Loss-of-function variants in GLMN are associated with generalized skin hyperpigmentation with or without glomuvenous malformation.

BACKGROUND: Inherited hyperpigmented skin disorders comprise a group of entities with considerable clinical and genetic heterogenicity. The genetic basis of a majority of these disorders remains to be elucidated. OBJECTIVES: This study aimed to identify the underlying gene for an unclarified disorder of autosomal-dominant generalized skin hyperpigmentation with or without glomuvenous malformation. METHODS: Whole-exome sequencing was performed in five unrelated families with autosomal-dominant generalized skin hyperpigmentation. Variants were confirmed using Sanger sequencing and a minigene assay was employed to evaluate the splicing alteration. Immunofluorescence and transmission electron microscopy (TEM) were used to determine the quantity of melanocytes and melanosomes in hyperpigmented skin lesions. GLMN knockdown by small interfering RNA assays was performed in human MNT-1 cells to examine melanin concentration and the underlying molecular mechanism. RESULTS: We identified five variants in GLMN in five unrelated families, including c.995_996insAACA(p.Ser333Thrfs*11), c.632 + 4delA, c.1470_1473dup(p.Thr492fs*12), c.1319G > A(p.Trp440*) and c.1613_1614insTA(Thr540*). The minigene assay confirmed that the c.632 + 4delA mutant resulted in abolishment of the canonical donor splice site. Although the number of melanocytes remained unchanged in skin lesions, as demonstrated by immunofluorescent staining of tyrosinase and premelanosome protein, TEM revealed an increased number of melanosomes in the skin lesion of a patient. The GLMN knockdown MNT-1 cells demonstrated a higher melanin concentration, a higher proportion of stage III and IV melanosomes, upregulation of microphthalmia-associated transcription factor and tyrosinase, and downregulation of phosphorylated p70S6 K vs. mock-transfected cells. CONCLUSIONS: We found that loss-of-function variants in GLMN are associated with generalized skin hyperpigmentation with or without glomuvenous malformation. Our study implicates a potential role of glomulin in human skin melanogenesis, in addition to vascular morphogenesis.

A group of skin conditions known as 'inherited hyperpigmented skin disorders' includes some diseases with different clinical and genetic traits. The genetic basis of the majority of these diseases is not understood. To identify the gene responsible for a disease that causes darker patches of skin (hyperpigmentation) with or without the abnormal growth of blood vessels and the presence of cells named glomus cells (a glomuvenous malformation), we used genetic techniques called whole-exome sequencing and Sanger sequencing in five unrelated families with this disease. We also used a technique called a 'minigene assay' to evaluate genetic alterations in a gene called GLMN, which encodes a protein called glomulin. Immunofluorescence and transmission electron microscopy (TEM) were used to determine the number of pigment-producing cells (called melanocytes) and melanosomes (where the pigment melanin is synthesized, stored and transported) in hyperpigmented skin lesions. We identified five different variants of the GLMN gene in five unrelated families. Although the number of melanocytes remained unchanged in skin lesions, TEM revealed an increased number of melanosomes. By 'switching off' the GLMN gene, we found that skin cells produced more pigment, as well as the proteins MITF and tyrosinase; they also showed a decrease in the phosphorylated protein p-p70S6 K. Overall, we found that loss-of-function mutations in GLMN caused skin hyperpigmentation with or without abnormal blood vessels. The results suggest there could be a potential role of the protein glomulin in human skin colour and blood vessel changes.

Cases with the H syndrome presenting with skin and bone findings.

BACKGROUND: The H syndrome is an autosomal recessive disease characterized by hyperpigmentation, hypertrichosis and sensorineural hearing loss. METHODS: A mutation in the coding of the human equilibrative nucleoside transporter 3 (hENT3) within the SLC29A3 gene on chromosome 10q22 leads to the manifestation of this disease. In this report, we present two cases of H syndrome. RESULTS: The first patient exhibits hyperpigmentation, hypogonadism, Type 1 diabetes mellitus, arthritis and osteoporosis. The second patient experiences hyperpigmentation, hypertrichosis, osteopenia and hypogonadism. CONCLUSION: Our objective is to broaden the clinical spectrum of H syndrome, highlighting the involvement of arthritis, hyperinflammation and low bone mineral density in individuals with this disorder.

