A novel non-sense mutation in the SLC2A10 gene of an arterial tortuosity syndrome patient of Kurdish origin

Progressive Keratoconus in a Patient With Severe Pectus Excavatum and a Cartilage Oligomeric Matrix Protein Gene Mutation: A Case Report

INTRODUCTION

Keratoconus is a progressive ocular disorder associated with numerous systemic diseases, many of which affect the musculoskeletal system. Although the etiology and pathophysiology of the disorder remain elusive, recent studies suggest a significant role of genetic predisposition in the pathogenesis of keratoconus. This case report aims to elucidate a potential genetic association in a patient presenting with keratoconus, severe pectus excavatum, generalized muscular weakness, and skeletal deformities.

CASE DESCRIPTION

A 31-year-old Iranian man presented with progressively diminishing vision in both eyes over the years, eventually diagnosed with keratoconus. The patient's history and further examination indicated generalized muscular weakness, skeletal deformities, and severe pectus excavatum with cardiac and large vessel displacement. Whole-exome sequencing identified two heterozygous gene variants: one in the Cartilage Oligomeric Matrix Protein (COMP) gene and another in the Regulating Synaptic Membrane Exocytosis 1 gene. The patient's systemic and ocular symptoms, combined with the gene variants identified, suggested a connective tissue systemic disorder, potentially within the clinical spectrum of COMPopathies.

CONCLUSION

This is the first documented case of bilateral progressive keratoconus associated with severe pectus excavatum, generalized musculoskeletal dystrophy, and a COMP gene mutation. It highlights the necessity of continued search into the pathogenic genes of keratoconus, particularly in cases with coexisting systemic manifestations, to further our understanding of the etiology and pathogenesis of this complex disease.

Metabolic Cardiomyopathies and Cardiac Defects in Inherited Disorders of Carbohydrate Metabolism: A Systematic Review

Heart failure (HF) is a progressive chronic disease that remains a primary cause of death worldwide, affecting over 64 million patients. HF can be caused by cardiomyopathies and congenital cardiac defects with monogenic etiology. The number of genes and monogenic disorders linked to development of cardiac defects is constantly growing and includes inherited metabolic disorders (IMDs). Several IMDs affecting various metabolic pathways have been reported presenting cardiomyopathies and cardiac defects. Considering the pivotal role of sugar metabolism in cardiac tissue, including energy production, nucleic acid synthesis and glycosylation, it is not surprising that an increasing number of IMDs linked to carbohydrate metabolism are described with cardiac manifestations. In this systematic review, we offer a comprehensive overview of IMDs linked to carbohydrate metabolism presenting that present with cardiomyopathies, arrhythmogenic disorders and/or structural cardiac defects. We identified 58 IMDs presenting with cardiac complications: 3 defects of sugar/sugar-linked transporters (GLUT3, GLUT10, THTR1); 2 disorders of the pentose phosphate pathway (G6PDH, TALDO); 9 diseases of glycogen metabolism (GAA, GBE1, GDE, GYG1, GYS1, LAMP2, RBCK1, PRKAG2, G6PT1); 29 congenital disorders of glycosylation (ALG3, ALG6, ALG9, ALG12, ATP6V1A, ATP6V1E1, B3GALTL, B3GAT3, COG1, COG7, DOLK, DPM3, FKRP, FKTN, GMPPB, MPDU1, NPL, PGM1, PIGA, PIGL, PIGN, PIGO, PIGT, PIGV, PMM2, POMT1, POMT2, SRD5A3, XYLT2); 15 carbohydrate-linked lysosomal storage diseases (CTSA, GBA1, GLA, GLB1, HEXB, IDUA, IDS, SGSH, NAGLU, HGSNAT, GNS, GALNS, ARSB, GUSB, ARSK). With this systematic review we aim to raise awareness about the cardiac presentations in carbohydrate-linked IMDs and draw attention to carbohydrate-linked pathogenic mechanisms that may underlie cardiac complications.

