Insight into innate immune response in "Yusho": The impact of natural killer cell and regulatory T cell on inflammatory prone diathesis of Yusho patients.

BACKGROUND: In 1968 in western Japan, polychlorinated biphenyl-contaminated "Kanemi rice oil" was used in cooking, causing food poisoning in many people. More than 50 years have passed since the Yusho incident, and although inflammatory disorders such as suppuration have been observed in Yusho patients, the etiology of this inflammation susceptibility remains obscure. OBJECTIVES: To investigate the mechanisms of susceptibility to inflammation in Yusho patients, peripheral immune cell fractions and concentrations of inflammatory cytokines were evaluated in blood samples collected from both Yusho patients and age-matched healthy subjects undergoing medical examination in Nagasaki. METHODS: To exclude diagnostic uncertainty, serum levels of polychlorinated biphenyl (PCB), polychlorinated quarterphenyl (PCQ), and polychlorinated dibenzofuran (PCDF) were measured. Immune cell (e.g. natural killer and regulatory T cell) populations were analyzed by flow cytometry. Serum cytokines involved in immune cell activation were measured by ELISA. RESULTS: The relative proportion of natural killer cells was higher in Yusho patients than in healthy subjects, while the proportion of regulatory T cells did not differ between groups. Serum concentrations of IL-36 and IFN-γ were significantly lower in Yusho patients than in healthy subjects. Conversely, serum cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), which is a cytokine related to activated NK cells, was higher in Yusho patients than in healthy subjects and was positively correlated with PCDF blood levels. CONCLUSION: Increased numbers of NK cells in Yusho patients suggests that the innate immune response has been activated in Yusho patients. The seemingly paradoxical results for CTLA-4 and IFN-γ may reflect counterbalancing mechanisms preventing excessive NK cell activation. This dysregulation of innate immunity might contribute to the inflammation observed in Yusho patients.

Involvement of Periostin in Skin Function and the Pathogenesis of Skin Diseases.

Skin is a large organ that is susceptible to damage by external forces, chronic inflammation, and autoimmune reactions. In general, tissue damage causes alterations in both the configuration and type of cells in lesional skin. This phenomenon, called tissue remodeling, is a universal biological response elicited by programmed cell death, inflammation, immune disorders, and tumorigenic, tumor proliferative, and cytoreductive activity. During this process, changes in the components that comprise the extracellular matrix are required to provide an environment that facilitates tissue remodeling. Among these extracellular matrix components, periostin (a glycoprotein secreted predominantly by dermal fibroblasts) has attracted much attention. In normal skin, periostin localizes mainly in the papillary dermis and basement membrane of the epidermis. However, it is expressed at higher levels in the dermis of lesional skin of those with atopic dermatitis, scars, systemic/limited scleroderma, melanoma, and cutaneous T cell lymphoma; expression is also increased by damage caused by allergic/autoimmune responses. Furthermore, periostin induces processes that result in development of dermal fibrosis; it also activates or protracts the immune response. The aim of this review is to summarize recent knowledge about the role of periostin in the pathogenesis of dermatoses.

Coexistence of keloids and pilomatricoma in a patient with Rubinstein-Taybi syndrome.

Rubinstein-Taybi syndrome (RTS) is an autosomaldominant hereditary disease, which contains many skeletal and organ anomalies as well as mental retardation. Although high incidence of keloids in RTS is known, it is difficult to find a detailed report on the clinical features of keloids. In the following letter, we report an RTS patient fulfilling diagnostic criteria whosuffered from both keloids and pilomatricoma. We also performed a literature search, which identified the possible involvement of the Wnt/ß-catenin signaling pathway in the pathogenesis of these two skin lesions.

Association of elevated α-defensin levels with interstitial pneumonia in patients with systemic sclerosis.

