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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., (© 2024 Australasian College of Dermatologists.)

Background: Pigmentary hypertrichosis and non-autoimmune insulin-dependent diabetes mellitus (PHID) is one of the rare H syndrome diseases mainly characterized by hyperpigmentation, hypertrichosis, sensorineural hearing loss, cardiac complications, developmental delay, and diabetes mellitus (DM). Mutations in the coding regions of the SLC29A3 gene that encodes for an equilibrative nucleoside transporter (ENT3) have been reported to cause the phenotypic spectrum of the H syndrome. Disease-causing mutations in the untranslated regions (UTRs) of the SLC29A3 gene have not been previously described in the literature. The aim of the study is to describe and assess the pathogenicity of a novel 3'UTR mutation in the SLC29A3 gene associated with the PHID phenotype in two Turkish patients., Methods: The mutation was identified by a targeted gene approach. To understand the pathogenicity of this 3'UTR mutation, RNA and protein expression studies were performed by using the quantitative real-time polymerase chain reaction method and western blotting, respectively, using fibroblasts cultured from the patients' skin biopsies., Results: SLC29A3 and ENT3 expression levels were both decreased in the patients compared to controls matched for passage numbers, RNA, and protein extraction methods., Conclusions: A novel 3'UTR mutation in the SLC29A3 gene is associated with the PHID syndrome, highlighting a potentially new pathological mechanism for this disease. The involvement of the 3'UTR has not been previously established in any of the H syndrome disease cluster or in any complex syndrome of DM., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

H syndrome is a rare monogenic autosomal recessive disease with characteristic cutaneous findings and multisystem involvement. The aim of this study is to present an Iranian patient with H syndrome and to describe a novel frameshift mutation in SLC29A3 gene. The patient was diagnosed with a few small areas of hyperpigmentation and accompanying hypertrichosis in the lumbar area of her back. Her clinical phenotypes included short stature, hepatosplenomegaly, facial widespread bilateral telangiectatic lesions, bilateral hypertrophy of the parotid gland, upper extremity flexion contracture, elevated inflammatory markers (ESR, CRP) and diabetes mellitus. The identification of a novel homozygous frameshift mutation (c.307_308delTT, p.F103Ter) in SLC29A3 gene, together with the characteristic clinical manifestations of H syndrome, provided accurate diagnosis for this patient., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Background: The term "H syndrome" was coined to denote the major clinical findings, which include hyperpigmentation, hypertrichosis, hearing loss, hepatosplenomegaly, hyperglycaemia, hypogonadism, hallux flexion contractures, and short height., Objective: To report the clinical, endocrinological, histochemical, and genetic findings of three siblings., Methods: Skin and liver biopsies were taken to investigate the histochemical characteristics of hyperpigmented hypertrichotic skin lesions and massive hepatomegaly. The levels of basal serum thyroid hormones, oestradiol, total testosterone, follicle-stimulating hormone, luteinising hormone, and stimulated growth hormone (GH) were measured to investigate the endocrine aspects of the syndrome. Mutation analysis was carried out in all six exons and exon-intron boundaries of SLC29A3 by direct sequencing., Results: Physical examination of the patients revealed common charac-teristic findings of H syndrome. Additional clinical findings were sectorial iris atrophy in the younger sister. Laboratory evaluation revealed microcytic anaemia, markedly increased erythrocyte sedimentation rate and C-reactive protein levels, and humoral immune deficiency in the younger siblings, who presented with recurrent fever and sinopulmonary infection. Two different GH stimulation tests revealed GH deficiency in the younger sister with short stature. Liver and skin biopsies revealed polyclonal lymphohistiocytic and plasma cell infiltration. Sequencing of SLC29A3 in the three siblings revealed a novel homozygous mutation in exon 6, which caused the transition of arginine to tryptophan., Conclusion: This study not only extended the clinical and mutation spectrum of SLC29A3 in H syndrome, but also showed that short children should be assessed according to the guidelines for short stature in children., (© 2019 S. Karger AG, Basel.)

