Pigment Cell & Melanoma Research

I.Cutaneous skin melanomas with wild-type BRAF alleles ("BRAF-WT melanomas") remain relatively difficult to treat, even though they typically possess driver mutations in a RAS gene or NF1. For example, these tumors respond relatively poorly to combinations of MEK and BRAF inhibitors, and their response to ICIs is muted compared to the response of BRAF-mutant melanomas. ERBB2 and ERBB4, which encode receptor tyrosine kinase genes, are necessary and sufficient for the proliferation of multiple BRAF-WT melanoma cell lines. Consequently, we have postulated that ERBB4-ERBB2 heterodimerization drives BRAF-WT melanomas. This mechanism is consistent with the observation that elevated ERBB4 transcription or ERBB4 mutations are found in a significant fraction of BRAF-WT melanoma tumor samples. Moreover, a subset of ERBB4 mutations found in BRAF-WT melanoma samples increases proliferation in a BRAF-WT melanoma cell line. Because the elevated ERBB4 transcription observed in BRAF- WT melanomas is typically insufficient to cause ligand-independent ERBB4 signaling, we have postulated that ligands for ERBB family receptors drive the elevated ERBB4-ERBB2 heterodimerization responsible for the proliferation of BRAF-WT melanoma cell lines. We have explored this hypothesis by analyzing data found in the Broad Institutes Cancer Cell Line Encyclopedia. These data suggest that some EGF family hormones are required for the proliferation of BRAF-WT melanoma cell lines. Likewise, the G11/Gq pathway, which can stimulate cleavage and maturation of EGF family hormones, is also required for the proliferation of BRAF-WT melanoma cell lines. Thus, these data suggest additional therapeutic targets in BRAF-WT melanomas. Moreover, because many uveal (ocular) melanomas possess elevated G11/Gq signaling, these data suggest that ligand stimulation of ERBB receptor signaling may contribute to uveal melanomagenesis or progression.

PurposeThe short lifespan of primary normal choroidal melanocytes (NCMs) in vitro represents a major barrier to mechanistic, functional, and translational studies of choroid biology and uveal melanoma (UM). This study aimed to establish and characterize immortalized human NCM lines that retain melanocytic function, maintain a non-cancerous profile, and are amenable to gene editing. MethodsNCMs from four donors were immortalized by lentiviral transduction of Cyclin-dependent kinase 4 (CDK4R24C), Cyclin D1, and human Telomerase reverse transcriptase (hTERT), establishing NCM-K4DT lines. Their morphology, melanocytic marker expression, proliferation and functional properties (melanin synthesis, tyrosinase activity) were evaluated. Genomic stability was assessed by targeted mutation profiling, karyotyping, and copy number variation analysis. The tumorigenicity was tested in immunodeficient mice. Plasmid-based CRISPR/Cas9 editing was performed to determine their suitability for gene editing. ResultsNCM-K4DT lines retained dendritic-shaped morphology, pigmentation, and expression of PMEL, TYRP1, Melan-A, and SOX10. Cells exhibited enhanced proliferative capacity with preserved cell cycle regulation. Melanin production and tyrosinase activity were comparable to primary NCMs. Genomic profiling confirmed the absence of UM-associated driver mutations and chromosomal abnormalities. In vivo growth assays demonstrated no tumorigenic potential. Notably, NCM-K4DT cells were efficiently edited by CRISPR/Cas9. ConclusionsNCM-K4DT lines represent stable, non-cancerous, and genetically tractable models for studying choroidal melanocyte biology, modeling UM-associated mechanisms, and advancing therapeutic development in ocular research.