BACKGROUND: Interstitial lung disease (ILD) is the leading cause of mortality in patients with systemic sclerosis (SSc). Although the pathogenesis of SSc-ILD is not well understood, neutrophils may play a pivotal role in this process. Neutrophils store azurophil granules that contain defensins, antimicrobial peptides that function in regulating the inflammatory response, and IL-8, a potent chemoattractant for neutrophils. The present study evaluated the levels of defensins and IL-8 in patients with SSc-ILD to determine their roles in disease pathogenesis. METHODS: Defensins (also known as human neutrophil peptides, HNPs) and IL-8 levels were measured in the serum and bronchoalveolar lavage fluid (BALF) of 33 patients with SSc-ILD and in 20 healthy controls by using ELISA. RESULTS: BALF analysis revealed a significant increase in HNPs in SSc-ILD patients (median; 240.0 pg/mL) than that of healthy controls (79.7 pg/mL). Additionally, IL-8 levels were higher in SSc-ILD patient serum and BALF as compared to healthy controls (16.4 pg/mL vs. 5.8 pg/mL and 15.4 pg/mL vs. 14.5 pg/mL, respectively). However, plasma HNPs levels were relatively unchanged. HNP and IL-8 levels in patient BALF displayed a significant positive correlation significantly correlated (r = 0.774, p <0.01), and which also correlated with clinical disease parameters--such as ILD biomarkers, pulmonary function tests, ratio of neutrophils and eosinophils in BALF, tricuspid regurgitation peak gradient (TRPG), and the extent of high-resolution computed tomography (HRCT) findings in the lung. Levels of plasma HNPs and serum IL-8 did not show a significant correlation with any clinical parameter. SSc-ILD progression was evaluated by pulmonary function tests, but no association was observed between VC change ratios and HNPs or IL-8 levels. CONCLUSIONS: BALF levels of HNPs and IL-8 were higher in SSc-ILD than in healthy controls, and are associated with various clinical disease parameters. Further studies are needed to clarify the role of defensins and IL-8 in SSc-ILD pathogenesis.

[Serum Levels of Regulatory T Cell in the Yusho Patients].

Dioxin and dioxin-like compounds receptor (Ahr) mainly expressed on the surface of regulatory T (Treg) cell and Th17 cell could regulate immunological functions in the Yusho patients. We prospectively analyzed data obtained in a total of 56 cases of Yusho, which include patients identified ('Nintei' ) or non-identified ( 'Minintei') or identified as a family member, at the annual health check in 2014. The number of Treg cell showed lower among identified patients compared with non-identified group or family identified group (p = 0.4184 and p = 0.291, respectively). There was also a strong correlation between serum levels of neutral fat and the number of Treg cells (p = 0.0313). These results suggest that Treg cell plays a principal role in the immune response among Yusho patients.

[Serum levels of IL-21 and TGF-beta in the Yusho patients].

Aryl hydrocarbon receptor (AhR), recognized as a dioxin receptor, is expressed on the surface of helper T (Th) 17 cells. As PCBs and PCDFs are still detected in the sera of the Yusho patients, we hypothesized dysregulation of Th17 cells in the Yusho patients. In the present study, we measured IL-21 and TGF-beta in the Yusho patients which induce differentiation from Th0 to Th17 cells. Serum levels of IL-21 were lower than those of controls (p < 0.05). Meanwhile, serum levels of TGF-beta were decreased relative to controls, but not significant. These results may imply differentiation from Th0 cells to Th17 cells is not induced in the Yusho patients.

[Serum levels of IL-10 and IL-35 in Yusho patients].

We thought that dioxin and dioxin-like compound receptor AhR expressed on the surface of regulatory T (Treg) cells and Th17 cells could regulate immunological functions in the Yusho patients. In the present study, we measured Treg cell related cytokines IL-10 and IL-35 in the Yusho patients. Serum levels of IL-10 were higher, but not significant (p = 0.06), and serum levels of IL-35 were increased (p = 0.006) in comparison with healthy controls. These results imply Treg cell activation in the Yusho patients.

Paracentral acute middle maculopathy in systemic sclerosis and subsequent branch retinal artery occlusion.

Purpose: We report a case of systemic sclerosis-associated paracentral acute middle maculopathy (PAMM) in a young woman who subsequently developed branch retinal artery occlusion. Observations: A 22-year-old woman presented with a paracentral scotoma. Optical coherence tomography (OCT) revealed bilateral paracentral acute middle maculopathy. Upon systemic examination, she was diagnosed with systemic sclerosis (SSc). She subsequently developed branch retinal artery occlusion despite vasodilator medications. After the prescription of aspirin, she did not experience a new event for one year. Conclusion and importance: This case illustrates that SSc may affect the retinal vascular system and vision and cause PAMM. The optimal prophylaxis for patients with recurrent retinal events should be investigated in future studies.

Efficacy of salvage therapies for advanced acral melanoma after anti-PD-1 monotherapy failure: a multicenter retrospective study of 108 Japanese patients.