Major histocompatibility complex (MHC) gene frequency in acquired dermal macular hyperpigmentation: a case control study.

BACKGROUND: Human leukocyte antigen (HLA) allele frequencies have a known association with the pathogenesis of various autoimmune diseases. METHODS: We recruited 31 Indian patients of acquired dermal macular hyperpigmentation (ADMH) and 60 unrelated, age-and-gender-matched healthy controls. After history and clinical examination, 5 ml of blood in EDTA vials was collected. These samples were subjected to DNA extraction and the expression of HLA A, B, C, DR, DQ-A, and DQ-B was studied. RESULTS: There was a predominance of females with a gender ratio of 23 : 8 and the most common phototype was Fitzpatrick type IV (83.9%). There was a significant association of HLA A*03:01 (OR: 5.8, CI: 1.7-17.0, P = 0.005), HLA B*07:02 (OR: 5.3, CI: 1.9-14.6, P = 0.003), HLA C*07:02 (OR: 4.3, CI: 1.8-9.6, P = 0.001), HLA DRB1*10:01 (OR: 7.6, CI: 1.7-38.00, P = 0.022), and HLA DRB1*15:02 (OR: 31.0, CI: 4.4-341.8, P < 0.001) with patients compared to controls, whereas HLA DQB*03:01 was less associated with patients compared to controls (OR: 0.2, CI: 0.0-0.6, P = 0.009). CONCLUSION: Patients with ADMH are more likely to have the HLA A*03:01, HLA B 07*02, HLA C*07:02, HLA DRB1*10:01, HLA DRB1*15:02 and less likely to have the HLA DQB*03:01 allele. Larger cohort studies may thus be conducted studying these specific alleles.

Hyperglycemia with hypogonadism and growth hormone deficiency in a 17-year-old male with H syndrome: the first case report from Syria.

BACKGROUND: The nucleoside transport capabilities of the human equilibrative nucleoside transporter-3 (hENT3) are disrupted by mutations in SLC29A3 (10q22.2), which are genes for the nucleoside transporter and are the cause of the unusual autosomal recessive disease known as H syndrome. As a result, histiocytic cells invade a number of organs. CASE PRESENTATION: A 17-year-old Syrian male was admitted to the internal medicine department with a one-month history of polyuria, polydipsia, general weakness, and pallor. He had a history of progressive bilateral sensorineural hearing loss and failure to gain weight for three years. Physical examination revealed various abnormalities, including scrotal mass, small penis and testicles, absence of pubic and axillary hair, joint abnormalities, short stature, hallux valgus, fibrous protrusion near the navel, and hyperpigmented non-itchy painful skin plaques. Clinical signs along with laboratory test results confirmed hyperglycemia, primary hypogonadism, osteopenia, and growth hormone deficiency. After a review of the relevant medical literature, this patient's presentation of hyperglycemia with hypogonadism, hyperpigmentation, hallux valgus, hearing loss, hematological abnormalities, and short stature suggested the diagnosis of H syndrome. The patient received treatment with insulin and testosterone, leading to a significant improvement in his presenting symptoms. CONCLUSIONS: H syndrome is a very rare condition, and the fact that the first case has only recently been reported in Syria serves to emphasize how rare it is. H Syndrome should be suspected if a patient has short stature with signs of hyperglycemia and other endocrine and cutaneous abnormalities. We are reporting this case to increase physicians' awareness of this exceedingly rare and unique syndrome.

Dyschromatosis universalis hereditaria.

