Vascular Ehlers-Danlos syndrome (vEDS) is a rare and severe autosomal dominant disorder caused by variants at the COL3A1 gene. Clinical characteristics and course of disease of 215 molecularly proven patients (146 index cases and 69 relatives) were analysed. We found 126 distincts variants that were divided into five groups: (1) Glycine substitutions (n = 71), (2) splice-site and in-frame insertions-deletions (n = 36), (3) variants leading to haplo-insufficiency (n = 7), (4) non-glycine missense variants within the triple helix (n = 4 variants), and (5) non-glycine missense variants or in-frame insertions-deletions, in the N-or C-terminal part of the protein (n = 8). Overall, our cohort confirmed the severity of the disease with a median age at first complication of 29 years (IQR 22-39), the most frequent being arterial (48%) and digestive (24%) ruptures. Groups 2 and 1 were significantly more severe than groups 3-5, with extreme median ages at first major complication of 23-47 years. Patients of groups 3-5 had a less typical phenotype and remarkably absence of digestive events. The distribution of glycine-replacing amino acids was strongly biased towards more destabilizing residues of the collagen assembly. Thus the natural course of vEDS and the clinical phenotype of patients are influenced by the type of COL3A1 variant. This study also confirms that patients with variants located in the C-and N-termini or leading to haplo-insufficiency have milder course of the disease and less prevalent diagnostic criteria. These findings may help refine diagnostic strategy, genetic counselling and clinical care.

Chuvash polycythemia is an autosomal recessive form of erythrocytosis associated with a homozygous p.Arg200Trp mutation in the von Hippel-Lindau () gene. Since this discovery, additional mutations have been identified in patients with congenital erythrocytosis, in a homozygous or compound-heterozygous state. is a major tumor suppressor gene, mutations in which were first described in patients presenting with VHL disease, which is characterized by the development of highly vascularized tumors. Here, we identify a new cryptic exon (termed E1') deep in intron 1 that is naturally expressed in many tissues. More importantly, we identify mutations in E1' in 7 families with erythrocytosis (1 homozygous case and 6 compound-heterozygous cases with a mutation in E1' in addition to a mutation in coding sequences) and in 1 large family with typical VHL disease but without any alteration in the other exons. In this study, we show that the mutations induced a dysregulation of splicing with excessive retention of E1' and were associated with a downregulation of VHL protein expression. In addition, we demonstrate a pathogenic role for synonymous mutations in exon 2 that altered splicing through E2-skipping in 5 families with erythrocytosis or VHL disease. In all the studied cases, the mutations differentially affected splicing, correlating with phenotype severity. This study demonstrates that cryptic exon retention and exon skipping are new alterations and reveals a novel complex splicing regulation of the gene. These findings open new avenues for diagnosis and research regarding the VHL-related hypoxia-signaling pathway.

We propose an updated PS including renal and neurological features and adaptation of follow-up according to the genetic and ethnic status of PXE-affected patients.Genet Med advance online publication 19 January 2017.

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This study demonstrates that the risk of developing PPGL for a subject carrying a germline SDHD mutation on the maternal allele remains a rare scenario but does exist. Our data suggest an adjustment of current genetic counselling and clinical care recommendations for at-risk subjects. A targeted familial genetic test should be proposed from the age of 18 years to every subject having a mother carrying a germline SDHD mutation and a first medical workup, including imaging, should be recommended to SDHD-positive mutation carriers.

Background: Vascular Ehlers-Danlos syndrome is a rare inherited connective tissue disease secondary to mutations within the COL3A1 gene. The diagnosis of vascular Ehlers-Danlos syndrome is challenging, and patient selection for genetic testing relies on diagnostic criteria, which have never been evaluated. Methods: All patients seen at a dedicated tertiary referral center for a suspicion of vascular Ehlers-Danlos syndrome between January 2001 and March 2016 were retrospectively included in a diagnostic accuracy study. Major and minor diagnostic criteria of the Villefranche classification were tested for sensitivity, specificity, positive and negative predictive values, according to results of genetic testing. Results: N=519 patients were eligible for analysis dividing into n=384 probands and n=135 relatives. A pathogenic COL3A1 variant was identified in n=165 (31.8%) patients. The Villefranche criteria were met for n=248 patients with a sensitivity of 79% (95% CI, 0.72–0.85) and a negative predictive value of 87% (95% CI, 0.83–0.91). Diagnostic accuracy was highest for symptomatic probands (sensitivity 92%; negative predictive value 95%) with limited specificity (60%). Probands ≤25 years had the worst diagnostic performance. The revised diagnostic Criteria (2017) were less accurate than the Villefranche classification (overall diagnostic odds-ratio, 4.17 versus 7.8; probands diagnostic odds-ratio, 4.04 versus 18.1; and probands ≤25 years diagnostic odds-ratio, 2.36 versus 5.1) mainly due to a lack of sensitivity. Conclusions: The Villefranche criteria provide accurate detection of symptomatic probands in specialized practice but have limited specificity. The revised diagnostic criteria for vascular Ehlers-Danlos syndrome have increased specificity, but its overall performance is poorer. The early clinical diagnosis of probands without family history is not addressed by both diagnostic classifications.

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