Somatic RIT1 delins in arteriovenous malformations hyperactivate RAS-MAPK signaling amenable to MEK inhibition.

Arteriovenous malformations (AVM) are benign vascular anomalies prone to pain, bleeding, and progressive growth. AVM are mainly caused by mosaic pathogenic variants of the RAS-MAPK pathway. However, a causative variant is not identified in all patients. Using ultra-deep sequencing, we identified novel somatic RIT1 delins variants in lesional tissue of three AVM patients. RIT1 encodes a RAS-like protein that can modulate RAS-MAPK signaling. We expressed RIT1 variants in HEK293T cells, which led to a strong increase in ERK1/2 phosphorylation. Endothelial-specific mosaic overexpression of RIT1 delins in zebrafish embryos induced AVM formation, highlighting their functional importance in vascular development. Both ERK1/2 hyperactivation in vitro and AVM formation in vivo could be suppressed by pharmacological MEK inhibition. Treatment with the MEK inhibitor trametinib led to a significant decrease in bleeding episodes and AVM size in one patient. Our findings implicate RIT1 in AVM formation and provide a rationale for clinical trials with targeted treatments.

Patient-specific risk factors for reintervention following primary endovascular treatment of iliac artery disease.

OBJECTIVE: Predictive models for reintervention may guide clinicians to optimize selection, education, and follow-up of patients undergoing endovascular iliac revascularization. Although the impact of lesion- and device-related characteristics on iliac restenosis and reintervention risk is well-defined, data on patient-specific risk factors are scarce and conflicting. This study aimed to explore the value of patient-related factors in predicting the need for clinically driven target-vessel revascularization (CD-TVR) in patients undergoing primary endovascular treatment of iliac artery disease. METHODS: Consecutively enrolled patients undergoing endovascular revascularization for symptomatic iliac artery disease at a tertiary vascular referral center between January 2008 and June 2020 were retrospectively analyzed. Primary and secondary outcomes were CD-TVR occurrence within 24 months and time to CD-TVR, respectively. Patients who died or did not require CD-TVR within 24 months were censored at the date of death or at 730 days, respectively. Multiple imputation was used to account for missing data in primary analyses. RESULTS: A total of 1538 iliac interventions were performed in 1113 patients (26% females; 68 years). CD-TVR occurred in 108 limbs (74 patients; 7.0%) with a median time to CD-TVR of 246 days. On multivariable analysis, increasing age was associated with lower likelihood of CD-TVR (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.50-0.83; P = .001) and decreased risk of CD-TVR at any given time (hazard ratio [HR], 0.66; 95% CI, 0.52-0.84; P = .001). Similarly, a lower likelihood of CD-TVR (OR, 0.75; 95% CI, 0.59-0.95; P = .017) and decreased risk of CD-TVR at any given time (HR, 0.73; 95% CI, 0.58-0.93; P = .009) were observed with higher glomerular filtration rates. Lastly, revascularization of common vs external iliac artery disease was associated with lower likelihood of CD-TVR (OR, 0.48; 95% CI, 0.24-0.93; P = .030) and decreased risk of CD-TVR at any given time (HR, 0.48; 95% CI, 0.25-0.92; P = .027). No associations were observed between traditional cardiovascular risk factors (sex, hypertension, higher low-density lipoprotein cholesterol, higher hemoglobin A1c, smoking) and CD-TVR. CONCLUSIONS: In this retrospective cohort study, younger age, impaired kidney function, and external iliac artery disease were associated with CD-TVR. Traditional markers of cardiovascular risk were not seen to predict reintervention.

Combination of Model for End-Stage Liver Disease (MELD) and Sarcopenia predicts mortality after transjugular intrahepatic portosystemic shunt (TIPS).

