The enhancement of CRISPR/Cas9 gene editing using metformin.

The CRISPR/Cas9 technology is a revolutionary tool that can be used to edit the genome. Specifically, the genome of hematopoietic stem cells (HSCs) could be edited to correct monogenic blood disorders as well as produce immunotherapies. However, the efficiency of editing HSCs remains low. To overcome this hurdle, we set out to investigate the use of metformin, an FDA-approved drug, to enhance gene modification. We assessed the effect of metformin on the growth of two hematopoietic cell lines: a myeloid-erythroid leukemic cell line (K562 cells) representative of the myeloid population and an immortalized T lymphocyte cell line (Jurkat cells) representative of the lymphoid population. No significant difference in growth patterns was observed in concentrations up to 10 mM metformin in both cell lines. We then assessed the ability of two different concentrations of metformin (0.001 mM or 1 mM), based on our observations, to enhance both (1) the cutting efficiency of Cas9 and (2) the targeting efficiency with the use of a donor DNA repair template. The cutting efficiency of Cas9 was significantly enhanced in a total of five guide RNAs (four specific to a platelet locus and one specific to an erythroid locus) following treatment. In addition, an enhancement in targeting was observed with the use of a GFP-containing donor DNA repair template with both concentrations. Overall, a greater than two-fold increase in GFP expression was noted in cells treated with metformin. This suggests that metformin, an FDA-approved drug, could be added to existing protocols to enhance CRISPR/Cas9 gene editing.

Clinical and molecular heterogeneity of syndromic hypothalamic hamartoma.

Two children are presented who have a distinct syndrome of multiple buccolingual frenula, a stiff and short fifth finger with small nails, a hypothalamic hamartoma, mild to moderate neurological impairment, and mild endocrinological symptoms. No variant assessed to be pathogenic or likely pathogenic was detected in the GLI3 gene in either child. This syndrome appears to be distinct from the inherited Pallister-Hall syndrome associated with GLI3 variants, which is characterized by hypothalamic hamartoma, mesoaxial polydactyly, and other anomalies. In the individuals described here, manifestations outside of the central nervous system were milder and the mesoaxial polydactyly, which is common in individuals with Pallister-Hall syndrome, was absent. Instead, these children had multiple buccolingual frenula together with the unusual appearance of the fifth digit. It remains unclear whether these two individuals represent a separate nosologic entity or if they represent a milder manifestation of one of the more severe syndromes associated with a hypothalamic hamartoma.

The effect of histone deacetylase inhibitors on the efficiency of the CRISPR/Cas9 system.

The CRISPR/Cas9 technology is a prominent genome-editing tool capable of producing a double-strand break in the genome. However, the modification of hematopoietic stem cells via the homology-directed repair pathway is still inefficient. Therefore, we hypothesize that histone deacetylase inhibitors, such as valproic acid (VPA) and sodium butyrate (NaB), could enhance HDR efficiency by increasing the accessibility of the genome-editing machinery. To address the potential utilization of HDAC inhibitors therapeutically, we began by assessing the effect of VPA and NaB on two cell lines representative of the two hematopoietic stem cell lineages. No statistically significant effect on cell growth or viability was observed at concentrations as high as 5 mM. At a concentration as low as 0.005 mM NaB, an enhancement in CRISPR cutting efficiency was evidenced in both cell lines. This enhancement did not appear to be locus-specific. However, an enhancement in cutting efficiency following VPA treatment does appear to be. HDR efficiency was enhanced greater than two-fold with the use of 0.005 mM VPA. These results are promising and suggest the consideration of treatment with an HDAC inhibitor in CRISPR/Cas9 genome editing protocols.

Orally Bioavailable Macrocyclic Peptide That Inhibits Binding of PCSK9 to the Low Density Lipoprotein Receptor.