Reticulate pigmentary dyschromatoses primarily include dyschromatosis universalis hereditaria (DUH), dyschromatosis symmetrica hereditaria (DSH) (Reticulate acropigmentation of Dohi), and unilateral dermatomal pigmentary dermatosis, which differ in their patterns of distribution. The disease was initially described by Ichikawa and Hiraga in Germany in 1933. The prevalence of DUH is 0.3 per 100,000 with a female preponderance. The skin lesions usually appear in infancy or early childhood and cease to progress beyond adolescence. The subtypes DUH 1 and DUH 3 are found to have autosomal dominant inheritance, which is the most common inheritance pattern, while DUH 2 has an autosomal recessive pattern. The most common gene involved in DUH is ABCB6, while the other genes include SASH 1, PER 3, and KITLG (DUH type 2). DUH is characterized by multiple irregular hyperpigmented macules interspersed with hypopigmented macules in a mottled pattern over the trunk and extremities. The face is involved in 50% of individuals. Rarely, it can also involve hairs, nails, mucous membranes, palms, and soles. Other varied presentations include localized forms, localization of lesions to sun-exposed areas, large macules, uniform palmar hypopigmentation, diffuse hyperpigmentation with spotty depigmented macules, and unilateral involvement. DUH has been reported to be associated with various cutaneous and systemic diseases. The authors have observed cases of DUH associated with hepatocellular carcinoma, solitary keratoacanthoma, and dermoid cyst. The various diagnostic modalities include dermoscopy, histopathology, electron microscopy, and targeted gene sequencing. Though various treatment modalities like NBUVB and lasers have been tried, no treatment is promising.

Inherited Reticulate Pigmentary Disorders.

Reticulate pigmentary disorders (RPDs) are a group of inherited and acquired skin conditions characterized by hyperpigmented and/or hypopigmented macules. Inherited RPDs include dyschromatosis symmetrica hereditaria (DSH), dyschromatosis universalis hereditaria (DUH), reticulate acropigmentation of Kitamura (RAK), Dowling-Degos disease (DDD), dyskeratosis congenita (DKC), Naegeli-Franceschetti-Jadassohn syndrome (NFJS), dermatopathia pigmentosa reticularis (DPR), and X-linked reticulate pigmentary disorder. Although reticulate pattern of pigmentation is a common characteristic of this spectrum of disorders, the distribution of pigmentation varies among these disorders, and there may be clinical manifestations beyond pigmentation. DSH, DUH, and RAK are mostly reported in East Asian ethnicities. DDD is more common in Caucasians, although it is also reported in Asian countries. Other RPDs show no racial predilection. This article reviews the clinical, histological, and genetic variations of inherited RPDs.

Retyping and molecular pathology diagnosis of dyschromatosis universalis hereditaria.

Dyschromatosis universalis hereditaria (DUH) is characterized by diffuse symmetrically distributed hypopigmented macules mixed with hyperpigmentation. DUH is divided into three types by Online Mendelian inheritance in man (OMIM) that is, DUH1 (OMIM 127500), DUH2 (OMIM 612715) and DUH3 (OMIM 615402) according to the different linkage regions. Although each condition possesses corresponding phenotypic characteristics and the prognosis for each is somewhat different, these disorders are highly overlapped and difficult to differentiate in the clinical setting. Our latest study reveals a novel DUH subtype that presents a mild phenotype of pigmentation anomalies and is named PER3rs772027021 SNP related DUH or DUH4 by us, which make the DUH subtype can be further retyped. Heterozygous distribution or mosaic-like distribution of melanin is a newly discovered pathological features that is uniquely demonstrated in the affected layers of DUH1 and DUH4 patients. In this review, DUH is further divided into four subtypes according the causative genes and their mutational sites, and the mutation regions described in the previous reports. To make an accurate diagnosis, we suggest that Sanger sequencing or the target region sequencing (TRS) to the candidate causative genes related melanogenesis may be the most effective and convenient method of clinical diagnosis or/and prenatal diagnosis for DUH and DUH-like patients. More importantly, heterozygous distribution or mosaic-like distribution of melanin can be utilized for differential diagnosis of DUH. We also investigate the underlying molecular mechanism to form mosaic-like melanin in the affected layers of hyper- and/or hypo-pigmented macules from DUH1 and DUH4 patients. This review provides a molecular and pathological delineation of four types of DUH and aims to establish a concise diagnostic strategy to allow clinical dermatologists to make an accurate diagnosis.

Laser-assisted drug delivery of synthetic alpha melanocyte stimulating hormone and L-tyrosine leads to increased pigmentation area and expression of melanogenesis genes in a porcine hypertrophic scar model.

