Identification of a p.Ser81Arg encoding mutation in SLC2A10 gene of arterial tortuosity syndrome patients from 10 Qatari families

Arterial Tortuosity Syndrome in a Newborn: A Case Report With Literature Review

Arterial tortuosity syndrome (ATS; OMIM #208050) is a sporadic, autosomal, recessively inherited genetic disorder. ATS primarily causes the tortuosity and elongation of large and medium-sized arteries; however, other skeletal manifestations include dysmorphic features, such as hyperextensible skin, hypermobile joints, and congenital contractures. The present article reports the case of a female neonate, who, at birth, exhibited abnormal facial features, hypermobility of joints, and abnormal physical appearance. The patient was diagnosed with ATS during the first week of life, based on computed tomographic scans. In addition, angiographic results demonstrated elongation and tortuosity of the aorta, which were further supported using the results of genetic analysis. Mutation analysis of the solute carrier family 2 member 10 (SLC2A10) genes (Entrez Gene: 81031) detected a homozygous pathogenic c.243C>G (p. Ser81Arg) variant (dbSNP: rs80358230) in this patient, which supports the clinical diagnosis of ATS. Following the initial diagnosis, further investigations into the family history were carried out, and the results demonstrated that the patient's paternal grandmother and paternal aunt were also positive for ATS. The patient was subsequently referred to a tertiary care center for genetic counseling and further follow-up. Notably, carrier testing for at-risk relatives is recommended to identify family members that may be affected by this condition.

Investigation of Genetic Causes in Patients with Congenital Heart Disease in Qatar: Findings from the Sidra Cardiac Registry

Congenital heart disease (CHD) is one of the most common forms of birth defects worldwide, with a prevalence of 1–2% in newborns. CHD is a multifactorial disease partially caused by genetic defects, including chromosomal abnormalities and single gene mutations. Here, we describe the Sidra Cardiac Registry, which includes 52 families and a total of 178 individuals, and investigate the genetic etiology of CHD in Qatar. We reviewed the results of genetic tests conducted in patients as part of their clinical evaluation, including chromosomal testing. We also performed whole exome sequencing (WES) to identify potential causative variants. Sixteen patients with CHD had chromosomal abnormalities that explained their complex CHD phenotype, including six patients with trisomy 21. Moreover, using exome analysis, we identified potential CHD variants in 24 patients, revealing 65 potential variants in 56 genes. Four variants were classified as pathogenic/likely pathogenic based on the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) classification; these variants were detected in four patients. This study sheds light on several potential genetic variants contributing to the development of CHD. Additional functional studies are needed to better understand the role of the identified variants in the pathogenesis of CHD.

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.

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.

Clinical genetics and genomic medicine in Qatar

Clinical genetics and genomic medicine in Qatar.

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.

Arterial Tortuosity Syndrome: An Approach through Imaging Perspective

This pictorial illustration demonstrates various aspects of arterial tortuosity syndrome (ATS) obtained predominantly from a multiple detector computed tomography (MDCT) examination of a patient. In addition, a comprehensive review of typical multi-modality imaging observations in patients with ATS is presented along with a description of a few imaging signs. Non-invasively obtained, conclusive information is required in patients with ATS in view of the fragile vascular structures involved. An amazing wealth of information can be obtained by reviewing the volumetric data sets of MDCT examination. In the context of incomplete clinical information or remote reading of radiographic examination with inadequate clinical details, ability to “image data mine” the hidden, unexplored information may be vastly useful. The role of MDCT as a single modality of evaluation in ATS is highlighted.

New molecular genetic tests in the diagnosis of heart disease

With the increasing use of next-generation sequencing applications, there has been an increase in identification of genetic causes of cardiac disease. This technology has also enabled the transition of these genes into the clinical setting and the rapid growth of large gene tests for the diagnosis of heart disorders. The ability to combine tests to include similar, but distinct, diseases has shown that many genes can be responsible for a wide variety of both syndromic and nonsyndromic disorders. This article discusses the current state of molecular genetic diagnosis for cardiac disorders, focusing on diseases with mendelian inheritance.

Exome sequencing identifies potential risk variants for Mendelian disorders at high prevalence in Qatar

Exome sequencing of families of related individuals has been highly successful in identifying genetic polymorphisms responsible for Mendelian disorders. Here, we demonstrate the value of the reverse approach, where we use exome sequencing of a sample of unrelated individuals to analyze allele frequencies of known causal mutations for Mendelian diseases. We sequenced the exomes of 100 individuals representing the three major genetic subgroups of the Qatari population (Q1 Bedouin, Q2 Persian-South Asian, Q3 African) and identified 37 variants in 33 genes with effects on 36 clinically significant Mendelian diseases. These include variants not present in 1000 Genomes and variants at high frequency when compared with 1000 Genomes populations. Several of these Mendelian variants were only segregating in one Qatari subpopulation, where the observed subpopulation specificity trends were confirmed in an independent population of 386 Qataris. Premarital genetic screening in Qatar tests for only four out of the 37, such that this study provides a set of Mendelian disease variants with potential impact on the epidemiological profile of the population that could be incorporated into the testing program if further experimental and clinical characterization confirms high penetrance.

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.

Hereditary disorders of connective tissue: a guide to the emerging differential diagnosis

PURPOSE

To create a practical desk reference for clinicians focused on the differential diagnosis of individuals presenting with features that suggest an inherited disorder of connective tissue.

METHODS

We searched the medical literature for distinct clinical entities that shared clinical features with Marfan syndrome and other classical inherited disorders of connective tissue.

RESULTS

Thirty-six distinct heritable disorders of connective tissue were identified that have overlapping features. These disorders were organized into two matrices according to clinical characteristics and according to causative genes.

CONCLUSIONS

A broad differential diagnosis is emerging for individuals presenting with features suggestive of altered connective tissue. Recent advances in molecular genetics have aided in the delineation of these disorders.

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.

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

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive disorder in which patients display tortuosity of arteries in addition to hyperextensible skin, joint laxity, and other connective tissue features. This syndrome is caused by mutations in the SLC2A10 gene. In this article we describe an ATS girl of Kurdish origin who, in addition to arterial tortuosity and connective tissue features, displays stomach displacement within the thorax and bilateral hip dislocation. Clinical details of this patient have been reported previously. Sequencing of the SLC2A10 gene identified a novel homozygous non-sense c.756C>A mutation in this patient's DNA. This mutation in the SLC2A10 gene replaces a cysteine encoding codon with a stop signal. This is believed to cause a premature truncation of GLUT10 protein in this patient. We conclude that patients of Kurdish origin who display arterial tortuosity associated with skin hyperextensibility, joint hypermobility, and characteristic facial features may carry mutations in the SLC2A10 gene.