BACKGROUND: Inhibition of PCSK9 (proprotein convertase subtilisin/kexin type 9)-low density lipoprotein receptor interaction with injectable monoclonal antibodies or small interfering RNA lowers plasma low density lipoprotein-cholesterol, but despite nearly 2 decades of effort, an oral inhibitor of PCSK9 is not available. Macrocyclic peptides represent a novel approach to target proteins traditionally considered intractable to small-molecule drug design. METHODS: Novel mRNA display screening technology was used to identify lead chemical matter, which was then optimized by applying structure-based drug design enabled by novel synthetic chemistry to identify macrocyclic peptide (MK-0616) with exquisite potency and selectivity for PCSK9. Following completion of nonclinical safety studies, MK-0616 was administered to healthy adult participants in a single rising-dose Phase 1 clinical trial designed to evaluate its safety, pharmacokinetics, and pharmacodynamics. In a multiple-dose trial in participants taking statins, MK-0616 was administered once daily for 14 days to characterize the safety, pharmacokinetics, and pharmacodynamics (change in low density lipoprotein cholesterol). RESULTS: MK-0616 displayed high affinity (Ki = 5pM) for PCSK9 in vitro and sufficient safety and oral bioavailability preclinically to enable advancement into the clinic. In Phase 1 clinical studies in healthy adults, single oral doses of MK-0616 were associated with >93% geometric mean reduction (95% CI, 84-103) of free, unbound plasma PCSK9; in participants on statin therapy, multiple-oral-dose regimens provided a maximum 61% geometric mean reduction (95% CI, 43-85) in low density lipoprotein cholesterol from baseline after 14 days of once-daily dosing of 20 mg MK-0616. CONCLUSIONS: This work validates the use of mRNA display technology for identification of novel oral therapeutic agents, exemplified by the identification of an oral PCSK9 inhibitor, which has the potential to be a highly effective cholesterol lowering therapy for patients in need.

The significance of hindbrain herniation reversal following prenatal repair of neural tube defects.

OBJECTIVE: The aim of this study was to determine whether reversal of hindbrain herniation (HBH) on MRI following prenatal repair of neural tube defects (NTDs) is associated with reduced rates of ventriculoperitoneal (VP) shunt placement or endoscopic third ventriculostomy (ETV) within the 1st year of life. METHODS: This is a secondary analysis of prospectively collected data from all patients who had prenatal open repair of a fetal NTD at a single tertiary care center between 2012 and 2020. Patients were offered surgery according to inclusion criteria from the Management of Myelomeningocele Study (MOMS). Patients were excluded if they were lost to follow-up, did not undergo postnatal MRI, or underwent postnatal MRI without a report assessing hindbrain status. Patients with HBH reversal were compared with those without HBH reversal. The primary outcome assessed was surgical CSF diversion (i.e., VP shunt or ETV) within the first 12 months of life. Secondary outcomes included CSF leakage, repair dehiscence, CSF diversion prior to discharge from the neonatal intensive care unit (NICU), and composite neonatal morbidity. Demographic, prenatal sonographic, and operative characteristics as well as outcomes were assessed using standard univariate statistical methods. Multivariate logistic regression models were fit to assess for independent contributions to the primary and secondary outcomes. RESULTS: Following exclusions, 78 patients were available for analysis. Of these patients, 38 (48.7%) had HBH reversal and 40 (51.3%) had persistent HBH on postnatal MRI. Baseline demographic and preoperative ultrasound characteristics were similar between groups. The primary outcome of CSF diversion within the 1st year of life was similar between the two groups (42.1% vs 57.5%, p = 0.17). All secondary outcomes were also similar between groups. Patients who had occurrence of the primary outcome had greater presurgical lateral ventricle width than those who did not (16.1 vs 12.1 mm, p = 0.02) when HBH was reversed, but not when HBH was persistent (12.5 vs 10.7 mm, p = 0.49). In multivariate analysis, presurgical lateral ventricle width was associated with increased rates of CSF diversion before 12 months of life (adjusted OR 1.18, 95% CI 1.03-1.35) and CSF diversion prior to NICU discharge (adjusted OR 1.18, 95% CI 1.02-1.37). CONCLUSIONS: HBH reversal was not associated with decreased rates of CSF diversion in this cohort. Predictive accuracy of the anticipated benefits of prenatal NTD repair may not be augmented by the observation of HBH reversal on MRI.

Co-occurrence of Proteus syndrome and ventricular tachycardia cardiac arrest in a teenager.

Proteus syndrome is an extremely rare overgrowth condition caused by a somatic variant of the AKT1 gene. It can involve multiple organ systems though rarely is there symptomatic cardiac involvement. Fatty infiltration of the myocardium has been described but has not been reported to cause functional or conduction abnormalities. We present an individual with Proteus syndrome who suffered a sudden cardiac arrest.

IMiDs Augment CD3-Bispecific Antibody-Induced CD8+ T-Cell Cytotoxicity and Expansion by Enhancing IL2 Production.

