Association of the V122I Hereditary Transthyretin Amyloidosis Genetic Variant With Heart Failure Among Individuals of African or Hispanic/Latino Ancestry

Carpal Tunnel Syndrome and Transthyretin Amyloidosis in the All of Us Research Program

OBJECTIVE

To evaluate the association of carpal tunnel syndrome (CTS) with incident heart failure and incident amyloidosis and to assess the risk of CTS in pathogenic TTR genetic variant carriers.

METHODS

This prospective cohort study included multiethnic US adults 18 years of age and older without prevalent heart failure and amyloidosis with available genotypic data from the All of Us Research Program. The primary outcomes were incident heart failure and incident amyloidosis. The association of incident heart failure and incident amyloidosis with CTS was assessed using multivariable adjusted Cox models accounting for age, sex, race and ethnicity, obesity, hypertension, diabetes, statin use, and smoking status.

RESULTS

Of the 166,987 individuals included, the median age was 54 (38 to 66) years; 105,279 (63.0%) were female, and 92,780 (55.6%) were non-Hispanic White individuals; CTS was identified in 12,407 (7.4%) individuals. Compared with individuals without CTS, the adjusted hazard ratio for incident heart failure was 1.13 (95% CI, 1.02 to 1.26) in individuals with CTS. The risk of amyloidosis was ∼3-fold higher (adjusted hazard ratio, 2.86; 95% CI, 1.71 to 4.77) in individuals with CTS compared with those without CTS. Individuals carrying a pathogenic TTR variant had an approximately 40% higher risk (adjusted hazard ratio, 1.38; 95% CI, 1.16 to 1.65) for development of CTS compared with noncarriers.

CONCLUSION

Cardiac amyloidosis screening programs may use CTS as a sentinel event and use genetic testing to identify individuals at a higher risk of TTR amyloidosis.

Cardiovascular Burden of the V142I Transthyretin Variant

Importance

Individual cohort studies concur that the amyloidogenic V142I variant of the transthyretin (TTR) gene, present in 3% to 4% of US Black individuals, increases heart failure (HF) and mortality risk. Precisely defining carrier risk across relevant clinical outcomes and estimating population burden of disease are important given established and emerging targeted treatments.

Objectives

To better define the natural history of disease in carriers across mid to late life, assess variant modifiers, and estimate cardiovascular burden to the US population.

Design, Setting, and Participants

A total of 23 338 self-reported Black participants initially free from HF were included in 4 large observational studies across the US (mean [SD], 15.5 [8.2] years of follow-up). Data analysis was performed between May 2023 and February 2024.

Exposure

V142I carrier status (n = 754, 3.2%).

Main Outcomes and Measures

Hospitalizations for HF (including subtypes of reduced and preserved ejection fraction) and all-cause mortality. Outcomes were analyzed by generating 10-year hazard ratios for each age between 50 and 90 years. Using actuarial methods, mean survival by carrier status was estimated and applied to the 2022 US population using US Census data.

Results

Among the 23 338 participants, the mean (SD) age at baseline was 62 (9) years and 76.7% were women. Ten-year carrier risk increased for HF hospitalization by age 63 years, predominantly driven by HF with reduced ejection fraction, and 10-year all-cause mortality risk increased by age 72 years. Only age (but not sex or other select variables) modified risk with the variant, with estimated reductions in longevity ranging from 1.9 years (95% CI, 0.6-3.1) at age 50 to 2.8 years (95% CI, 2.0-3.6) at age 81. Based on these data, 435 851 estimated US Black carriers between ages 50 and 95 years are projected to cumulatively lose 957 505 years of life (95% CI, 534 475-1 380 535) due to the variant.

Conclusions and Relevance

Among self-reported Black individuals, male and female V142I carriers faced similar and substantial risk for HF hospitalization, predominantly with reduced ejection fraction, and death, with steep age-dependent penetrance. Delineating the individual contributions of, and complex interplay among, the V142I variant, ancestry, the social construct of race, and biological or social determinants of health to cardiovascular disease merits further investigation.

