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In a family with pulmonary arterial hypertension, whole-exome sequencing led to identification of a mutation in the potassium-channel gene KCNK3 . Additional mutations resulting in loss of function of the channel were found in other families and in patients with idiopathic disease. Pulmonary arterial hypertension is a rare disease that is characterized by increased pulmonary-artery pressure in the absence of common causes of pulmonary hypertension, such as chronic heart, lung, or thromboembolic disease. 1 Before the advent of novel therapies, patients with idiopathic or familial pulmonary arterial hypertension had an estimated median survival of 2.8 years, with 1-year, 3-year, and 5-year survival rates of 68%, 48%, and 34%, respectively. 2 However, despite progress in treatment, pulmonary arterial hypertension remains a progressive, fatal disease. The clinical presentation can be nonspecific, and patients often receive a diagnosis late in their clinical course. The cause of pulmonary . . .

Florent Soubrier and colleagues identify biallelic mutations in EIF2AK4 as a major cause of pulmonary veno-occlusive disease, a rare form of pulmonary hypertension. EIF2AK4 encodes a serine-threonine kinase, and the disease-causing mutations are predicted to result in loss of protein function. Pulmonary veno-occlusive disease (PVOD) is a rare and devastating cause of pulmonary hypertension that is characterized histologically by widespread fibrous intimal proliferation of septal veins and preseptal venules and is frequently associated with pulmonary capillary dilatation and proliferation 1 , 2 . PVOD is categorized into a separate pulmonary arterial hypertension–related group in the current classification of pulmonary hypertension 3 . PVOD presents either sporadically or as familial cases with a seemingly recessive mode of transmission 4 . Using whole-exome sequencing, we detected recessive mutations in EIF2AK4 (also called GCN2 ) that cosegregated with PVOD in all 13 families studied. We also found biallelic EIF2AK4 mutations in 5 of 20 histologically confirmed sporadic cases of PVOD. All mutations, either in a homozygous or compound-heterozygous state, disrupted the function of the gene. These findings point to EIF2AK4 as the major gene that is linked to PVOD development and contribute toward an understanding of the complex genetic architecture of pulmonary hypertension.

Background and Objective Superficial vascular anomalies are complex disorders characterized by abnormal vascular growth. Next-generation sequencing has recently identified somatic genetic alterations associated with these malformations, offering new insights for targeted treatments. However, tissue biopsies for genetic testing can be invasive and difficult to obtain, especially in arteriovenous malformations (AVM) with hemorrhagic risks. À liquid biopsy, a non-invasive approach, offers a promising solution by detecting genetic mutations in cell-free DNA. This pilot study aimed to evaluate the feasibility of using a liquid biopsy for the genetic analysis of patients with superficial vascular anomalies through cell-free DNA sampling. Additionally, it explored whether specific sampling sites, such as the afferent artery, nidus, and efferent vein, could enhance the sensitivity of detecting pathogenic variants in patients with AVM. Methods A total of 88 patients were enrolled, including 55 with AVM and 33 with lymphatic malformations. For patients with AVM, cell-free DNA samples were collected from peripheral blood, efferent veins, afferent arteries, and the AVM nidus. In patients with lymphatic malformations, cystic lymphatic fluid was collected by a direct puncture during diagnostic procedures. A molecular analysis was performed using a targeted gene panel relevant to somatic alterations in solid tumors. Pathogenic variants were validated by digital polymerase chain reaction for patients with lymphatic malformations. Results Pathogenic variants were identified in 23.6% of patients with AVM, predominantly in MAP2K and KRAS genes, with higher sensitivity near the AVM nidus. In addition, pathogenic variants were identified in 27.3% of patients with lymphatic malformations, all involving the PIK3CA gene. Despite the lower sensitivity of a cell-free DNA analysis compared with a tissue biopsy, especially in patients with AVM, the detection rate suggests the utility for a cell-free DNA analysis, particularly when a tissue biopsy is not feasible. Conclusions This study confirms the feasibility of using a cell-free DNA liquid biopsy for genotyping patients with superficial vascular anomalies, although a tissue biopsy remains the gold standard for comprehensive genetic profiling because of its higher sensitivity. A liquid biopsy offers a non-invasive option for molecular analysis that is useful as a preliminary or alternative approach when direct tissue sampling is not possible. Importantly, the sensitivity of cell-free DNA sampling in AVM appeared highest when obtained close to the nidus, indicating an optimal sampling location for future studies. Further research is needed to improve detection sensitivity, especially for samples taken near the nidus, to validate and strengthen these findings. Although our study focused on superficial/extra-cranial AVM, further research should assess the applicability of this approach to cerebral AVM, where a tissue biopsy is particularly risky.