Although CD3-bispecific antibodies have shown promising activity in the treatment of hematological cancers, insufficient T-cell costimulation may limit long-term responses. Immunomodulatory drugs (IMiDs), routinely used in treating multiple myeloma, possess pleiotropic antimyeloma properties and have been described to enhance T-cell responses similar to costimulatory signaling and may therefore have synergistic effects when combined with T-cell bispecifics. In this report, we demonstrate that IMiDs substantially enhance tumor cell killing induced by CD3 bispecifics and increase CD8+ T-cell proliferation and expansion. We further show that the beneficial effects of IMiDs on T-cell function and expansion are mediated by enhanced IL2 production by CD4+ T cells. Our studies provide mechanistic insight into the costimulatory properties of IMiDs and support combination treatments with T-cell agonist therapies in a broad spectrum of indications.

Updated variant curation expert panel criteria and pathogenicity classifications for 251 variants for RYR1-related malignant hyperthermia susceptibility.

The ClinGen malignant hyperthermia susceptibility (MHS) variant curation expert panel specified the American College of Medical Genetics and Genomics/Association of Molecular Pathologists (ACMG/AMP) criteria for RYR1-related MHS and a pilot analysis of 84 variants was published. We have now classified an additional 251 variants for RYR1-related MHS according to current ClinGen standards and updated the criteria where necessary. Criterion PS4 was modified such that individuals with multiple RYR1 variants classified as pathogenic (P), likely pathogenic (LP), or variant of uncertain significance (VUS) were not considered as providing evidence for pathogenicity. Criteria PS1 and PM5 were revised to consider LP variants at the same amino-acid residue as providing evidence for pathogenicity at reduced strength. Finally, PM1 was revised such that if PS1 or PM5 are used PM1, if applicable, should be downgraded to supporting. Of the 251 RYR1 variants, 42 were classified as P/LP, 16 as B/LB, and 193 as VUS. The primary driver of 175 VUS classifications was insufficient evidence supporting pathogenicity, rather than evidence against pathogenicity. Functional data supporting PS3/BS3 was identified for only 13 variants. Based on the posterior probabilities of pathogenicity and variant frequencies in gnomAD, we estimated the prevalence of individuals with RYR1-related MHS pathogenic variants to be between 1/300 and 1/1075, considerably higher than current estimates. We have updated ACMG/AMP criteria for RYR1-related MHS and classified 251 variants. We suggest that prioritization of functional studies is needed to resolve the large number of VUS classifications and allow for appropriate risk assessment. RYR1-related MHS pathogenic variants are likely to be more common than currently appreciated.

Discovery and Structure-Based Design of Macrocyclic Peptides Targeting STUB1.

Recent evidence suggests that deletion of STUB1─a pivotal negative regulator of interferon-γ sensing─may potentially clear malignant cells. However, current studies rely primarily on genetic approaches, as pharmacological inhibitors of STUB1 are lacking. Identifying a tool compound will be a step toward validating the target in a broader therapeutic sense. Herein, screening more than a billion macrocyclic peptides resulted in STUB1 binders, which were further optimized by a structure-enabled in silico design. The strategy to replace the macrocyclic peptides' hydrophilic and solvent-exposed region with a hydrophobic scaffold improved cellular permeability while maintaining the binding conformation. Further substitution of the permeability-limiting terminal aspartic acid with a tetrazole bioisostere retained the binding to a certain extent while improving permeability, suggesting a path forward. Although not optimal for cellular study, the current lead provides a valuable template for further development into selective tool compounds for STUB1 to enable target validation.

Accelerated Identification of Cell Active KRAS Inhibitory Macrocyclic Peptides using Mixture Libraries and Automated Ligand Identification System (ALIS) Technology.

Macrocyclic peptides can disrupt previously intractable protein-protein interactions (PPIs) relevant to oncology targets such as KRAS. Early hits often lack cellular activity and require meticulous improvement of affinity, permeability, and metabolic stability to become viable leads. We have validated the use of the Automated Ligand Identification System (ALIS) to screen oncogenic KRASG12D (GDP) against mass-encoded mini-libraries of macrocyclic peptides and accelerate our structure-activity relationship (SAR) exploration. These mixture libraries were generated by premixing various unnatural amino acids without the need for the laborious purification of individual peptides. The affinity ranking of the peptide sequences provided SAR-rich data sets that led to the selection of novel potency-enhancing substitutions in our subsequent designs. Additional stability and permeability optimization resulted in the identification of peptide 7 that inhibited pERK activity in a pancreatic cancer cell line. More broadly, this methodology offers an efficient alternative to accelerate the fastidious hit-to-lead optimization of PPI peptide inhibitors.