Introduction: H Syndrome is an extremely rare genetic disease, with a multisystemic character and which can be identified in early childhood, offering the opportunity of specific treatment and genetic counselling., Objective: To present a clinical case with "typical" characteristics of H Syndrome., Clinical Case: The case is presented of an 8-year-old male patient who presented with testicular tumours and skin lesions characterised by hyperpigmentation with hypertrichosis, language delay, short stature, and joint deformities. He also presented with bilateral sensorineural hearing loss, anaemia, hypergammaglobulinaemia, and bone disorders. Histopathology studies of the skin and testicular masses reported lymphoplasmacytic infiltration. Sequencing analysis of gene SLC29A3 showed the homozygote mutation c.1087 C>T (p.Arg363Trp; rs387907067)., Conclusions: These findings are consistent with H syndrome, and this is the first reported case in Latin America. The key to the diagnosis is the finding of hyperpigmentation with hypertrichosis., (Copyright © 2016 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: H syndrome is an autosomal recessive genodermatosis with multisystem involvement caused by mutations in SLC29A3., Objective: We sought to investigate the clinical and molecular findings in 79 patients with this disorder., Methods: A total of 79 patients were included, of which 13 are newly reported cases. Because of the phenotypic similarity and molecular overlap with H syndrome, we included 18 patients with allelic disorders. For 31 patients described by others, data were gathered from the medical literature., Results: The most common clinical features (>45% of patients) were hyperpigmentation, phalangeal flexion contractures, hearing loss, and short stature. Insulin-dependent diabetes mellitus and lymphadenopathy mimicking Rosai-Dorfman disease were each found in approximately 20%. Additional systemic features were described in less than 15% of cases. Marked interfamilial and intrafamilial clinical variability exists. Twenty mutations have been identified in SLC29A3, with no genotype-phenotype correlation., Limitations: In the 31 patients described by others, data were collected from the medical literature., Conclusions: H syndrome is a multisystemic disease with clinical variability. Consequently, all SLC29A3-related diseases should be considered a single entity. Recognition of the pleomorphic nature of H syndrome is important for diagnosis of additional patients., (Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

We present a 10-year-old girl with typical clinical features of H syndrome. Complete agenesis of the inferior vena cava was found on echocardiography and radiologic studies. Mutation analysis of the SLC29A3 gene revealed a novel nonsense mutation. This unique case extends the clinical and mutation spectrum associated with H syndrome and underlines the importance of routine cardiac screening in this disorder., (© 2013 Wiley Periodicals, Inc.)

The H syndrome (OMIM 612391) is an autosomal recessive disorder characterized by hyperpigmentation, hypertrichosis, histiocytosis and short stature. It is caused by mutations in the SLC29A3 gene, which encodes for the equilibrative nucleoside transporter 3 protein (ENT3), of still uncertain subcellular localisation. Here we report a new case of H syndrome with the novel mutation c.243delA, which has been concomitantly described by others [A. Bolze, A. Abhyankar, A.V. Grant, B. Patel, R. Yadav, M. Byun, D. Caillez, J.F. Emile, M. Pastor-Anglada, L. Abel, A. Puel, R. Govindarajan, L. de Pontual, J.L. Casanova, A mild form of SLC29A3 disorder: a frameshift deletion leads to the paradoxical translation of an otherwise noncoding mRNA splice variant, PLoS ONE 7 (2012) e29708]. Patient-derived primary skin fibroblasts and B-lymphoblastoid cell lines (B-LCL) were obtained and, although no differences were found in mRNA levels of ENT3, a significant increase in plasma membrane equilibrative transport activity was found in fibroblasts from the patient. Loss of function of key proteins implicated in nucleoside metabolism can lead to mitochondrial DNA (mtDNA) depletion syndromes (MDS). Measurement of respiratory chain complex activity revealed that mitochondrial function was unaltered. Neither fibroblasts nor B-LCL showed mtDNA depletion when compared with controls. Fibroblasts and B-LCL from the patient were not particularly protected when mitochondrial damage was induced using nucleoside-derived drugs susceptible to being transported by ENT3. Analysis of mtDNA amounts in tissues obtained at autopsy proved inconclusive with respect to mitochondrial involvement in the pathogenesis of this syndrome. Overall, the data do not support the inclusion of H syndrome among the MDS and these findings are compatible with its recent inclusion among the lysosomal storage diseases., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The H syndrome (OMIM 612391) is a recently described autosomal recessive disorder characterized by cutaneous hyperpigmentation, hypertrichosis, hepatosplenomegaly, heart anomalies, hearing loss, hypogonadism, short stature (low height), hyperglycaemia/diabetes mellitus, hallux valgus, and fixed flexion contractures of the toe and finger joints.(1,2) Histologically, there is an inflammatory infiltrate consisting mainly of histiocytes, later replaced by fibrosis of the deep dermis and subcutis.(3) In total, 31 patients have been reported in the literature with the clinical phenotype characteristic of this syndrome.(1-7)