Background Previous studies indicate that patients with pulmonary arterial hypertension (PAH) carrying a mutation in the bone morphogenetic protein receptor type 2 ( BMPR2 ) gene, develop the disease 10 years earlier than non-carriers, and have a more severe hemodynamic compromise at diagnosis. A recent report has suggested that this may only be the case for females and that patients with missense mutations in BMPR2 gene have more severe disease than patients with truncating mutations. Methods We reviewed data from all patients with PAH considered as idiopathic and patients with a family history of PAH, who underwent genetic counselling in the French PAH network between January, 1 st 2004 and April, 1 st 2010. We compared clinical, functional, and hemodynamic characteristics between carriers and non-carriers of a BMPR2 mutation, according to gender or BMPR2 mutation type. Results PAH patients carrying a BMPR2 mutation (n = 115) were significantly younger at diagnosis than non-carriers (n = 267) (35.8 ± 15.4 and 47.5 ± 16.2 respectively, p < 0.0001). The presence of a BMPR2 mutation was associated with a younger age at diagnosis in females (36.4 ± 14.9 in BMPR2 mutation carriers and 47.4 ± 15.8 in non-carriers, p < 0.0001), and males (34.6 ± 16.8 in BMPR2 mutation carriers and 47.8 ± 17.1 in non-carriers, p < 0.0001). BMPR2 mutation carriers had a more severe hemodynamic compromise at diagnosis, but this was not influenced by gender. No differences in survival and time to death or lung transplantation were found in male and female PAH patients carrying a BMPR2 mutation. No differences were observed in clinical outcomes according to the type of BMPR2 mutations (missense, truncating, large rearrangement or splice defect). Conclusion When compared to non-carriers, BMPR2 mutation carriers from the French PAH network are younger at diagnosis and present with a more severe hemodynamic compromise, irrespective of gender. Moreover, BMPR2 mutation type had no influence on clinical phenotypes in our patient population.

Splenic artery aneurysm (SAA) is a rare but potentially fatal condition. Rupture results in 25% mortality up to 75% in pregnant women with 95% fetal mortality. Brief reports suggest an increased risk of developing SAA in patients with HHT. We analyzed enhanced multidetector CT data in 186 HHT patients matched (gender and ± 5 year old) with 186 controls. We screened for SAA and recorded diameter of splenic and hepatic arteries and hepatic, pancreatic and splenic parenchymal involvements. We determined by univariate and multivariate analysis, the relationship with age, sex, genetic status, cardiovascular risk factors (CVRF) and visceral involvement. SAA concerned 24.7% of HHT patients and 5.4% of controls, p<0.001. Factors associated with increased risk of SAA in HHT were female gender (p = 0.04, OR = 2.12, IC 95% = 1.03-4.50), age (p = 0.0003, OR = 1.04, 95% CI = 1.02-1.06) and pancreatic parenchymal involvement (p = 0.04, OR = 2.13, 95% CI = 1.01-4.49), but not type of mutation, hepatic or splenic parenchymal involvements, splenic size or splenic artery diameter or CVRF. We found a 4.57 higher rate of SAA in HHT patients without evidence of splenic high output related disease or increased CVRF. These results suggest the presence of a vascular intrinsic involvement. It should lead to screening all HHT patients for SAA. The vasculopathy hypothesis could require a change in management as screening of all systemic arteries and even the aorta and to further research in the field.

Some patients happen to have a colorectal cancer with microsatellite instability (MSI), but without any alteration in Mismatch Repair (MMR) system (germline mutation/promoter methylation). We aimed to identify the mechanism of inactivation of MMR genes in those cases. We studied 18 patients with MSI CCR and loss of expression of a MMR protein. DNA was extracted from tumoral and normal colonic material. We studied the 3 main MMR genes in tumors, by sequencing and large rearrangement analysis, and looked for mosaicism. Seven patients lost expression of MLH1 , we found 1 mutation in the tumor for 3 patients and 2 mutations in one. Eight patients lost expression of MSH2 : we found 1 mutation in 2 patients and 2 mutations in four. In the 5 cases with 2 hits, MSI was due to double somatic hits (n = 3), mosaicism (n = 1) and missed germline mutation (n = 1). Mosaicism was confirmed by HRM analysis, and by finding a germline mutation in one patient’s son. We could explain MSI in the tumors of 5 patients (27.8 %). Their follow up and family’s surveillance could be adjusted, as the sporadic cases don’t require intensive surveillance. We describe the first case of somatic mosaicism after de novo mutation in MSH2 .