PurposeFuchs endothelial corneal dystrophy (FECD) is a common corneal disease and a leading indication for endothelial keratoplasty (EK). Although CTG18.1 repeat expansion is a major genetic risk factor, the contribution of polygenic background to disease progression remains unclear. We evaluated whether combining CTG18.1 expansion status with a FECD-specific polygenic risk score (PRS) enables genomic prediction of progression to EK. MethodsWe retrospectively analysed 589 individuals with FECD from two European centers, with replication in an independent cohort of 185 individuals. Association of CTG18.1 expansion ([&ge;]50 repeats) and PRS with time to EK were evaluated using Cox models adjusted for sex and ancestry. ResultsExpansion-positive status was associated with earlier EK (HR 2.30; 95% CI 1.62- 3.26; P<.001). Addition of PRS improved prediction (C-index 0.614 vs 0.602; P=.014). Each 1-SD increase in PRS was associated with earlier EK (HR 1.16; 95% CI 1.03-1.30; P=.015), with replication in the validation cohort (HR 1.42; 95% CI 1.15-1.75; P=.001). ConclusionIntegration of monogenic and polygenic risk enables genomic prediction of FECD progression, supporting clinical genomic risk stratification to inform individualized monitoring and timing of intervention.

Background: Human papillomaviruses (HPVs) pose a severe threat to global public health by driving nonmelanoma skin cancer (NMSC) and cervical cancer, with NMSC being one of the most common cancers worldwide. Epidermodysplasia verruciformis (EV) is an inborn error of immunity characterized by an increased susceptibility to persistent infection of cutaneous HPV and a high risk of NMSC. The genetic basis remains unknown in many patients with EV. Methods: We collected four unrelated pedigrees with EV. Genetic analysis identified five variants in JAK1 encoding the Janus kinase 1. Ex vivo models and patient-derived tissue were employed to evaluate the functional effects of JAK1 variants and delineate the pathogenic mechanisms. Results: We identified different variants in JAK1 in four pedigrees with dominant EV. Genetic analysis revealed five novel variants in JAK1, three of which resulted in nonsense-mediated mRNA decay (NMD). Functional assays identified a decreased phosphorylation of the signal transducers and activators of transcription (STATs), impaired interferon responses, and defective T cell activation. Immune dysregulation in patients, characterized by a reduced CD4/CD8 T cell ratio, decreased CD8 naive T cell proportion, and accumulated memory T cells, implies impaired antiviral immunity against HPV. Conclusions: Our findings confirm that JAK1 loss-of-function (LOF) variants underlie susceptibility to cutaneous HPV infection. [Funded by the National Natural Science Foundation of China (81788101, 81230015, 82394420, and 82394423), the National Key Research and Development Program of China (2022YFC2703900), the CAMS Innovation Fund for Medical Sciences (2021-I2M-1-018), and the Regione Lombardia, Italy (Innovative Research Project 1137-2010)].

Leber hereditary optic neuropathy (LHON) is primarily caused by pathogenic mitochondrial DNA (mtDNA) variants, most commonly the m.11778G>A variant in the MT-ND4 gene. The presence of this variant alone is insufficient to trigger disease symptoms, of which vision loss is the hallmark. Given the incomplete penetrance and inter-population variability in modifying factors, this study aimed to investigate two previously proposed genetic risk factors for LHON in the Polish population. Using quantitative PCR, we measured the mtDNA copy number in peripheral blood of affected and unaffected carriers of the m.11778G>A variant. In addition, we assessed the frequency of the PRICKLE3 c.157C>T variant in symptomatic, asymptomatic and control individuals using PCR-RFLP. Our results indicate that neither mtDNA copy number nor the presence of the PRICKLE3 variant is associated with LHON symptom manifestation in the Polish cohort under conditions tested, in contrast to previously reported associations in other populations. These findings suggest that the incomplete penetrance of LHON in the Polish population may involve other modifying factors, such as yet unidentified nuclear DNA variants. Research highlightsO_LIMitochondrial DNA (mtDNA) copy number and the presence of the c.157C>T variant in the PRICKLE3 gene do not influence the manifestation of Leber hereditary optic neuropathy (LHON) symptoms in the Polish population. C_LIO_LIThe results support a geographic dependence of genetic risk factors affecting the penetrance of LHON-associated mtDNA variants. C_LI