Background: Anti-programmed cell death protein 1 (PD-1) monotherapy is one of the standard systemic therapies for advanced melanoma; however, the efficacy of salvage systemic therapies after PD-1 monotherapy failure (PD-1 MF), particularly in acral melanoma (AM), the main clinical melanoma type in Japanese patients, is unclear. This study aimed to investigate the efficacy of salvage systemic therapies in Japanese patients with AM after PD-1 MF. Patients and methods: The study included 108 patients with advanced AM (palm and sole, 72; nail apparatus, 36) who underwent salvage systemic therapy at 24 Japanese institutions. We mainly assessed the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Results: Thirty-six (33%) patients received ipilimumab, 23 (21%) received nivolumab and ipilimumab (nivo/ipi), 10 (9%) received cytotoxic chemotherapy, 4 (4%) received BRAF and MEK inhibitors (BRAFi/MEKi), and the remaining 35 (32%) continued with PD-1 monotherapy after disease progression. The ORRs in the ipilimumab, nivo/ipi, cytotoxic chemotherapy, and BRAFi/MEKi groups were 8, 17, 0, and 100%, respectively. The nivo/ipi group showed the longest OS (median, 18.9 months); however, differences in ORR, PFS, and OS between the groups were insignificant. The OS in the nivo/ipi group was higher in the palm and sole groups than in the nail apparatus group (median: not reached vs. 8.7 months, p < 0.001). Cox multivariate analysis demonstrated that nail apparatus melanoma independently predicted unfavorable PFS and OS (p = 0.006 and 0.001). The total OS (from PD-1 monotherapy initiation to death/last follow-up) was insignificant between the groups. Conclusion: Nivo/ipi was not more effective than cytotoxic chemotherapy and ipilimumab after PD-1 MF in patients with advanced AM. The prognosis after PD-1 MF would be poorer for nail apparatus melanoma than for palm and sole melanoma.

Clinical practice guidelines for pseudoxanthoma elasticum (2017): Clinical Practice Guidelines for Pseudoxanthoma Elasticum Drafting Committee

Pseudoxanthoma elasticum (PXE) is a progressive hereditary disease that affects tissues such as the skin, retina, blood vessels, and gastrointestinal tracts. Therefore, comprehensive medical care across clinical departments specialized in specific organs is needed to provide the best clinical practices to PXE patients. The Japanese version of clinical guidelines developed by the Japanese Dermatological Association was published in 2017, and aimed to promote equal accessibility of PXE-related medical care. Here, the English version of Japanese guideline is reported, and is intended to be worldwide reference for medical care of PXE.

Efficacy comparison between anti-PD-1 antibody monotherapy and anti-PD-1 plus anti-CTLA-4 combination therapy as first-line immunotherapy for advanced acral melanoma: A retrospective, multicenter study of 254 Japanese patients.

BACKGROUND: Although anti-PD-1 antibody monotherapy (PD-1) is commonly used to treat advanced acral melanoma (AM), its efficacy is limited. Further, data on the efficacy of PD-1 plus anti-CTLA-4 antibody (PD-1+CTLA-4) for the treatment of AM are limited. Therefore, we compared the efficacy of PD-1+CTLA-4 and PD-1 in the treatment of Japanese patients with advanced AM. METHODS: This retrospective study evaluated patients with advanced AM who were treated with PD-1 or PD-1+CTLA-4 as first-line immunotherapy in 24 Japanese institutions between 2014 and 2020. Treatment efficacy focussing on the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) was compared between the two groups. RESULTS: In total, 254 patients (palm and sole melanoma [PSM], n = 180; nail apparatus melanoma [NAM], n = 74) were included. Among the patients with PSM, the ORR (19% vs. 31%; P = 0.44), PFS (5.9 vs. 3.2 months; P = 0.74), and OS (23.1 vs. not reached; P = 0.55) did not differ significantly between the PD-1 and PD-1+CTLA-4 groups. Among the patients with NAM, the ORR (61% vs. 10%; P < 0.001) was significantly higher and PFS was longer (6.4 vs. 3.8 months; P = 0.10) in the PD-1+CTLA-4 group than in the PD-1 group. Cox multivariate analysis demonstrated that PD-1+CTLA-4 is an independent predictor of a favourable PFS in patients with NAM (P = 0.002). CONCLUSIONS: The efficacy of PD-1+CTLA-4 is not superior to that of PD-1 for the treatment of advanced PSM. However, PD-1+CTLA-4 may be more efficacious than PD-1 for the treatment of advanced NAM.

