 16 (Krt16), which is commonly mutated in PC patients. Here, we have shown that PPK onset is preceded by oxidative stress in footpad skin of Krt16-/- mice and correlates with an inability of keratinocytes to sustain nuclear factor erythroid-derived 2 related factor 2-dependent (NRF2-dependent) synthesis of the cellular antioxidant glutathione (GSH). Additionally, examination of plantar skin biopsies from individuals with PC confirmed the presence of high levels of hypophosphorylated NRF2 in lesional tissue. In Krt16-/- mice, genetic ablation of Nrf2 worsened spontaneous skin lesions and accelerated PPK development in footpad skin. Hypoactivity of NRF2 in Krt16-/- footpad skin correlated with decreased levels or activity of upstream NRF2 activators, including PKCδ, receptor for activated C kinase 1 (RACK1), and p21. Topical application of the NRF2 activator sulforaphane to the footpad of Krt16-/- mice prevented the development of PPK and normalized redox balance via regeneration of GSH from existing cellular pools. Together, these findings point to oxidative stress and dysfunctional NRF2 as contributors to PPK pathogenesis, identify K16 as a regulator of NRF2 activation, and suggest that pharmacological activation of NRF2 should be further explored for PC treatment.

Assembly of protein complexes is facilitated by assembly chaperones. Alpha and gamma adaptin-binding protein (AAGAB) is a chaperone governing the assembly of the heterotetrameric adaptor complexes 1 and 2 (AP1 and AP2) involved in clathrin-mediated membrane trafficking. Here, we found that before AP1/2 binding, AAGAB exists as a homodimer. AAGAB dimerization is mediated by its C-terminal domain (CTD), which is critical for AAGAB stability and is missing in mutant proteins found in patients with the skin disease punctate palmoplantar keratoderma type 1 (PPKP1). We solved the crystal structure of the dimerization-mediating CTD, revealing an antiparallel dimer of bent helices. Interestingly, AAGAB uses the same CTD to recognize and stabilize the γ subunit in the AP1 complex and the α subunit in the AP2 complex, forming binary complexes containing only one copy of AAGAB. These findings demonstrate a dual role of CTD in stabilizing resting AAGAB and binding to substrates, providing a molecular explanation for disease-causing AAGAB mutations. The oligomerization state transition mechanism may also underlie the functions of other assembly chaperones.

Nagashima-type palmoplantar keratosis (NPPK) is the most prevalent palmoplantar keratoderma (PPK) in East Asia. Homozygous or compound heterozygous loss-of-function mutations in serpin peptidase inhibitor, clade B (ovalbumin), and member 70 (SERPINB7), which encodes members of the serine protease inhibitor superfamily, have been identified as the cause of NPPK. Clinical manifestations of NPPK include well-demarcated erythema, mild to moderate hyperkeratosis on the whole palm, and sole with transgrediens, extending to the dorsal surfaces of the hands and feet, inner wrists, ankles, and the Achilles tendon areas. In this study, we perform a review of relevant clinical cases aimed at elucidating the clinical characteristics, genetic characterization, differential diagnoses, and clinical management of NPPK. A better understanding of the clinical characteristics and pathogenic gene characterization of NPPK will enhance the diagnosis of NPPK, identify related diseases, and inform on the precise therapy and prognosis. Moreover, it will promote the awareness of NPPK in non-Asian regions.

Buschke–Fischer–Brauer keratoderma is a rare autosomal dominant disorder presenting as hyperkeratotic lesions on the palms and soles. Diagnosis requires clinical and histopathological evaluation. Management is symptomatic with keratolytics like salicylic acid and urea. Early recognition and ongoing care improve the quality of life for patients with this chronic condition.