Plumage colour in domestic geese is an important economic trait and a selection target since the early days of domestication. In European domestic geese of greylag goose (Anser anser) origin, white plumage colour is known to be caused by two independent loci, one causing white spotting and one causing sex-linked dilution, together producing white plumage. Strong candidate mutations have been identified upstream of the EDNRB2/LOC106047519 gene (endothelin receptor B-like) and within the sex-linked MLANA gene (melan-A). To confirm these candidate mutations, we genotyped differently coloured European domestic goose breeds, wild greylag geese, Chinese domestic geese (derived from swan goose A. cygnoid) and European and Chinese domestic geese crossbreeds. One base pair deletion in the MLANA gene (NW_013185876.1: g.950,868 C > -) was confirmed to cause sex-linked dilution, and thus autosexing (almost white gander and goose diluted grey). However, mutation upstream of EDNRB2/LOC106047519 (NW_013185915.1: g. 775,151 G > T) was not the causative mutation for saddleback pattern but strongly linked to it in European domestic geese. We sequenced the EDNRB2 gene and coding sequence of a neighbouring VAMP7 gene (vesicle-associated membrane protein 7) but found no genetic variaion linked to colour. Additionally, we sequenced the coding sequence of TYRP1 (tyrosinase related protein 1), a candidate gene for buff colouration, but no variation linked to colour was found. Further, we genotyped a 14-bp insertion in exon 3 of the EDNRB2 gene, known to be causative of the white phenotype in the Chinese domestic goose, and identified it in one European domestic goose individual.

Heterozygous FOXL2 (non-)coding sequence and structural variants (SVs) lead to blepharophimosis, ptosis and epicanthus inversus syndrome (BPES), a rare, autosomal dominant developmental disorder characterized by a completely penetrant eyelid malformation and incompletely penetrant primary ovarian insufficiency (POI). We collected variants from our in-house database, generated via clinical genetic testing and downstream research testing in the Center for Medical Genetics Ghent, Belgium (2001-2024), and via literature and other resources in the same period. All retrieved variants were categorized using ACMG/AMP classifications to increase the knowledge of pathogenicity. We collected 413 unique genetic defects of the FOXL2 region, including 76 novel variants, in 864 index patients. Of these, 87% of patients were identified with a coding FOXL2 sequence variant. The polyalanine tract is a known mutational hotspot of FOXL2, illustrated here by the high percentage of pathogenic polyalanine expansions (24%). Furthermore, the molecular spectrum in typical BPES index patients is characterized by 8% coding deletions and 3% deletions located up- and downstream of FOXL2. The remaining 2% carry translocations along with chromosomal rearrangements of 3q23. This uniform and structured reclassification, incorporating the largest dataset of variants implicated in FOXL2-associated disease so far, will improve both the diagnosis as well as genetic counselling for individuals with BPES.