Claudin-7 in keratinocytes is downregulated by the inhibition of HMG-CoA reductase and is highly expressed in the stratum granulosum of the psoriatic epidermis.

BACKGROUND: Cholesterol is de novo synthesized in the upper epidermis and plays an important role in maintaining the normality of skin. Studying the impact of the inhibition of cholesterol de novo synthesis in the epidermis may help understand how skin homeostasis is regulated. OBJECTIVE: In this study, we created a gene expression profile to investigate the effect of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors on epidermal homeostasis. METHODS: A microarray analysis was performed using normal keratinocytes with or without HMG-CoA reductase inhibitor (pitavastatin) treatment. Real-time PCR confirmed the reproducibility of genes with altered expression in keratinocytes treated with HMG-CoA reductase inhibitors. Among these genes, we focused on reduced expression of claudin 7 histologically confirmed by immunohistochemical staining, in situ hybridization, and immunoelectron microscopy. RESULTS: Claudin-7 was highly expressed in the stratum granulosum of psoriatic lesions but was not expressed in the normal epidermis. Immunoelectron microscopy revealed that claudin-7 was localized in the keratohyalin granules of psoriatic lesions. CONCLUSION: These results indicate that claudin-7 expression was regulated by HMG-CoA reductase in the epidermis and might play a pathogenic role in the keratohyalin granules found in the epidermal granular layer of psoriasis.

Impact of daily wearing of fabric gloves on the management of hand eczema: A pilot study in health-care workers.

Hand eczema is a major occupational disease, especially in medical workers, reducing their quality of life (QOL) and work productivity. Daily wearing of fabric gloves to prevent loss of moisture and lipids from the surface of the hands has been regarded as good in the management of hand eczema. However, limited evidence is available regarding the efficacy of moisturizing care with daily gloves on hand eczema. This pilot study was performed to evaluate the efficacy of moisturizing intervention with daily wearing of fabric gloves on skin barrier function, disease severity, and microbiome in health-care workers with hand eczema. Study 1: Nurses in the neonatal intensive care unit or growing care unit with and without hand eczema were recruited in the study. Subjects were instructed to apply moisturizer and wear two types of fabric gloves, common cotton gloves and moisturizing fabric gloves containing malate, for 4 weeks. Study 2: Physicians and health-care workers were recruited and instructed to wear a cotton glove on one hand at nighttime for 4 weeks. Disease severity, skin barrier function, QOL, and hand microbiome (Study 1) were evaluated. Study 1 found that daily wearing of both types of fabric gloves accompanied by use of topical moisturizers reduced the severity of hand eczema without changing the variation of microbiome. Study 2 found no apparent change between wearing and not wearing cotton gloves. In summary, topical moisturizer is of fundamental importance, and concomitant use of fabric gloves may merely enhance the efficacy of moisturizer in the management of hand eczema.

Real-world efficacy of anti-PD-1 antibody or combined anti-PD-1 plus anti-CTLA-4 antibodies, with or without radiotherapy, in advanced mucosal melanoma patients: A retrospective, multicenter study.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have a lower efficacy in mucosal melanoma (MUM) than in cutaneous melanoma. The use of combination treatments with radiotherapy (RT) to improve the efficacy in MUM, however, requires further investigation. METHODS: We retrospectively evaluated 225 advanced MUM patients treated with anti-PD-1 monotherapy (PD1; 115) or anti-PD-1 + anti-CTLA-4 combination therapy (PD1+CTLA4; 42) with or without RT (56 and 12, respectively). Treatment efficacy was estimated by determining the objective response rate (ORR) and survival rate with the Kaplan-Meier analysis. RESULTS: The baseline characteristics between the two groups in each ICI cohort were similar, except for Eastern Cooperative Oncology Group performance status in the PD1 cohort. No significant differences in ORR, progression-free survival (PFS), and overall survival (OS) were observed between the PD1 alone and PD1+RT groups in the PD1 cohort (ORR 26% versus 27%, P > 0.99; median PFS 6.2 versus 6.8 months, P = 0.63; median OS 19.2 versus 23.1 months, P = 0.70) or between the PD1+CTLA alone and PD1+CTLA4+RT groups in the PD1+CTLA4 cohort (ORR 28% vs 25%, P = 0.62; median PFS 5.8 versus 3.5 months, P = 0.21; median OS 31.7 versus 19.8 months, P = 0.79). Cox multivariate analysis indicated that RT in addition to PD1 or PD1+CTLA4 did not have a positive impact on the PFS or OS. CONCLUSIONS: A prolonged survival benefit with RT in combination with ICIs was not identified for advanced MUM patients, although RT may improve local control of the tumour and relieve local symptoms.