Erratum: Orofacial overgrowth with peripheral nerve enlargement and perineuriomatous pseudo-onion bulb proliferations is part of the PIK3CA-related overgrowth spectrum.

[This corrects the article DOI: 10.1016/j.xhgg.2020.100009.].

Somatic PIK3R1 variation as a cause of vascular malformations and overgrowth.

PURPOSE: Somatic activating variants in the PI3K-AKT pathway cause vascular malformations with and without overgrowth. We previously reported an individual with capillary and lymphatic malformation harboring a pathogenic somatic variant in PIK3R1, which encodes three PI3K complex regulatory subunits. Here, we investigate PIK3R1 in a large cohort with vascular anomalies and identify an additional 16 individuals with somatic mosaic variants in PIK3R1. METHODS: Affected tissue from individuals with vascular lesions and overgrowth recruited from a multisite collaborative network was studied. Next-generation sequencing targeting coding regions of cell-signaling and cancer-associated genes was performed followed by assessment of variant pathogenicity. RESULTS: The phenotypic and variant spectrum associated with somatic variation in PIK3R1 is reported herein. Variants occurred in the inter-SH2 or N-terminal SH2 domains of all three PIK3R1 protein products. Phenotypic features overlapped those of the PIK3CA-related overgrowth spectrum (PROS). These overlapping features included mixed vascular malformations, sandal toe gap deformity with macrodactyly, lymphatic malformations, venous ectasias, and overgrowth of soft tissue or bone. CONCLUSION: Somatic PIK3R1 variants sharing attributes with cancer-associated variants cause complex vascular malformations and overgrowth. The PIK3R1-associated phenotypic spectrum overlaps with PROS. These data extend understanding of the diverse phenotypic spectrum attributable to genetic variation in the PI3K-AKT pathway.

Variant curation expert panel recommendations for RYR1 pathogenicity classifications in malignant hyperthermia susceptibility.

PURPOSE: As a ClinGen Expert Panel (EP) we set out to adapt the American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology (AMP) pathogenicity criteria for classification of RYR1 variants as related to autosomal dominantly inherited malignant hyperthermia (MH). METHODS: We specified ACMG/AMP criteria for variant classification for RYR1 and MH. Proposed rules were piloted on 84 variants. We applied quantitative evidence calibration for several criteria using likelihood ratios based on the Bayesian framework. RESULTS: Seven ACMG/AMP criteria were adopted without changes, nine were adopted with RYR1-specific modifications, and ten were dropped. The in silico (PP3 and BP4) and hotspot criteria (PM1) were evaluated quantitatively. REVEL gave an odds ratio (OR) of 23:1 for PP3 and 14:1 for BP4 using trichotomized cutoffs of ≥0.85 (pathogenic) and ≤0.5 (benign). The PM1 hotspot criterion had an OR of 24:1. PP3 and PM1 were implemented at moderate strength. Applying the revised ACMG/AMP criteria to 44 recognized MH variants, 29 were classified as pathogenic, 13 as likely pathogenic, and 2 as variants of uncertain significance. CONCLUSION: Curation of these variants will facilitate classification of RYR1/MH genomic testing results, which is especially important for secondary findings analyses. Our approach to quantitatively calibrating criteria is generalizable to other variant curation expert panels.

Anti-LYPD1/CD3 T-Cell-Dependent Bispecific Antibody for the Treatment of Ovarian Cancer.

Ovarian cancer is a diverse class of tumors with very few effective treatment options and suboptimal response rates in early clinical studies using immunotherapies. Here we describe LY6/PLAUR domain containing 1 (LYPD1) as a novel target for therapeutic antibodies for the treatment of ovarian cancer. LYPD1 is broadly expressed in both primary and metastatic ovarian cancer with ∼70% prevalence in the serous cancer subset. Bispecific antibodies targeting CD3 on T cells and a tumor antigen on cancer cells have demonstrated significant clinical activity in hematologic cancers. We have developed an anti-LYPD1/CD3 T-cell-dependent bispecific antibody (TDB) to redirect T-cell responses to LYPD1 expressing ovarian cancer. Here we characterize the nonclinical pharmacology of anti-LYPD1/CD3 TDB and show induction of a robust polyclonal T-cell activation and target dependent killing of LYPD1 expressing ovarian cancer cells resulting in efficient in vivo antitumor responses in PBMC reconstituted immune-deficient mice and human CD3 transgenic mouse models. Anti-LYPD1/CD3 TDB is generally well tolerated at high-dose levels in mice, a pharmacologically relevant species, and showed no evidence of toxicity or damage to LYPD1 expressing tissues.