The H syndrome is a recently defined autosomal recessive genodermatosis caused by mutations in the nucleoside transporter hENT3. It is characterized by cutaneous changes of progressive sclerosis, hyperpigmentation, and hypertrichosis that follow a specific pattern and are associated with multiple systemic manifestations. A case is presented and a brief review is introduced based on the few related reports.

Type 1 diabetes mellitus is characterized by dysregulation of the immune system leading to inflammation and selective destruction of pancreatic beta cells. Mild to moderate pancreatic exocrine insufficiency is found in patients with type 1 diabetes. Diabetes mellitus may also be part of a syndrome occasionally involving hair and skin abnormalities. We report our observations on two siblings with insulin-dependent diabetes, severe exocrine pancreatic deficiency, pigmented hypertrichotic skin patches with induration and chronic inflammation. The first sibling presented at the age of 9 months with hypertrichosis and hyperpigmentation, particularly on her back and legs and then developed diabetes mellitus at the age of 4 yr. The second sibling presented with exactly the same clinical features but at a later age of 12 yr. Both siblings had severe pancreatic exocrine deficiency with chronic persistent inflammation. Some of the clinical features in these siblings resemble those described by Prendiville et al. although our patients had additional features. The chronic inflammatory response in both siblings is highly suggestive of some form of immune dysregulation. The presence of consanguinity in the parents and similarity of clinical features in the siblings are suggestive of a novel autoimmune disorder, possibly secondary to autosomal recessive inheritance.

The H syndrome is a recently reported autosomal-recessive disorder characterized by cutaneous hyperpigmentation, hypertrichosis, hepatosplenomegaly, heart anomalies, hearing loss, hypogonadism, short stature, hallux valgus, and fixed flexion contractures of the toe joints and the proximal interphalangeal joints. Homozygosity mapping in five consanguineous families resulted in the identification of mutations in the SLC29A3 gene, which encodes the equilibrative nucleoside transporter hENT3. Three mutations were found in 11 families of Arab and Bulgarian origin. The finding of several different mutations in a small geographic region implies that the H syndrome might be rather common. The identification of mutations in the SLC29A3 gene in patients with a mild clinical phenotype suggests that this is a largely underdiagnosed condition and strongly suggests that even oligosymptomatic individuals might have the disorder.

A novel pigmented dermatosis was observed in four unrelated boys, three of whom had insulin-dependent diabetes. Three patients were the offspring of consanguineous parents. All four boys had pigmented hypertrichotic patches or induration on the upper inner thighs, with variable involvement of the genitalia, trunk, and limbs. Two boys had episcleritis and orbital proptosis with similar facies and musculoskeletal abnormalities including clinodactyly, flat feet, and short stature. One child had paraaortic and inguinal lymphadenopathy and three patients had an enlarged liver and spleen. A large, swollen pancreas was observed on ultrasound imaging in one patient with insulin dependent diabetes who also had echocardiographic evidence of pericardial inflammation. Three boys had elevated laboratory markers of inflammation. Biopsy specimens from the skin and orbit showed a chronic inflammatory cell infiltrate composed of polyclonal lymphocytes, histiocytes, and plasma cells; fibrosis was observed in two patients, one of whom had previously received radiation therapy to the orbit. Two boys responded to treatment with subcutaneous interferon-alpha, combined with a short course of oral prednisone in the child without diabetes. We believe these inflammatory pigmented skin lesions represent a unique dermatosis associated with diabetes mellitus and systemic disease. The pathogenesis is unknown. The presence of consanguinity in three of four families, and similar dysmorphic features in two boys, suggest a genetic disorder, possibly with autosomal recessive inheritance.