OBJECTIVES: One symptom of hypertrophic scar (HTS) that can develop after burn injury is dyschromia with hyper- and hypopigmentation. There are limited treatments for these conditions. Previously, we showed there is no expression of alpha melanocyte stimulating hormone (α-MSH) in hypopigmented scars, and if these melanocytes are treated with synthetic α-MSH in vitro, they respond by repigmenting. The current study tested the same hypothesis in the in vivo environment using laser-assisted drug delivery (LADD). METHODS: HTSs were created in red Duroc pigs. At Day 77 (pre), they were treated with CO2 fractional ablative laser (FLSR). Synthetic α-MSH was delivered as a topical solution dissolved in  l-tyrosine (n = 6, treated). Control scars received LADD of  l-tyrosine only (n = 2, control). Scars were treated and examined weekly through Week 4. Digital images and punch biopsies of hyper, hypo-, and normally pigmented scar and skin were collected. Digital pictures were analyzed with ImageJ by tracing the area of hyperpigmentation. Epidermal sheets were obtained from punch biopsies through dispase separation and RNA was isolated. qRT-PCR was run for melanogenesis-related genes: tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1), and dopachrome tautomerase (DCT). Two-way ANOVA with multiple comparisons and Dunnett's correction compared the groups. RESULTS: The areas of hyperpigmentation were variable before treatment. Therefore, data is represented as fold-change where each scar was normalized to its own pre value. Within the LADD of NDP α-MSH + l-tyrosine group, hyperpigmented areas gradually increased each week, reaching 1.3-fold over pre by Week 4. At each timepoint, area of hyperpigmentation was greater in the treated versus the control (1.04 ± 0.05 vs. 0.89 ± 0.08, 1.21 ± 0.07 vs. 0.98 ± 0.24, 1.21 ± 0.08 vs. 1.04 ± 0.11, 1.28 ± 0.11 vs. 0.94 ± 0.25; fold-change from pre-). Within the treatment group, pretreatment, levels of TYR were decreased -17.76 ± 4.52 below the level of normal skin in hypopigmented scars. After 1 treatment, potentially due to laser fractionation, the levels decreased to -43.49 ± 5.52. After 2, 3, and 4 treatments, there was ever increasing levels of TYR to almost the level of normally pigmented skin (-35.74 ± 15.72, -23.25 ± 6.80, -5.52 ± 2.22 [p < 0.01, Week 4]). This pattern was also observed for TYRP1 (pre = -12.94 ± 1.82, Week 1 = -48.85 ± 13.25 [p < 0.01], Weeks 2, 3, and 4 = -34.45 ± 14.64, -28.19 ± 4.98, -6.93 ± 3.05 [p < 0.01, Week 4]) and DCT (pre = -214.95 ± 89.42, Week 1 = -487.93 ± 126.32 [p < 0.05], Weeks 2, 3, and 4 = -219.06 ± 79.33, -72.91 ± 20.45 [p < 0.001], -76.00 ± 24.26 [p < 0.001]). Similar patterns were observed for scars treated with LADD of  l-tyrosine alone without NDP α-MSH. For each gene, in hyperpigmented scar, levels increased at Week 4 of treatment compared to Week 1 (p < 0.01). CONCLUSIONS: A clinically-relevant FLSR treatment method can be combined with topical delivery of synthetic α-MSH and l-tyrosine to increase the area of pigmentation and expression of melanogenesis genes in hypopigmented HTS. LADD of  l-tyrosine alone leads to increased expression of melanogenesis genes. Future studies will aim to optimize drug delivery, timing, and dosing.

Clinical characteristics of 47 children with pigmentary mosaicism: A cross-sectional study.