ObjectiveTo identify risk loci for Fuchs endothelial corneal dystrophy (FECD) and improve a genetic risk prediction model. DesignGenome-wide association study (GWAS), polygenic risk score (PRS) construction, and TCF4 CTG18.1 short tandem repeat (STR) length inference. ParticipantsThe study included 7,316 Europeans (EUR) with FECD or related corneal dystrophy phenotypes and 1,588,467 controls from the UK Biobank, All of Us, FinnGen, and the Million Veteran Program. Two independent EUR FECD cohorts were used for PRS validation (1,851/2,679 cases/controls and 124/257 cases/controls). African (AFR) ancestry analyses included 455 cases and 121,154 controls to build PRS. A subset of All of Us participants was used for joint PRS and STR modelling. MethodsGWAS meta-analyses were performed using FECD diagnoses or corneal dystrophy proxies where necessary, with validity assessed via genetic correlation. Risk loci were identified, and ancestry-specific PRSs were constructed using SBayesRC. PRS performance was evaluated across ancestries with and without TCF4 STR data. Main OutcomeWe identified novel loci for corneal dystrophy and constructed PRS-based and STR-based prediction models. ResultsThe GWAS meta-analysis identified 24 risk loci associated with corneal dystrophy, including 12 novel loci, doubling previous FECD studies. The optimised PRS outperformed existing models in two independent FECD validation cohorts (AUC = 0.83, 95% CI: 0.82-0.84; DeLongs P = 7.04 x 10-19), with individuals in the top PRS decile showing 14-fold and 19-fold increased risk in the two validation sets, respectively In All of Us, STR expansion (>40 repeats) was the key predictor of FECD risk, yielding excellent discrimination (AUC = 0.89; OR = 54) with minimal improvement from PRS. Consistent with this, STR expansion remained the primary driver of risk across ancestries, while PRS provided modest independent value for broader corneal dystrophy phenotypes in EUR and admixed American populations. Among participants without large STR expansion, overall predictive performance was modest; PRS was the only significant genetic contributor (OR = 1.37) for broader corneal dystrophy in Europeans, whereas analyses in FECD non-expansion carriers were underpowered. ConclusionsThese findings refine the genetic architecture of FECD, enhance risk prediction, and support a tiered strategy integrating STR expansion testing with PRS. Key PointsO_ST_ABSQuestionC_ST_ABSCan polygenic risk scores (PRS), alone or combined with TCF4 CTG18.1 short tandem repeat (STR) length, improve genetic risk prediction for Fuchs endothelial corneal dystrophy (FECD)? FindingsIn this GWAS meta-analysis of 7,316 cases and 1,588,467 controls, PRS showed strong predictive performance in validation cohorts lacking STR data. When STR length was available, it was the main predictor of FECD risk with limited additional contribution from PRS. Among non-expansion STR carriers, PRS helped stratify risk for broader corneal dystrophy in Europeans. MeaningPRS provide a practical, complementary approach for FECD risk prediction, particularly when STR data are unavailable.

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are cutaneous neoplasms that fall along a spectrum. PDS is more aggressive than AFX with higher rates of local and distant metastases. Diagnostic biomarkers for AFX and PDS are lacking and therefore these tumors are diagnosed only after excluding other dermal spindle cell neoplasms, including cutaneous leiomyosarcoma (cLMS), spindle cell melanoma (SCM), and sarcomatoid squamous cell carcinoma (sSCC). To identify clinically valuable biomarkers, we contrast the tumors within the diagnostic differential using single-cell RNA sequencing and bulk proteomic data. Gene Ontology (GO) analysis of transcripts and proteins enriched in AFX/PDS identified multiple shared pathways associated with cell adherence and the extracellular matrix. We identify that LRP1, LTBP2, and NAV1 are all enriched in AFX/PDS over other tumors in the differential at both the level of mRNA and protein. IHC reveals that LRP1 is 90% sensitive and 73% specific for AFX/PDS in a cohort of AFX, PDS, cLMS, SCM, and sSCC. This outperforms published data for CD10, which is currently used clinically (sensitivity 83.5% and specificity 50%). When used in conjunction with LTBP2, specificity for AFX/PDS within the differential rises from 73% to 93%. These findings suggest that LRP1, particularly if evaluated in conjunction with existing stains, can improve diagnostic accuracy for AFX and PDS.

Inactivating mutations in BRCA1-associated protein 1 (BAP1) are observed in approximately 45% of primary and [~]85% of metastatic uveal melanoma (UM) cases and are strongly correlated with aggressive phenotypes and poor prognosis. However, the mechanistic contribution of BAP1 to tumor aggressiveness remains elusive. This study investigates the role of BAP1 loss in senescence and explores the potential therapeutic implications of targeting senescence pathway. Analysis of The Cancer Genome Atlas UM cohort revealed that BAP1-mutant tumors exhibited increased senescence pathway activity score, and elevated expression of multiple cytokines, chemokines, growth factors and matrix-remodeling enzymes related to senescence-associated secretory phase. Functional assays revealed that BAP1 loss promotes senescence hallmarks including upregulated p16, p21, and phospho-ATM proteins, increased {beta}-gal positive cells, accumulated {gamma}H2AX foci, depleted lamin B1, and reduced PARP1 cleavage and Ki67 levels. These effects were further exacerbated following radiation exposure. Importantly, BAP1 knockdown, alone or in combination with ionizing radiation, sensitized UM cells to senolytic agents, dasatinib and quercetin. In conclusion, our findings identify BAP1 loss as a driver of senescence and suggest that BAP1-mutant tumors may benefit from senolytics treatment.