Ultrastructure abnormalities of collagen and elastin in Arab patients with arterial tortuosity syndrome

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive disease characterized by elongation and tortuosity of the large and medium sized arteries. ATS patients display features that are also found in Ehlers-Danlos syndromes (EDS) patients. ATS is caused by pathogenic mutations in the SLC2A10 gene, which encodes for the glucose transporter, GLUT10. The study aimed at examining the ultrastructure of skin for abnormalities that can explain the loose skin and arterial phenotypes of Arab patients with the p.S81R mutation in SLC2A10. Forty eight patients with SLC2A10 mutation were recruited for this study. Skin biopsy specimens from 3 children with ATS and a healthy child were examined by electron microscopy to determine the ultrastructure of collagen and elastin. Histopathologic staining of sections from tissue biopsy specimens were also performed. In the skin from ATS patients, large spaces are discovered among collagen fibrils suggesting disorganization of the collagen structures. Furthermore, elastin fiber contents and their thickness are reduced in the skin. In small muscular arteries in the skin from ATS patients, discontinued internal elastic lamina, lack of myofilaments, and disorganized medial smooth muscle cells with vacuolated cytoplasm are present. The disorganization of collagen fibrils and reduced elastin contents in the skin may explain the loose skin phenotype of ATS patients similar to the EDS patients. The lack of elastin in small muscular arteries may have contributed to the development of arterial tortuosity in these patients. This article is protected by copyright. All rights reserved.

Two fetuses in one family of arterial tortuosity syndrome: prenatal ultrasound diagnosis

Background

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive connective tissue disorder chiefly characterized by elongated and tortuosity of the large and medium sized arteries and anomalies of the vascular elastic fibers. Here we reported cases of brother about ATS from the same family on the prenatal ultrasound diagnosis. Reports of this case are rare in antenatally and we draw the vessel simulated diagram to display visually.

Case presentation

Prenatal ultrasound scanning at 29 weeks of gestation of the first fetus showed obvious tortuous and elongated of the aortic arch, ductus arteriosus, left and right pulmonary arteries, carotid and subclavian arteries. Three months after delivery, Contrast-enhanced computed tomography images (CTA) were performed to clearly display vascular abnormalities consistent with prenatal diagnosis of ultrasound. Whole exome sequencing (WES) was performed eight months after birth, two heterozygous variants of SLC2A10 gene was detected in newborn and their father and mother, respectively. Prenatal ultrasound scan at 22 weeks of gestation of the second fetus showed similar cardiovascular imaging. After birth the siblings have facial characteristic features gradually as aging. No surgical intervention was performed in the siblings follow up 19 months.

Conclusions

The key points of prenatal ultrasound diagnosis of ATS are the elongation and tortuosity of the large and medium sized arteries. Genetic counseling is the process of providing individuals and families with information on the nature, inheritance, and implications of genetic disorders to help them make informed medical and personal decisions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03960-w.

Glucose Transport and Transporters in the Endomembranes

Glucose is a basic nutrient in most of the creatures; its transport through biological membranes is an absolute requirement of life. This role is fulfilled by glucose transporters, mediating the transport of glucose by facilitated diffusion or by secondary active transport. GLUT (glucose transporter) or SLC2A (Solute carrier 2A) families represent the main glucose transporters in mammalian cells, originally described as plasma membrane transporters. Glucose transport through intracellular membranes has not been elucidated yet; however, glucose is formed in the lumen of various organelles. The glucose-6-phosphatase system catalyzing the last common step of gluconeogenesis and glycogenolysis generates glucose within the lumen of the endoplasmic reticulum. Posttranslational processing of the oligosaccharide moiety of glycoproteins also results in intraluminal glucose formation in the endoplasmic reticulum (ER) and Golgi. Autophagic degradation of polysaccharides, glycoproteins, and glycolipids leads to glucose accumulation in lysosomes. Despite the obvious necessity, the mechanism of glucose transport and the molecular nature of mediating proteins in the endomembranes have been hardly elucidated for the last few years. However, recent studies revealed the intracellular localization and functional features of some glucose transporters; the aim of the present paper was to summarize the collected knowledge.