Variant Classification Concordance using the ACMG-AMP Variant Interpretation Guidelines across Nine Genomic Implementation Research Studies.

Harmonization of variant pathogenicity classification across laboratories is important for advancing clinical genomics. The two CLIA-accredited Electronic Medical Record and Genomics Network sequencing centers and the six CLIA-accredited laboratories and one research laboratory performing genome or exome sequencing in the Clinical Sequencing Evidence-Generating Research Consortium collaborated to explore current sources of discordance in classification. Eight laboratories each submitted 20 classified variants in the ACMG secondary finding v.2.0 genes. After removing duplicates, each of the 158 variants was annotated and independently classified by two additional laboratories using the ACMG-AMP guidelines. Overall concordance across three laboratories was assessed and discordant variants were reviewed via teleconference and email. The submitted variant set included 28 P/LP variants, 96 VUS, and 34 LB/B variants, mostly in cancer (40%) and cardiac (27%) risk genes. Eighty-six (54%) variants reached complete five-category (i.e., P, LP, VUS, LB, B) concordance, and 17 (11%) had a discordance that could affect clinical recommendations (P/LP versus VUS/LB/B). 21% and 63% of variants submitted as P and LP, respectively, were discordant with VUS. Of the 54 originally discordant variants that underwent further review, 32 reached agreement, for a post-review concordance rate of 84% (118/140 variants). This project provides an updated estimate of variant concordance, identifies considerations for LP classified variants, and highlights ongoing sources of discordance. Continued and increased sharing of variant classifications and evidence across laboratories, and the ongoing work of ClinGen to provide general as well as gene- and disease-specific guidance, will lead to continued increases in concordance.

Serious Illness Conversations in Pediatrics: A Case Review.

The Serious Illness Conversation Guide program developed by Ariadne Labs, a Joint Center for Health Systems Innovation, includes a list of patient-centered questions designed to assist clinicians to gain a more thorough understanding of their patient's life in order to inform future care decisions. In July 2017, specialist pediatric palliative care clinicians at Canuck Place Children's Hospice (CPCH) (Vancouver, BC, Canada), adapted the original guide to use with parents of children with serious illness. This tool is referred to as the Serious Illness Conversation Guide-Peds (SICG-Peds). Using the SICG-Peds, along with enhanced communication skills, can help illuminate the parents' (child's) understanding of illness and the values they hold. Expanding the application of the guide will promote goal-based, efficient, comprehensive and consistent communication between families and clinicians and help ensure that seriously ill children receive care that is tailored to their needs through the disease trajectory. This paper explores the guide through the lens of a case study. The steps-seeking permission, assessing understanding, sharing prognosis and exploring key topics (hopes, fears, strengths, critical abilities and trade-offs)-as well as formulating clinician recommendations, are described.

Target arm affinities determine preclinical efficacy and safety of anti-HER2/CD3 bispecific antibody.

Systemic cytokine release and on-target/off-tumor toxicity to normal tissues are the main adverse effects limiting the clinical utility of T cell-redirecting therapies. This study was designed to determine how binding affinity for CD3 and tumor target HER2 impact the efficacy and nonclinical safety of anti-HER2/CD3 T cell-dependent antibodies (TDBs). Affinity was found to be a major determinant for the overall tolerability. Higher affinity for CD3 associated with rapidly elevated peripheral cytokine concentrations, weight loss in mice, and poor tolerability in cynomolgus monkeys. A TDB with lower CD3 affinity was better tolerated in cynomolgus monkeys compared with a higher CD3-affinity TDB. In contrast to tolerability, T cell binding affinity had only limited impact on in vitro and in vivo antitumor activity. High affinity for HER2 was critical for the tumor-killing activity of anti-HER2/CD3 TDBs, but higher HER2 affinity also associated with a more severe toxicity profile, including cytokine release and damage to HER2-expressing tissues. The tolerability of the anti-HER2/CD3 was improved by implementing a dose-fractionation strategy. Fine-tuning the affinities for both the tumor target and CD3 is likely a valuable strategy for achieving maximal therapeutic index of CD3 bispecific antibodies.