BACKGROUND: Pigmentary mosaicism (PM), also known as Blaschkoid dyspigmentation, is a rare pigmentary anomaly. Although several case reports have been published describing extracutaneous manifestations associated with PM, there are very few studies on the clinical characteristics of patients with PM. AIM: To describe the clinical characteristics of patients with PM. PATIENTS AND METHODS: This descriptive cross-sectional study was conducted among 47 children examined by a dermatologist and a pediatrician. The pattern and location of the PM, type of pigmentation and extracutaneous manifestations were documented. RESULTS: The most common pattern of PM was narrow-band PM, followed by broad-band and checkerboard patterns. The trunk was the most affected region, followed by the legs and arms. PM manifested as hypopigmentation in 51.1% of cases, as hyperpigmentation in 27.6%, and as hypo/hyperpigmentation in 21.2%. Accompanying diseases were present in 40.4% of patients: neuropsychiatric diseases were the most common, followed by endocrinological or hematological diseases and growth/developmental delay. CONCLUSION: PM has been associated with several extracutaneous findings but there is still some debate whether these associations reflect different PM phenotypes or whether they are simply coincidental. Our study suggests that extracutaneous involvement in PM patients is frequent, thus warranting careful examination of PM patients.

KRT5 mutation regulate melanin metabolism through notch signalling pathway between keratinocytes and melanocytes.

Dowling-Degos disease (DDD) is an autosomal dominant hereditary skin disease characterized by acquired reticular hyperpigmentation in flexural sites, and one of its causative genes is KRT5 gene. But the effect of KRT5, expressed only in keratinocytes, on melanocytes is unclear. Other pathogenic genes of DDD include POFUT1, POGLUT1 and PSENEN genes, which is involved in posttranslational modification of Notch receptor. In this study, we aim to determine the ablation of keratinocyte KRT5 affect melanogenesis in melanocyte through Notch signalling pathway. Here we found that KRT5 downregulation decreased the expression of the Notch ligand in keratinocytes and Notch1 intracellular domain in melanocytes, by establishing two cell models of ablation of KRT5 in keratinocytes based on CRISPR/Cas9 site-directed mutation and lentivirus-mediated shRNA. Treatment of melanocytes with Notch inhibitors had same effects with ablation of KRT5 on increase of TYR and decrease of Fascin1. Activation of Notch signalling reverses the effect of ablation of KRT5 on melanogenesis. Immunohistochemistry of DDD lesions with KRT5 gene mutation confirmed changes in the expression of relevant molecules in Notch signalling. Our research elucidates molecular mechanism of KRT5-Notch signalling pathway in the regulation of melanocytes by keratinocytes, and preliminary reveal the mechanism of DDD pigment abnormality caused by KRT5 mutation. These findings identify potential therapeutic targets of the Notch signalling pathway for the treatment of skin pigment disorders.

The PER3rs772027021 SNP induces pigmentation phenotypes of dyschromatosis universalis hereditaria.

Dyschromatosis universalis hereditaria (DUH) is a pigmentary genodermatosis characterized by a mixture of hyperpigmented and hypopigmented macules distributed randomly over the body. Although Sterile Alpha motif- and SH3 domain-containing protein 1 (SASH1) and ATP-binding cassette subfamily B, member 6 (ABCB6) have been identified as causative genes for this disorder, some cases involve unknown pathogenic genes. In this study, whole-exome sequencing, data analysis, and Sanger sequencing were utilized for a four-generation extended Chinese family with DUH. A single-nucleotide polymorphism (SNP) (c. 517C > T (p.P173S), rs772027021) variant in exon 5 of Period Circadian Regulator 3 (PER3) (NM_001289861) was detected in each affected individual of the DUH family; the c. 517C > T SNP of PER3 (PER3rs772027021 SNP) and a novel mutation in exon 14 of SASH1 (c. 1574C > G (p.T525R)) were both found in the proband. The affected individuals carrying PER3rs772027021 SNP in this family demonstrated mild-pigmented phenotypes compared to those of the proband carrying PER3rs772027021 SNP and SASH1 T525R mutation. Increased melanin synthesis was induced by PER3rs772027021 SNP in the melanocytes of affected epithelial tissues. Mutated SASH1 or PER3rs772027021 SNP alone or cooperation of mutation of SASH1 and PER3rs772027021 SNP synergistically led to increased melanin synthesis and enhanced proliferation of melanoma cells in vitro. We also phenotypically characterized a commercially available zebrafish mutant line harboring the PER3rs772027021 SNP to induce melanocyte proliferation in vivo. Our results are the first to reveal that this PER3 SNP may be pathogenic for a novel DUH subtype with mild hyperpigmented and/or hypopigmented phenotypes and that mutation of SASH1 and PER3 cooperatively promotes hyperpigmentation phenotypes. KEY MESSAGES: PER3 rs772027021 SNP is identified to be associated with hyperpigmentation and/or hypopigmentation phenotype and the novel pathogenic variant of PER3 rs772027021 SNP probably contributed the pathogenesis of DUH. SASH1T525R mutation is confirmed to associate with DUH. A novel autosomal dominant inheritance DUH subtype with mild pigmentated phenotypes is caused by the PER3rs772027021 SNP.