Race and Socioeconomic Status Impact Diagnosis and Clinical Outcomes in Transthyretin Cardiac Amyloidosis

Background

Transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with significant mortality. The Val122Ile variant, highly prevalent in Black patients, portends poorer survival compared with other ATTR-CM subtypes. Although Val122Ile is biologically more aggressive, the contribution of race and socioeconomic status (SES) to disease outcomes in patients with ATTR-CM is undefined.

Objectives

The aim of this study was to evaluate the impact of race and SES on clinical outcomes in patients with ATTR-CM.

Methods

Patients with ATTR-CM who received care at Johns Hopkins Hospital between 2006 and 2022 were included. SES was assessed using area deprivation index (ADI). Associations of race and ADI with heart failure (HF) hospitalization and/or death were measured using multivariable logistic or Cox proportional hazards models.

Results

Of 282 patients, 225 (80%) were men, and 129 (46%) were Black. Black vs White patients disproportionately constituted the highest ADI (most deprived) category (66% vs 28%; P = 0.004), and Black patients were more likely to have HF hospitalization or death over 5 years compared with White patients (log-rank P < 0.001). Among those with ADI >25, Black patients had a significantly greater hazard of HF hospitalization or death compared with White patients, independent of disease stage at diagnosis (HR: 2.77; 95% CI: 1.45-5.32; P = 0.002).

Conclusions

Black patients with low SES may be at greater risk for underdiagnosis and adverse outcomes compared with White patients. Ongoing efforts are needed to improve outcomes in this subset of patients with ATTR-CM.

Circulating transthyretin and retinol binding protein 4 levels among middle-age V122I TTR carriers in the general population

BACKGROUND

Hereditary transthyretin cardiac amyloidosis (ATTRv-CA) has a long latency phase before clinical onset, creating a need to identify subclinical disease. We hypothesized circulating transthyretin (TTR) and retinol binding protein 4 (RBP4) levels would be associated with TTR carrier status and correlated with possible evidence of subclinical ATTRv-CA.

METHODS

TTR and RBP4 were measured in blood samples from V122I TTR carriers and age-, sex- and race-matched non-carrier controls (1:2 matching) among Dallas Heart Study participants (phases 1 (DHS-1) and 2 (DHS-2)). Multivariable linear regression models determined factors associated with TTR and RBP4.

RESULTS

There were 40 V122I TTR carriers in DHS-1 and 54 V122I TTR carriers in DHS-2. In DHS-1 and DHS-2, TTR was lower in V122I TTR carriers (p < .001 for both), and RBP4 in DHS-2 was lower in V122I TTR carriers than non-carriers (p = .002). Among V122I TTR carriers, TTR was negatively correlated with markers of kidney function, and limb lead voltage (p < .05 for both) and TTR and RBP4 were correlated with atrial volume in DHS-2 (p < .05).

CONCLUSIONS

V122I TTR carrier status is independently associated with lower TTR and RBP4 in comparison with non-carriers. These findings support the hypothesis that TTR and RBP4 may correlate with evidence of subclinical ATTRv-CA.

Genome-first evaluation with exome sequence and clinical data uncovers underdiagnosed genetic disorders in a large healthcare system

Population-based genomic screening may help diagnose individuals with disease-risk variants. Here, we perform a genome-first evaluation for nine disorders in 29,039 participants with linked exome sequences and electronic health records (EHRs). We identify 614 individuals with 303 pathogenic/likely pathogenic or predicted loss-of-function (P/LP/LoF) variants, yielding 644 observations; 487 observations (76%) lack a corresponding clinical diagnosis in the EHR. Upon further investigation, 75 clinically undiagnosed observations (15%) have evidence of symptomatic untreated disease, including familial hypercholesterolemia (3 of 6 [50%] undiagnosed observations with disease evidence) and breast cancer (23 of 106 [22%]). These genetic findings enable targeted phenotyping that reveals new diagnoses in previously undiagnosed individuals. Disease yield is greater with variants in penetrant genes for which disease is observed in carriers in an independent cohort. The prevalence of P/LP/LoF variants exceeds that of clinical diagnoses, and some clinically undiagnosed carriers are discovered to have disease. These results highlight the potential of population-based genomic screening.