The continuous renewal of healthy epidermis depends on the finely regulated proliferation of basal keratinocytes and subsequent differentiation as the newly formed cells move upwards through the different layers of the epidermis. Perturbations in keratinocyte differentiation may lead to cornification disorders. We investigated seven dogs of different breeds belonging to four independent families that showed striking multifocal tree bark-like skin lesions. Histopathologically, lesional skin was characterized by pronounced epidermal and infundibular hyperkeratosis with epidermal and sebaceous gland hyperplasia. We therefore tentatively termed the phenotype phloiokeratosis, derived from the Greek word phloios for tree bark and keratosis indicating abnormal keratinization. Whole genome sequencing of DNA from affected dogs revealed four independent variants in the SUV39H1 gene encoding the SUV39H1 histone lysine methyltransferase, an H3K9 methyltransferase, which is involved in epigenetic silencing of chromatin. Phloiokeratosis is inherited as an X-chromosomal semi-dominant trait. Four of the affected dogs in our study were heterozygous females and had lesion patterns reminiscent of Blaschko lines. In two of them, trio analyses experimentally confirmed de novo mutation events in the SUV39H1 gene. Previously, Suv39h1-/- knockout mice had been reported to have normal skin. So far, no human patients with SUV39H1 loss-of-function variants have been reported. The findings in SUV39H1 mutant dogs with phloiokeratosis for the first time link SUV39H1 deficiency to a heritable skin phenotype. Our study highlights the essential role of SUV39H1-mediated epigenetic silencing during normal keratinocyte differentiation and provides a unique model for further investigations. Author SummaryThe integrity of the skin depends on a balanced equilibrium of keratinocyte proliferation, differentiation, and sloughing of terminally differentiated cells into the environment requiring finely regulated changes in the global transcriptome of differentiating keratinocytes. We investigated seven dogs belonging to four different families with a new disorder of cornification characterized by tree bark-like outgrowths of the epidermis. Histopathological examinations confirmed that the outermost layer of the epidermis was thickened in affected dogs. The genetic analysis yielded four different SUV39H1 loss-of-function variants in the affected dogs from the four families. The SUV39H1 gene encodes an enzyme that is involved in the epigenetic silencing of chromatin. The newly characterized inherited skin disease in dogs is the first clinical phenotype that has been linked to SUV39H1 deficiency. Most likely, SUV39H1 deficiency leads to delayed epigenetic silencing and consequently delayed differentiation of keratinocytes. Dogs with this rare skin disease provide an improved understanding of the essential role of SUV39H1 in the epigenetic control of gene expression in skin.