Arterial Tortuosity Syndrome: homozygosity for two novel and one recurrent SLC2A10 missense mutations in three families with severe cardiopulmonary complications in infancy and a literature review

Background

Arterial Tortuosity Syndrome (ATS) is a very rare autosomal recessive connective tissue disorder (CTD) characterized by tortuosity and elongation of the large- and medium-sized arteries and a propensity for aneurysm formation and vascular dissection. During infancy, children frequently present the involvement of the pulmonary arteries (elongation, tortuosity, stenosis) with dyspnea and cyanosis. Other CTD signs of ATS are dysmorphisms, abdominal hernias, joint hypermobility, skeletal abnormalities, and keratoconus. ATS is typically described as a severe disease with high rate of mortality due to major cardiovascular malformations. ATS is caused by mutations in the SLC2A10 gene, which encodes the facilitative glucose transporter 10 (GLUT10). Approximately 100 ATS patients have been described, and 21 causal mutations have been identified in the SLC2A10 gene.

Case presentation

We describe the clinical findings and molecular characterization of three new ATS families, which provide insight into the clinical phenotype of the disorder; furthermore, we expand the allelic repertoire of SLC2A10 by identifying two novel mutations. We also review the ATS patients characterized by our group and compare their clinical findings with previous data.

Conclusions

Our data confirm that the cardiovascular prognosis in ATS is less severe than previously reported and that the first years of life are the most critical for possible life-threatening events. Molecular diagnosis is mandatory to distinguish ATS from other CTDs and to define targeted clinical follow-up and timely cardiovascular surgical or interventional treatment, when needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-014-0122-5) contains supplementary material, which is available to authorized users.

Artery tortuosity syndrome exhibiting early-onset emphysema with novel compound heterozygous SLC2A10 mutations

We report on a 2-year-old Japanese boy with early-onset pulmonary emphysema, exhibiting dysmorphic face, loose skin, and inguinal and Morgagni hernias. He was admitted to our hospital owing to refractory respiratory infection. On the basis of his clinical features, we investigated the SLC2A10 gene and identified novel compound heterozygous mutations of c.417T > A and c.692G > A, leading to the diagnosis of artery tortuosity syndrome (ATS). This syndrome is an extremely rare autosomal recessive disorder characterized by tortuosity and elongation of the large and medium-sized arteries, hyperextensible skin, and diverse hernias, mostly reported from Europe and Middle Eastern countries, but not from Asia. Although chronic obstructive pulmonary disease, namely, emphysema, has not been well documented in ATS, it may be likely because TGF-beta up-regulation is known to be evoked by SLC2A10 mutations, resulting in reconstruction of pulmonary endothelial cells and emphysema. This is the first report of ATS associated with early-onset pulmonary emphysema, suggesting that patients with ATS may also require close attention for chronic obstructive pulmonary disease.

Adult presentation of arterial tortuosity syndrome in a 51-year-old woman with a novel homozygous c.1411+1G>A mutation in the SLC2A10 gene