Factors associated with provision of smoking cessation support to pregnant women - a cross-sectional survey of midwives in New South Wales, Australia.

BACKGROUND: Smoking is the most important preventable cause of adverse pregnancy outcomes, but provision of smoking cessation support (SCS) to pregnant women is poor. We examined the association between midwives' implementation of SCS (5As - Ask, Advise, Assess, Assist, Arrange follow-up) and reported barriers/enablers to implementation. METHODS: On-line anonymous survey of midwives providing antenatal care in New South Wales (NSW), Australia, assessing provision of the 5As and barriers/enablers to their implementation, using the Theoretical Domains Framework (TDF). Factor analyses identified constructs underlying the 5As; and barriers/enablers. Multivariate general linear models examined relationships between the barrier/enabler factors and the 5As factors. RESULTS: Of 750 midwives invited, 150 (20%) participated. Respondents more commonly reported Asking and Assessing than Advising, Assisting, or Arranging follow-up (e.g. 77% always Ask smoking status; 17% always Arrange follow-up). Three 5As factors were identified- 'Helping', 'Assessing quitting' and 'Assessing dependence'. Responses to barrier/enabler items showed greater knowledge, skills, intentions, and confidence with Assessment than Assisting; endorsement for SCS as a priority and part of midwives' professional role; and gaps in training and organisational support for SCS. Nine barrier/enabler factors were identified. Of these, the factors of 'Capability' (knowledge, skills, confidence); 'Work Environment' (service has resources, capacity, champions and values SCS) and 'Personal priority' (part of role and a priority) predicted 'Helping'. CONCLUSION: The TDF enabled systematic identification of barriers to providing SCS, and the multivariate models identified key contributors to poor implementation. Combined with qualitative data, these results have been mapped to intervention components to develop a comprehensive intervention to improve SCS.

Orofacial overgrowth with peripheral nerve enlargement and perineuriomatous pseudo-onion bulb proliferations is part of the PIK3CA-related overgrowth spectrum.

Individuals with orofacial asymmetry due to mucosal overgrowths, ipsilateral bone and dental aberrations with perineurial hyperplasia and/or perineuriomatous pseudo-onion bulb proliferations, comprise a recognizable clinical entity. In this article, we describe three individuals with this clinical entity and mosaic PIK3CA variants c.3140A>G (p. His1047Arg), c.328_330delGAA (p. Glu110del), and c.1353_1364del (p.Glu453_Leu456del). We conclude that the identification of these mosaic variants in individuals with orofacial asymmetry presenting histopathologically perineurial hyperplasia and/or intraneural pseudo-onion bulb perineurial cell proliferations supports the inclusion of this clinical entity in the PIK3CA-related overgrowth spectrum.

Health behaviors among unaffected participants following receipt of variants of uncertain significance in cardiomyopathy-associated genes.

PURPOSE: Studies on returning variants of uncertain significance (VUS) results have predominantly included patients with a personal or family history of cancer and cancer-associated gene VUS. This study examined health behaviors among participants with cardiomyopathy-associated gene VUS, but without a personal history of cardiomyopathy. METHODS: Sixty-eight eligible participants without apparent cardiomyopathy but with VUS in cardiomyopathy-associated genes completed a survey of health behaviors, disclosure, distress, uncertainty, positive experiences, decisional conflict, and perceived value. The medical records of participants who reported cardiac testing because of their VUS were reviewed for testing indication(s). RESULTS: Two participants had cardiac testing due to their VUS alone. Four had cardiac testing because of their VUS and other clinical indications. Twelve changed health behaviors, including one participant who was subsequently diagnosed with cardiomyopathy. Distress, uncertainty, and decisional conflict were low (means = 1.2, 4.2, and 24.5 (scale ranges = 0-30, 0-45, and 15-75), respectively), and positive experiences and perceived value were moderate (means = 12.4 and 14.4 (scale ranges = 0-20 and 4-20), respectively). Greater perceived value was associated with greater likelihood to engage in health behaviors (P = 0.04). CONCLUSION: Positive VUS results can be returned to apparently unaffected individuals with modest use of healthcare resources, minimal behavioral changes, and favorable psychological reactions.