BackgroundDistinguishing benign proliferative nodules (PNs) from melanoma arising within congenital melanocytic nevi remains a major diagnostic challenge. Copy number alteration (CNA) analysis is widely used to support classification, but current criteria were developed using array comparative genomic hybridization (aCGH). The performance of alternative platforms such as shallow whole-genome sequencing (sWGS) and methylation arrays in this setting is poorly defined. ObjectivesThe objective of this study is to compare CNA profiles obtained from aCGH, sWGS, and methylation arrays in atypical nodules arising within congenital nevi, and to correlate these molecular findings with clinical outcomes. MethodsSixteen samples from fourteen patients were retrospectively analyzed using all three platforms. CNAs were cataloged, concordance across methods was quantified using the Jaccard index, and molecular classifications were compared. Clinical follow-up was reviewed to provide clinical context. ResultsaCGH detected 39 CNAs, sWGS 60, and methylation profiling 66. Concordance was highest between sWGS and methylation (mean Jaccard 0.67), followed by aCGH versus sWGS (0.64) and aCGH versus methylation (0.49). Cases with high aneuploidy demonstrated strong cross-platform agreement, whereas low-burden lesions exhibited greater variability between methods. Divergent molecular classifications were observed in six cases. ConclusionsWhile all methods reliably detect broad chromosomal changes, sWGS and methylation arrays identify many additional focal CNAs that may not align with CGH-based diagnostic criteria. Until platform-specific thresholds are established, aCGH remains the most conservative and clinically validated approach for evaluating proliferative nodules in congenital nevi. SIGNIFICANCEAccurate molecular classification of melanocytic proliferations in congenital nevi is essential but challenging, particularly in patients with multiple proliferative nodules. This study provides the first systematic comparison of aCGH, sWGS, and methylation-based CNA profiling in this setting. We show that higher-resolution platforms detect substantially more focal aberrations, which can lead to discordant and potentially overcalled malignancy assessments when applying CGH-derived criteria. Our findings highlight the need for platform-adapted diagnostic frameworks and support continued use of CGH as the most conservative and clinically validated method for risk stratification. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=118 HEIGHT=200 SRC="FIGDIR/small/26347388v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1d7b155org.highwire.dtl.DTLVardef@1bb7081org.highwire.dtl.DTLVardef@d72e3forg.highwire.dtl.DTLVardef@11d3f0b_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundThe FACE-Q Skin Cancer Module is a condition-specific patient-reported outcome measure for facial skin cancer. While its psychometric properties have been established, normative reference values that enable score interpretation in clinical practice and research are lacking. ObjectiveTo establish normative reference values for the FACE-Q Skin Cancer Module using preoperative patient data and to validate these values by comparison with a demographically matched cohort of healthy partners. MethodsTwo cohorts were analyzed: 287 patients with facial skin cancer (preoperative scores) and 82 healthy partners of skin cancer patients (same-age population without facial skin cancer). Both cohorts completed the Appearance (9 items) and Psychosocial Distress (8 items) scales. Patients additionally completed the Cancer Worry scale (10 items) and Sun Protection scale (5 items). Scores were transformed to a 0-100 scale. Normative values were expressed as percentiles overall and stratified by sex and age group. Group comparisons used independent t-tests, Mann-Whitney U tests, and Cohens d. Internal consistency was assessed with Cronbachs alpha. ResultsPatient and partner cohorts were well matched for age (68.6{+/-}11.9 vs 68.4{+/-}13.0, p=0.902) and sex (46.7% vs 41.5% female, p=0.476). Surprisingly, preoperative facial appearance scores were virtually identical between patients and partners (55.6{+/-}14.0 vs 56.6{+/-}13.6, p=0.590, d=-0.08), as were psychosocial distress scores (14.3{+/-}12.0 vs 14.4{+/-}13.3, p=0.942, d=-0.01). This equivalence held across age groups. A significant sex interaction was identified: female patients scored lower on appearance than female partners (54.3 vs 59.9, p=0.048, d=-0.40), whereas no difference existed among males (56.9 vs 53.1, p=0.168). Internal consistency was excellent in both cohorts (Cronbachs 0.82-0.93). Patients reported marginally higher sun protection behaviors than partners (38.0 vs 33.6, p=0.050). ConclusionsPreoperative FACE-Q Skin Cancer scores in patients are equivalent to those of demographically matched healthy individuals, confirming that these scores serve as valid normative references. The established percentile norms enable clinicians and researchers to interpret individual patient scores in context. The sex-specific difference in appearance scores warrants further investigation.

Melanoma is a highly plastic cancer characterized by distinct cellular phenotypes associated with broadly unique gene expression profiles. TRIM9 is a brain-enriched E3 ubiquitin ligase detected in melanoma, but how TRIM9 expression regulates melanoma phenotype is unknown. Using two metastatic human melanoma cell lines and a mouse melanoma model, we found that TRIM9 promoted melanoma proliferation and altered cell morphology. In cell lines, TRIM9 promoted cellular blebbing and negatively regulated adhesion, secretion, and mesenchymal motility. TRIM9 interacted with VASP in melanoma cells, altering VASP modification, localization, and dynamics. In the absence of TRIM9, cells had an altered actin organization and more focal adhesions, where VASP accumulated and exhibited rapid turnover. We find the alterations in actin architecture and adhesion associated with TRIM9 deletion were coincident with increased motile and contractile mesenchymal behavior in vitro. In vivo loss of TRIM9 in melanoma slowed tumor growth and altered metastasis frequency, size, and destination. Our findings indicate TRIM9 alters the proliferative and morphological phenotypes of metastatic melanoma cells to influence disease progression.