Arterial tortuosity syndrome (ATS) is an autosomal recessive connective tissue disorder, mainly characterized by tortuosity and elongation of the large- and medium-sized arteries with predisposition to stenoses and aneurysms. ATS is caused by mutations in the SLC2A10 gene, encoding for the facilitative glucose transporter 10 (GLUT10) and is described typically in pediatric patients. We report on a 51-year-old woman, originally ascertained because of unexplained widespread chronic pain and positive family history of aortic malformation. The main findings included aged appearance, congenital joint hypermobility, joint instability complications, chronic fatigue syndrome, progressive painful joint stiffness, abdominal hernias, pelvic prolapses, multiple cardiac valve prolapses, varicose veins, easy bruising, and gingival recession. Vascular imaging revealed kinking and anomalous origin of the aortic arch branches, marked tortuosity of the aorta, pulmonary and most middle arteries, and a small aneurysm of the splenic artery. SLC2A10 analysis disclosed homozygosity for the novel c.1411+1G>A splice mutation, leading to a 41 amino acids GLUT10 internal deletion. Expression study by immunofluorescence using healthy control cells showed lack of membrane internalization of GLUT10 in patient's skin fibroblasts. This report describes the first splice-site SLC2A10 mutation and increases to 19 the repertoire of known mutations in this gene. Comparison with the few previously published adult patients with ATS contributes to the natural history of this condition, which is probably under diagnosed within the expanding family of inherited connective tissue disorders.

SLC2A10 genetic polymorphism predicts development of peripheral arterial disease in patients with type 2 diabetes. SLC2A10 and PAD in type 2 diabetes

Background

Recent data indicate that loss-of-function mutation in the gene encoding the facilitative glucose transporter GLUT10 (SLC2A10) causes arterial tortuosity syndrome via upregulation of the TGF-β pathway in the arterial wall, a mechanism possibly causing vascular changes in diabetes.

Methods

We genotyped 10 single nucleotide polymorphisms and one microsatellite spanning 34 kb across the SLC2A10 gene in a prospective cohort of 372 diabetic patients. Their association with the development of peripheral arterial disease (PAD) in type 2 diabetic patients was analyzed.

Results

At baseline, several common SNPs of SLC2A10 gene were associated with PAD in type 2 diabetic patients. A common haplotype was associated with higher risk of PAD in type 2 diabetic patients (haplotype frequency: 6.3%, P = 0.03; odds ratio [OR]: 14.5; 95% confidence interval [CI]: 1.3- 160.7) at baseline. Over an average follow-up period of 5.7 years, carriers with the risk-conferring haplotype were more likely to develop PAD (P = 0.007; hazard ratio: 6.78; 95% CI: 1.66- 27.6) than were non-carriers. These associations remained significant after adjustment for other risk factors of PAD.

Conclusion

Our data demonstrate that genetic polymorphism of the SLC2A10 gene is an independent risk factor for PAD in type 2 diabetes.

Arterial tortuosity syndrome in two Italian paediatric patients

Background

Arterial tortuosity syndrome (ATS) (OMIM #208050) is a rare autosomal recessive connective tissue disorder characterized by tortuosity and elongation of the large and medium-sized arteries, propensity to aneurysms formation, vascular dissection, and pulmonary arteries stenosis. ATS is caused by mutations in SLC2A10 gene, encoding for the facilitative glucose transporter 10 (GLUT10). So far, 17 SLC2A10 mutations have been reported in 32 families, two of which were Italian with a total of five patients. Here we present the clinical and molecular characterization of two novel Italian paediatric ATS patients.

Methods

The exons and intronic flanking regions of SLC2A10 gene were amplified and direct sequencing was performed.

Results

In both patients, the involvement of major- and medium-sized arteries was characteristic; the nonvascular connective tissue manifestations were mild and not pathognomic of the disorder. Both patients, born from non-consanguineous parents, were heterozygous for two different SLC2A10 mutations, three of which were recurrent and one was novel (p.Arg231Trp). This mutation is localized at the endofacial loop between the transmembrane domains 6 and 7 of GLUT10.

Conclusion

Two novel ATS patients were characterized at clinical and molecular level. Overall, four ATS unrelated families are known in Italy so far. Though ATS clinical delineation improved in the last years, further works in the comprehension of disease presentation and complications onset, particularly in paediatric age, and on ATS molecular basis are needed to add new insights for diagnosis and prevention strategies for related complications.