Systemic treatment of patients with advanced cutaneous squamous cell carcinoma: response rates and outcomes of the regimes used.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is the second most common type of skin cancer. Few patients with cSCC experience metastases, but the prognosis of advanced cSCC (acSCC) is dismal. Evidence regarding systemic therapy for acSCC is limited. Therefore, we aimed to determine the most effective systemic treatment for acSCC. PATIENTS AND METHODS: This retrospective study involved 16 Japanese institutions. We documented patient and tumour characteristics and disease course of patients with acSCC who received systemic therapy between 1st January 2006 and 31st December 2015. We compared the overall survival (OS) and progression-free survival (PFS) for (1) platinum versus non-platinum groups, (2) radiation plus chemotherapy first-line therapy (RCT) versus non-RCT groups and (3) platinum-based RCT versus non-platinum-based RCT groups. RESULTS: Although the use of platinum-based systemic therapy was not associated with statistically significant improvements in PFS and OS, there were significant differences between the RCT and non-RCT groups (PFS: p < 0.001, OS: p = 0.003). In the subgroup analysis, RCT significantly prolonged PFS and OS in the nodal SCC (nSCC) group. For the RCT and non-RCT groups, the median OS was 110 and 14 months, respectively, and the 5-year OS rate was 54% and 21%, respectively. CONCLUSION: RCT could improve OS in patients with nSCC. However, further multicenter prospective studies are needed to establish evidence for superiority of RCT.

Clinical and histopathological significance of PD-1 expression in cutaneous lesions of adult T-cell leukemia-lymphoma.

BACKGROUND: Adult T-cell leukemia-lymphoma (ATL) is a mature T-cell malignancy caused by human T-cell leukemia virus type I infection and is known to exhibit cutaneous involvement in 50% or more patients. Few studies have evaluated the clinicopathological significance of programmed death-1 (PD-1) expression in the cutaneous lesions of ATL. METHODS: Skin biopsy specimens from 29 ATL patients with cutaneous lesions were evaluated regarding the clinicopathological feature, survival outcome, and PD-1 expression level on infilitrated CD3+CD4 + CD25+ cells. The optimal cut-off point of PD-1 expression for clinicopathological feature and outcome was determined as the value of the maximum Youden index by receiver operating characteristic (ROC) analysis. RESULTS: PD-1 was expressed broadly from zero to 90% on the skin biopsy specimens of the 29 patints, with the median value of 50%. The PD-1-expression level was significantly higher in the poorer-prognosis eruption group (nodulotumoral, erythrodermic and purpuric types) (P = 0.003), in the poorer histopathological infiltration patterns (diffuse and nodular) (P = 0.007), and in the poorer infiltrating cell-size group (large-sized cells) (P = 0.017) than in the corresponding group. ROC curve analyses showed that the optimal cut-off value for PD-1-expression level to predict the poorer-prognosis eruption, the poorer- histopathological infiltration pattern, the poorer infiltration cell size, and the poorer outcome (death) was 60%, 50%, 50%, and 80%, respectively. Patients with high PD-1 expression had a shorter median survival time than those with low PD-1 expression (18.2 months vs. 26.0 months), but the difference was not statistically significant. CONCLUSIONS: ATL patients with cutaneous lesions in which PD-1 were highly expressed have more advanced dermatological and histopathological patterns and possibly worse survival than those with low PD-1 expression on cutaneous lesions. Further large-scale studies are warranted to verify these findings.

Diffuse alveolar hemorrhage with pseudoprogression during nivolumab therapy in a patient with malignant melanoma.