Lipoedema is a chronic adipose tissue disorder mainly affecting women with excess subcutaneous fat deposition on the lower limbs, associated with pain and tenderness. There is often a family history of lipoedema, suggesting a genetic origin, but the contribution of genetics is not well studied. We conducted a genome-wide association study (GWAS) for this disorder in a clinically ascertained cohort from Spain and performed a meta-analysis with the UK lipoedema cohort GWAS. We then used the results of this study as a replication of the inferred UK Biobank "lipoedema phenotype" study. Whilst our meta-analysis alone did not identify any genome-wide significant associations, our clinical cohorts provide support for three loci identified through the UKBB study: the chr2q24.3 GRB14-COBLL1 locus (rs6753142, PMETA=1.64x10-6), chr6p21.1 VEGFA locus (rs4711750, PMETA=8.99x10-7) and the chr5q11.2 ANKRD55-MAP3K1 locus (rs3936510, PMETA=1.67x10-5). We identify numerous rare SNPs with strong association signals in our meta-analysis (P<1x10-6) with support in both UK and Spanish datasets, three of which also show nominal support in the UKBB (P<0.05). These findings provide a starting point towards understanding the genetic basis of clinical lipoedema and demonstrate the utility of the interplay of large-scale biobanks genetic data and clinically ascertained cohorts to elucidate the genetic architecture of lipoedema.

Communication between various cell types following wounding is paramount for proper healing and regeneration of injured tissue. Endothelial cells and fibroblasts are critical cellular players involved in cutaneous wound repair, yet their communication mechanisms are not well understood. It has previously been shown that extracellular vesicles derived from endothelial cells (ECEVs) induce dermal fibroblasts to express a gene signature correlated with FGF2-mediated cancer associated fibroblast (CAF) activation, under the control of transcription factor ETV1. In this report, we utilize loss-of-function studies to define the mechanistic role of ETV1 in conferring this ECEV-induced transcriptomic shift and functional change in fibroblasts. Additionally, we identify highly expressed ECEV microRNAs and examine their potential contribution to the ECEV mechanism through downstream gene modulation. In summary, we describe a plausible mechanism by which both ETV1 and top ECEV microRNAs promote a genotypic and phenotypic shift in dermal fibroblasts that have taken up ECEVs.

Vitiligo is an acquired pigmentary disorder of the skin and mucus membranes. Previous study has demonstrated that autologous cultured epithelial grafts (ACEG) is an effective treatment for stable vitiligo. However, extraction of full-thickness skin might result in scar formation at donor site, which have hindered the wider application of this technology, especially for patients requiring large-area transplantation. Hair follicle as a source of keratinocyte and melanocyte, could be potential source of cells for preparation of autologous cultured sheet. Through culture system optimization, we have demonstrated maintenance of undifferentiated hair follicle-derived cells in feeder-independent culture system. After expansion, the hair follicle cells were directed to differentiate into a multi-layered, epidermis-like sheet. Cell identity, viability, purity, genomic stability, and antiseptic testing for hair follicle-derived epithelial sheet (HFES) were evaluated to ensure its safety. Immunofluorescence staining showed that basal keratinocytes were the main cell type of the autologous HFES. Optimization of culture conditions leads to increased melanocyte proliferation and functionality. Transcriptomic analysis confirmed upregulation of melanosome maturation genes. The proportions of cells are also similar to composition of cells under physiological conditions. Transplantation of HFES to depigmented areas in patients with stable vitiligo results in skin repigmentation. This technology provides a novel therapeutic option for vitiligo management.