TIPS is the most effective treatment for portal hypertension. Patient selection remains important to achieving optimal post-TIPS outcomes. The study evaluates 1-year mortality factors in cirrhotic patients receiving TIPS. METHODS: 87 cirrhotic patients received a TIPS between 2015 - 2021. Predictors of 1-year and overall mortality were assessed by estimating cumulative incidence functions and Grey's test to adjust for liver transplantation as a risk competing with mortality. Variables with p < 0.05 were checked for collinearity and included in the multivariate Cox proportional hazards model. Model discrimination was evaluated by calculating the area under the ROC curve. RESULTS: 87 patients were included (68% men; 22% ≥70 years). ALD was the primary cirrhosis cause. Most patients were Child-Pugh class B, MELD-Na score was 13.6 ± 6.0 points. The most frequent indication for TIPS was bleeding (51.7%), followed by refractory ascites (42.5%). The variables positively associated with mortality in univariate analysis were ascites, clinically overt sarcopenia and MELD-Na score, while ongoing nutritional supplementation improved survival. In the multivariate analysis, only clinically overt sarcopenia and MELD-Na score remained independently associated with mortality. A MELD-Na/sarcopenia model demonstrated a good discrimination, AUROC: 0.86 (95% CI 0.77 - 0.95). CONCLUSION: MELD-Na score, and sarcopenia were significantly associated with 1-year survival in cirrhotic patients who received TIPS.

A proposal for a revision of the phlebographic classification of congenital venous malformations.

Background: Venous malformation (VM) is the most frequent type of congenital vascular malformation. In terms of functional outcome local sclerotherapy remains the most important therapeutic tool. For planning and correct estimation and prevention of complications, an exact anatomical classification of the VM is crucial. Not only the drainage, as assessed in the established classification, but also the phlebographic aspect of the internal VM structure itself plays a decisive role. In order to integrate this aspect, we aim to validate a proposal for a revised phlebographic VM classification distinguishing non-lacunar (a) and lacunar (b) types. Methods: We retrospectively analyzed all patients with VM in whom a direct puncture phlebography was performed in our clinic between 2009 and 2018 to assess morphology and flow characteristics. Phlebographic assessment included: (I) differentiation of non-lacunar vs. lacunar type; (II) drainage assignment according to the existing classification; (III) adjusted classification combining both. Inter-reader agreement was measured in percentage as well as by the Cohen's kappa coefficient (κ). Results: Overall 26 patients were classified as non-lacunar (a) and 41 patients as lacunar (b) VM. For this categorization, inter-reader agreement was 96% (κ=0.91). Classical Puig classification into types I, II, III and IV showed 87% inter-reader agreement (κ=0.78). For the adjusted classification adding the non-lacunar or lacunar characteristic to type I-IV an agreement of 82% (κ=0.77) was achieved. Conclusions: Phlebographic differentiation into non-lacunar and lacunar VM is feasible and reliable to distinguish phenotypic subgroups of patients with VM. We therefore propose to integrate this parameter of the internal VM structure into the existing classification.

A cost-effective sequencing method for genetic studies combining high-depth whole exome and low-depth whole genome.

Whole genome sequencing (WGS) at high-depth (30X) allows the accurate discovery of variants in the coding and non-coding DNA regions and helps elucidate the genetic underpinnings of human health and diseases. Yet, due to the prohibitive cost of high-depth WGS, most large-scale genetic association studies use genotyping arrays or high-depth whole exome sequencing (WES). Here we propose a cost-effective method which we call "Whole Exome Genome Sequencing" (WEGS), that combines low-depth WGS and high-depth WES with up to 8 samples pooled and sequenced simultaneously (multiplexed). We experimentally assess the performance of WEGS with four different depth of coverage and sample multiplexing configurations. We show that the optimal WEGS configurations are 1.7-2.0 times cheaper than standard WES (no-plexing), 1.8-2.1 times cheaper than high-depth WGS, reach similar recall and precision rates in detecting coding variants as WES, and capture more population-specific variants in the rest of the genome that are difficult to recover when using genotype imputation methods. We apply WEGS to 862 patients with peripheral artery disease and show that it directly assesses more known disease-associated variants than a typical genotyping array and thousands of non-imputable variants per disease-associated locus.