Nivolumab, an anti-PD-1 antibody, has been shown to be effective in many cancers, such as malignant melanoma and lung cancer; however, nivolumab therapy can result in pseudoprogression. Diffuse alveolar hemorrhage (DAH) is persistent or recurrent pulmonary hemorrhage as a result of drugs, autoimmune diseases, or infections. DAH with pseudoprogression during nivolumab administration has rarely been reported. Herein, we describe our experience with one such case. A 41-year-old woman exhibited bloody sputum and ground glass opacities in the lungs along with tumor growth during nivolumab therapy for multiple lung metastases of malignant melanoma. We diagnosed DAH with pseudoprogression as a result of nivolumab and administered steroid therapy. The DAH subsequently improved and the tumor shrank. This case illustrates that nivolumab can cause DAH with pseudoprogression, which can be controlled by steroid therapy. Thus, if bloody sputum and ground glass opacities in the lungs are observed with tumor growth during nivolumab administration, steroid therapy should be considered to control DAH with pseudoprogression.

Calcification in dermal fibroblasts from a patient with GGCX syndrome accompanied by upregulation of osteogenic molecules.

Gamma-glutamyl carboxylase (GGCX) gene mutation causes GGCX syndrome (OMIM: 137167), which is characterized by pseudoxanthoma elasticum (PXE)-like symptoms and coagulation impairment. Here, we present a 55-year-old male with a novel homozygous deletion mutation, c.2,221delT, p.S741LfsX100, in the GGCX gene. Histopathological examination revealed calcium deposits in elastic fibers and vessel walls, and collagen accumulation in the mid-dermis. Studies of dermal fibroblasts from the patient (GGCX dermal fibroblasts) demonstrated that the mutated GGCX protein was larger, but its expression level and intracellular distribution were indistinguishable from those of the wild-type GGCX protein. Immunostaining and an enzyme-linked immunosorbent assay showed an increase in undercarboxylated matrix gamma-carboxyglutamic acid protein (ucMGP), a representative substrate of GGCX and a potent calcification inhibitor, indicating that mutated GGCX was enzymatically inactive. Under osteogenic conditions, calcium deposition was exclusively observed in GGCX dermal fibroblasts. Furthermore, GGCX dermal fibroblast cultures contained 23- and 7.7-fold more alkaline phosphatase (ALP)-positive cells than normal dermal fibroblast cultures (n = 3), without and with osteogenic induction, respectively. Expression and activity of ALP were higher in GGCX dermal fibroblasts than in normal dermal fibroblasts upon osteogenic induction. mRNA levels of other osteogenic markers were also higher in GGCX dermal fibroblasts than in normal dermal fibroblasts, which including bone morphogenetic protein 6, runt-related transcription factor 2, and periostin (POSTN) without osteogenic induction; and osterix, collagen type I alpha 2, and POSTN with osteogenic induction. Together, these data indicate that GGCX dermal fibroblasts trans-differentiate into the osteogenic lineage. This study proposes another mechanism underlying aberrant calcification in patients with GGCX syndrome.

Analysis of clinical symptoms and ABCC6 mutations in 76 Japanese patients with pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is a hereditary disease, causing calcification and degeneration of elastic fibers, which affects the skin, eye, cardiovascular systems and gastrointestinal tract. PXE is caused by mutations in the ABCC6 gene. Neither detailed nor large-scale analyses have been accomplished in Japanese patients with PXE. We, therefore, investigated clinical symptoms and ABCC6 gene mutations in 76 Japanese patients. Japanese PXE patients (n = 76) had a significantly lower incidence of vascular lesions than 505 PXE patients in the Leiden Open Variation Database (LOVD) (38.7% vs 65.1%, respectively; P = 1.34E-06); however, the incidences of the skin, eye, cardiac and gastrointestinal lesion symptoms were not significantly different. Symptom severity scores for skin, eye and vascular lesions, calculated using the Phenodex™ system, were significantly lower in Japanese PXE patients than in LOVD PXE patients. Genetic analysis revealed three nonsense, four frame-shift, one exon deletion and 13 missense mutations in ABCC6 in 73 patients; however, we were unable to detect pathogenic mutations in three patients. Frequent mutations differed between Japanese and LOVD PXE patients. In Japanese PXE patients, the top five mutations accounted for more than 60% of all pathogenic changes, suggesting the presence of founder effects. Consistent with previous reports, no obvious correlations between genotypes and phenotypes were identified in this study. In conclusion, we consider that the milder clinical phenotypes, observed even in older Japanese PXE patients, could be attributed to environmental factors such as dietary habits and lifestyle, as well as genetic background.