Chinese Pedigree with Hereditary Gastrointestinal Stromal Tumors: A Case Report and Literature Review.

Familial gastrointestinal stromal tumor (GIST) is a rare autosomal dominant genetic disorder with only a few affected families reported to date. Here, we report a case of familial GISTs harboring a novel germline mutation within exon 18 of KIT. A 58-year-old male patient presented with gastric subepithelial lesions accompanied by cutaneous hyperpigmentation, which were subsequently diagnosed as multinodular GISTs. Endoscopic surgery was initially conducted to remove the larger lesions, and pathological examinations were then conducted for the diagnosis of GISTs. Family history revealed that some other family members had similar cutaneous pigmentations. Whole-exome sequencing was used to search for potential driver mutations, and Sanger sequencing was used for mutation validation. A novel primary driver mutation of KIT (c.G2485C, p.A829P) was detected in these hereditary GISTs, which has been reported in some targeted chemotherapy-resistant GISTs. Cell models were subsequently established for the rapid screening of candidate drugs and exploring potential mechanisms. This mutation could lead to cell proliferation and imatinib resistance by ligand-independent activation of KIT; however, ripretinib administration was identified as an applicable targeted therapy for this mutation. The mutation activated the JAK/STAT3 and MAPK/ERK pathways, which could be inhibited by ripretinib administration. To the best of our knowledge, this is the first report of the KIT-A829P mutation in familial GISTs, complementing the pathogenesis of familial GISTs and providing valuable information for the precision treatment of this disease.

Happle-Tinschert syndrome variable phenotype as part of the mosaic hedgehog spectrum: Report of three cases.

Happle-Tinschert syndrome is a rare genodermatosis caused by a postzygotic mutation in SMO gene. The most recognized clinical findings include segmentally arranged basaloid follicular hamartomas, nevoid hypertrichosis, linear atrophoderma, and hypopigmentation or hyperpigmentation following Blaschko lines associated with osseous, dental, and cerebral alterations. We report three additional cases, two of which lacked the pathognomonic basaloid follicular hamartomas, with genetic confirmation and detailed clinical characterization and describe new cutaneous features of this infrequent syndrome.

Renal Involvement in H Syndrome, A Rare Cause of Diabetes Mellitus: Case Report.

BACKGROUND: H syndrome is a rare genodermatosis deriving from a mutation in the SLC29A3 gene and affecting numerous systems, particularly the skin. The syndrome exhibits different clinical characteristics involving several systems, most beginning with the letter "H." The most common clinical findings are cutaneous hyperpigmentation, flexion contracture in the fingers, hearing loss, short stature, insulin-dependent diabetes mellitus, heart anomalies, hepatosplenomegaly, and hypogonadism. Fewer than 150 cases have been reported so far and vast majority of them consisted with patients with Arab ethnicity. CASE PRESENTATION: We describe a patient presenting with short stature, developing diabetes mellitus at follow-ups, with homozygous deletion determined in exon 3 of the SLC29A3 gene, and diagnosed with H syndrome, reported due to the presence and rarity of renal involvement (hematuria and proteinuria). CONCLUSION: In conclusion, despite its rarity, endocrinologists, rheumatologists/nephrologists, and dermatologists need to be aware of H syndrome as a pleiotropic syndrome. H syndrome should be considered in the differential diagnosis of patients with cutaneous hyperpigmentation (particularly in the bilateral thigh and calf region) together with proteinuria/hematuria. In addition, periodic urine analysis should be performed in patients with H syndrome.