Background: Facioscapulohumeral muscular dystrophy (FSHD) is a common hereditary neuromuscular disorder. The Russian FSHD Patient Registry was established in 2019 following the development of a PCR-based method for genetic confirmation of the diagnosis. Results: The registry included 470 participants (51% male). Genetic confirmation was obtained for 76% (n=356), the remainder were included based on clinical and anamnestic data. Clinical assessment forms and patient-reported questionnaires were analyzed for 310 and 142 patients, respectively. D4Z4 repeat unit (RU) distribution showed patterns consistent with European cohorts, with a predominance of patients with 3 RUs. A moderate inverse correlation was found between RUs number and clinical severity scales. Periscapular weakness was the most common onset manifestation (46.8%), followed by facial weakness (31.6%) which was often unnoticed by patients. The mean age in the Russian cohort was 37.8 years (range 0-97), indicating a younger cohort compared to international data. A delta-adjusted cluster analysis (n=215) identified three distinct trajectories: a classic phenotype with onset before age 14 and early involvement of various muscle groups (n=177), and two clusters characterized by either facial or periscapular onset with slow progression. Conclusion: The Russian FSHD registry provides a comprehensive characterization of a large national cohort, revealing a predominance of patients with 3 D4Z4 repeats and a younger demographic profile compared to international data. Cluster analysis identified three heterogeneous disease trajectories, offering a framework for improved patient stratification.

The TP53 mutation associated with Li-Fraumeni syndrome in humans is known to exhibit p53 gain-of-function properties leading to early cancer onset. To explore whether these patients also have compromised immune responses due to p53 mutations, we investigated the humoral immune response using a Li-Fraumeni mouse model harboring a structural mutation, Trp53R172H (equivalent to codon 175 in humans). Trp53R172H mice were immunized with sheep red blood cells, and the Germinal center response was monitored. Our results revealed that SRBC-immunized Trp53R172H mice exhibit reduced B cell activation during the GC reaction. These suggest a selective role for p53 in promoting B cell activation early in the GC reaction prior to BCL6 upregulation. We propose that impaired B cell activation in Li-Fraumeni patients could contribute to immune deficiencies and heightened susceptibility to autoimmune disorders, potentially influencing the development of secondary cancers and impairing therapeutic responses to chemotherapies and immunotherapies. Key PointsO_LITrp52R172H mice exhibit reduced B cell activation during the Germinal center reaction C_LIO_LIRatio of activated B cells in DZ to LZ remain unchanged in Trp52R172H mice. C_LI

Melanoma in Asia presents a unique epidemiological profile, with a higher prevalence of acral and mucosal subtypes compared to Western populations. While KIT mutations are found in up to 15% of Asian melanoma cases, clinical outcomes with KIT inhibitors have been modest due to heterogeneous mutation profiles and a lack of specific patient selection criteria. This study characterizes the landscape of KIT mutations in melanoma using the GENIE database, identifying 86 recurrent hotspots, many of which are variants of unknown significance (VUS). We validated drug sensitivities for key mutations using in vitro and in vivo models. Our results indicate that while the L576P mutation is highly sensitive to multiple inhibitors, the N822K mutation shows resistance to imatinib but responds to sunitinib, nilotinib, and nintedanib. These findings highlight the necessity of genotype-guided therapeutic strategies and provide a rationale for future clinical trials combining broad-spectrum KIT inhibitors with immune checkpoint inhibitors. Translational SignificanceMelanoma subtypes prevalent in Asia, specifically acral and mucosal melanoma, frequently harbor KIT mutations but show poor response rates (23-26%) to the standard-of-care inhibitor, imatinib. This study challenges the current clinical practice of treating all KIT-mutated melanomas uniformly. We demonstrate that specific recurrent mutations, such as N822K, are intrinsically resistant to imatinib but highly sensitive to broad-spectrum inhibitors like sunitinib and nintedanib. By establishing a comprehensive "lookup table" of drug sensitivities for both common and previously uncharacterized KIT variants, this work provides the evidence base required to transition from a "one-size-fits-all" approach to a genotype-guided precision medicine strategy. Furthermore, validating these targets informs the design of next-generation clinical trials, particularly those combining optimal KIT inhibitors with immune checkpoint blockade to improve survival in currently underserved patient populations.