In 2017, we implemented CTNNA1 germline analysis in probands suspected of having hereditary diffuse gastric cancer. Here, we report the results from a retrospective series of 41 cases, including the identification of a new family with a CTNNA1 mutation and the first prophylactic total gastrectomy in an asymptomatic carrier after a normal upper endoscopy. Diffuse gastric cancer foci with loss of catenin alpha-1 expression were seen in the resected tissue, suggesting that CTNNA1 and CDH1 germline mutations behave in a similar manner. Life-changing prophylactic total gastrectomy should therefore also be considered in CTNNA1 mutation carriers.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare, autosomal dominant, vascular disorder. About 80% of cases are caused by pathogenic variants in ACVRL1 (also known as ALK1) and ENG, with the remaining cases being unexplained. We identified two variants, c.-79C>T and c.-68G>A, in the 5’UTR of ENG in two unrelated patients. They create upstream AUGs at the origin of upstream overlapping open reading frames (uoORFs) ending at the same stop codon. To assess the pathogenicity of these variants, we performed functional assays based on the expression of wild-type and mutant constructs in human cells and evaluated their effect on ALK1 activity in a BMP-response element assay. This assay is mandatory for molecular diagnosis and has been so far only applied to coding ENG variants. These variants were associated with a decrease of protein levels in HeLa and HUVEC cells and a decreased ability to activate ALK1. We applied the same experiments on three additional uoORF-creating variants (c.-142A>T, c.-127C>T and c.-10C>T) located in the 5’UTR of ENG and previously reported in HHT patients. We found that all the analyzed variants alter protein levels and function. Additional experiments relying on an artificial deletion in our mutated constructs show that identified uAUGs could initiate the translation indicating that the associated effect is translation-dependent. Overall, we have identified two 5’UTR ENG variations in HHT patients and shed new light on the role of upstream ORFs on ENG regulation. Our findings contribute to the amelioration of molecular diagnosis in HHT.

High-throughput sequencing (HTS) technologies are revolutionizing the research and molecular diagnosis landscape by allowing the exploration of millions of nucleotide sequences at an unprecedented scale. These technologies are of particular interest in the identification of genetic variations contributing to the risk of rare (Mendelian) and common (multifactorial) human diseases. So far, they have led to numerous successes in identifying rare disease-causing mutations in coding regions, but few in non-coding regions that include introns, untranslated (UTR), and intergenic regions. One class of neglected non-coding variations is that of 5′UTR variants that alter upstream open reading frames (upORFs) of the coding sequence (CDS) of a natural protein coding transcript. Following a brief summary of the molecular bases of the origin and functions of upORFs, we will first review known 5′UTR variations altering upORFs and causing rare cardiovascular disorders (CVDs). We will then investigate whether upORF-affecting single nucleotide polymorphisms could be good candidates for explaining association signals detected in the context of genome-wide association studies for common complex CVDs.

Background Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder characterized by multiple telangiectases and caused by germline disease-causing variants in the ENG (HHT1) , ACVRL1 (HHT2) and, to a lesser extent MADH4 and GDF2 , which encode proteins involved in the TGF-β/BMP9 signaling pathway. Common visceral complications of HHT are caused by pulmonary, cerebral, or hepatic arteriovenous malformations (HAVMs). There is large intrafamilial variability in the severity of visceral involvement, suggesting a role for modifier genes. The objective of the present study was to investigate the potential role of ENG , ACVRL1 , and of other candidate genes belonging to the same biological pathway in the development of HAVMs. Methods We selected 354 patients from the French HHT patient database who had one disease causing variant in either ENG or ACVRL1 and who underwent hepatic exploration. We first compared the distribution of the different types of variants with the occurrence of HAVMs. Then, we genotyped 51 Tag-SNPs from the Hap Map database located in 8 genes that encode proteins belonging to the TGF-β/BMP9 pathway ( ACVRL1, ENG, GDF2, MADH4, SMAD1, SMAD5, TGFB1, TGFBR1 ), as well as in two additional candidate genes ( PTPN14 and ADAM17 ). We addressed the question of a possible genetic association with the occurrence of HAVMs. Results The proportion of patients with germline ACVRL1 variants and the proportion of women were significantly higher in HHT patients with HAVMs. In the HHT2 group, HAVMs were more frequent in patients with truncating variants. Six SNPs (3 in ACVRL1 , 1 in ENG , 1 in SMAD5 , and 1 in ADAM17 ) were significantly associated with HAVMs. After correction for multiple testing, only one remained significantly associated (rs2277383). Conclusions In this large association study, we confirmed the strong relationship between ACVRL1 and the development of HAVMs. Common polymorphisms of ACVRL1 may also play a role in the development of HAVMs, as a modifying factor, independently of the disease-causing variants.