The Ehlers-Danlos syndromes (EDS) are a clinically and genetically heterogeneous group of heritable connective tissue disorders (HCTDs) characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. Over the past two decades, the Villefranche Nosology, which delineated six subtypes, has been widely used as the standard for clinical diagnosis of EDS. For most of these subtypes, mutations had been identified in collagenencoding genes, or in genes encoding collagen-modifying enzymes. Since its publication in 1998, a whole spectrum of novel EDS subtypes has been described, and mutations have been identified in an array of novel genes. The International EDS Consortium proposes a revised EDS classification, which recognizes 13 subtypes. For each of the subtypes, we propose a set of clinical criteria that are suggestive for the diagnosis. However, in view of the vast genetic heterogeneity and phenotypic variability of the EDS subtypes, and the clinical overlap between EDS subtypes, but also with other HCTDs, the definite diagnosis of all EDS subtypes, except for the hypermobile type, relies on molecular confirmation with identification of (a) causative genetic variant(s). We also revised the clinical criteria for hypermobile EDS in order to allow for a better distinction from other joint hypermobility disorders. To satisfy research needs, we also propose a pathogenetic scheme, that regroups EDS subtypes for which the causative proteins function within the same pathway. We hope that the revised International EDS Classification will serve as a new standard for the diagnosis of EDS and will provide a framework for future research purposes.

Arterial tortuosity syndrome (ATS) is an autosomal recessive\ud disorder characterized by tortuosity, elongation, stenosis and\ud aneurysm formation in the major arteries owing to disruption\ud of elastic fibers in the medial layer of the arterial wall1.\ud Previously, we used homozygosity mapping to map a candidate\ud locus in a 4.1-Mb region on chromosome 20q13.1 (ref. 2).\ud Here, we narrowed the candidate region to 1.2 Mb containing\ud seven genes. Mutations in one of these genes, SLC2A10,\ud encoding the facilitative glucose transporter GLUT10, were\ud identified in six ATS families. GLUT10 deficiency is associated\ud with upregulation of the TGFb pathway in the arterial wall, a\ud finding also observed in Loeys-Dietz syndrome, in which aortic\ud aneurysms associate with arterial tortuosity3. The identification\ud of a glucose transporter gene responsible for altered arterial\ud morphogenesis is notable in light of the previously suggested\ud link between GLUT10 and type 2 diabetes4,5. Our data\ud could provide new insight on the mechanisms causing\ud microangiopathic changes associated with diabetes and\ud suggest that therapeutic compounds intervening with\ud TGFb signaling represent a new treatment strategy

BackgroundClassic Ehlers–Danlos syndrome (cEDS) is a rare autosomal dominant connective tissue disorder that is primarily characterized by skin hyperextensibility, abnormal wound healing/atrophic scars, and joint hypermobility. A recent study demonstrated that more than 90% of patients who satisfy all of these major criteria harbor a type V collagen (COLLV) defect.MethodsThis cohort included 40 patients with cEDS who were clinically diagnosed according to the Villefranche nosology. The flowchart that was adopted for mutation detection consisted of sequencing the COL5A1 gene and, if no mutation was detected, COL5A2 analysis. In the negative patients the presence of large genomic rearrangements in COL5A1 was investigated using MLPA, and positive results were confirmed via SNP-array analysis.ResultsWe report the clinical and molecular characterization of 40 patients from 28 families, consisting of 14 pediatric patients and 26 adults. A family history of cEDS was present in 9 patients. The majority of the patients fulfilled all the major diagnostic criteria for cEDS; atrophic scars were absent in 2 females, skin hyperextensibility was not detected in a male and joint hypermobility was negative in 8 patients (20% of the entire cohort). Wide inter- and intra-familial phenotypic heterogeneity was observed. We identified causal mutations with a detection rate of approximately 93%. In 25/28 probands, COL5A1 or COL5A2 mutations were detected. Twenty-one mutations were in the COL5A1 gene, 18 of which were novel (2 recurrent). Of these, 16 mutations led to nonsense-mediated mRNA decay (NMD) and to COLLV haploinsufficiency and 5 mutations were structural. Two novel COL5A2 splice mutations were detected in patients with the most severe phenotypes. The known p. (Arg312Cys) mutation in the COL1A1 gene was identified in one patient with vascular-like cEDS.ConclusionsOur findings highlight that the three major criteria for cEDS are useful and sufficient for cEDS clinical diagnosis in the large majority of the patients. The borderline patients for whom these criteria fail can be diagnosed when minor signs of connective tissue diseases and family history are present and when genetic testing reveals a defect in COLLV. Our data also confirm that COL5A1 and COL5A2 are the major, if not the only, genes involved in cEDS.

Classical EDS is a heritable disorder of connective tissue. Patients are affected with joint hypermobility, skin hyperextensibilty, and skin fragility leading to atrophic scarring and significant bruising. These clinical features suggest consideration of the diagnosis which then needs to be confirmed, preferably by genetic testing. The most recent criteria for the diagnosis of EDS were devised in Villefranche in 1997 [Beighton et al. (1998); Am J Med Genet 77:31-37].The aims set out in the Villefranche Criteria were: to enable diagnostic uniformity for clinical and research purposes, to understand the natural history of each subtype of EDS, to inform management and genetic counselling, and to identify potential areas of research. The authors recognized that the criteria would need updating, but viewed the Villefranche nosology as a good starting point. Since 1997, there have been major advances in the molecular understanding of classical EDS. Previous question marks over genetic heterogeneity have been largely surpassed by evidence that abnormalities in type V collagen are the cause. Advances in molecular testing have made it possible to identify the causative mutation in the majority of patients. This has aided the further clarification of this diagnosis. The aim of this literature review is to summarize the current knowledge and highlight areas for future research.

We report on an autosomal-recessive variant of Ehlers-Danlos syndrome (EDS) characterized by severe muscle hypotonia at birth, progressive scoliosis, joint hypermobility, hyperelastic skin, myopathy, sensorineural hearing impairment, and normal pyridinoline excretion in urine. Clinically, the disorder shares many features with the kyphoscoliotic type of EDS (EDS VIA) and Ullrich congenital muscular dystrophy. Linkage analysis in a large Tyrolean kindred identified a homozygous frameshift mutation in FKBP14 in two affected individuals. Based on the cardinal clinical characteristics of the disorder, four additional individuals originating from different European countries were identified who carried either homozygous or compound heterozygous mutations in FKBP14. FKBP14 belongs to the family of FK506-binding peptidyl-prolyl cis-trans isomerases (PPIases). ER-resident FKBPs have been suggested to act as folding catalysts by accelerating cis-trans isomerization of peptidyl-prolyl bonds and to act occasionally also as chaperones. We demonstrate that FKBP14 is localized in the endoplasmic reticulum (ER) and that deficiency of FKBP14 leads to enlarged ER cisterns in dermal fibroblasts in vivo. Furthermore, indirect immunofluorescence of FKBP14-deficient fibroblasts indicated an altered assembly of the extracellular matrix in vitro. These findings suggest that a disturbance of protein folding in the ER affecting one or more components of the extracellular matrix might cause the generalized connective tissue involvement in this disorder. FKBP14 mutation analysis should be considered in all individuals with apparent kyphoscoliotic type of EDS and normal urinary pyridinoline excretion, in particular in conjunction with sensorineural hearing impairment.