Genetically transitional disease: conceptual understanding and applicability to rheumatic disease

In genomic medicine, the concept of genetically transitional disease (GTD) refers to cases in which gene mutation is necessary but not sufficient to cause disease. In this Perspective, we apply this novel concept to rheumatic diseases, which have been linked to hundreds of genetic variants via association studies. These variants are in the 'grey zone' between monogenic variants with large effect sizes and common susceptibility alleles with small effect sizes. Among genes associated with rare autoinflammatory diseases, many low-frequency and/or low-penetrance variants are known to increase susceptibility to systemic inflammation. In autoimmune diseases, hundreds of HLA and non-HLA genetic variants have been revealed to be modest- to moderate-risk alleles. These diseases can be reclassified as GTDs. The same concept could apply to many other human diseases. GTD could improve the reporting of genetic testing results, diagnostic yields, genetic counselling and selection of therapy, as well as facilitating research using a novel approach to human genetic diseases.

Race, Genotype, and Prognosis in Black Patients With Transthyretin Cardiac Amyloidosis

Previous studies suggest worse outcomes in patients with variant transthyretin cardiac amyloidosis (ATTR-CA) because of valine-to-isoleucine substitution at Position 122 (V122I) (ATTRv-CA) compared with patients with wild-type (WT) disease (ATTRwt-CA). Given V122I is almost exclusively found in Black patients, it is unclear if this is attributable to the biology of genotype or racial differences. Patients with ATTR-CA diagnosed between January 2001 and August 2021 were characterized into 3 categories: (1) White with ATTRwt-CA (White-WT); (2) Black with V122I ATTRv-CA (Black-V122I), and (3) Black with ATTRwt-CA (Black-WT). Event-free survival (composite of death, left ventricular assist device, or cardiac transplant) was evaluated using univariable and multivariable analyses over a median follow-up of 1.6 (0.7 to 2.90) years. Of 694 ATTR-CA patients, 502 (72%) were White-WT, 139 Black-V122I (20%), and 53 Black-WT (8%). Notably, 28% of Black patients with ATTR-CA had WT disease and not the V122I variant. Using multivariable modeling to adjust for several prognostic features, Black-V122I had higher risk of the composite adverse outcome compared with a grouped cohort of patients with WT disease (White-WT and Black-WT) (hazard ratio [HR] 1.82, confidence interval [CI] 1.30-2.56, p < 0.001). Furthermore, the Black cohort as a whole (Black-V122I and Black-WT) demonstrated greater risk of adverse outcomes compared with White-WT (HR 1.63, CI 1.19-2.24, p = 0.002). Black-V122I had greater risk of the primary end point compared with White-WT (HR 1.80, CI 1.27-2.56, p = 0.001). Black patients with ATTR-CA have worse event-free survival than White-WT despite risk adjustment. However, it remains unclear whether this is driven by differences in race or genotype given the smaller number of Black-WT patients. Approximately one-quarter of Black patients had WT, of which a greater proportion were female compared with White-WT.

Clinical spectrum of Transthyretin amyloidogenic mutations among diverse population origins

PURPOSE

Coding mutations in the Transthyretin (TTR) gene cause a hereditary form of amyloidosis characterized by a complex genotype-phenotype correlation with limited information regarding differences among worldwide populations.

METHODS

We compared 676 diverse individuals carrying TTR amyloidogenic mutations (rs138065384, Phe44Leu; rs730881165, Ala81Thr; rs121918074, His90Asn; rs76992529, Val122Ile) to 12,430 non-carriers matched by age, sex, and genetically-inferred ancestry to assess their clinical presentations across 1,693 outcomes derived from electronic health records in UK biobank.

RESULTS

In individuals of African descent (AFR), Val122Ile mutation was linked to multiple outcomes related to the circulatory system (fold-enrichment = 2.96, p = 0.002) with the strongest associations being cardiac congenital anomalies (phecode 747.1, p = 0.003), endocarditis (phecode 420.3, p = 0.006), and cardiomyopathy (phecode 425, p = 0.007). In individuals of Central-South Asian descent (CSA), His90Asn mutation was associated with dermatologic outcomes (fold-enrichment = 28, p = 0.001). The same TTR mutation was linked to neoplasms in European-descent individuals (EUR, fold-enrichment = 3.09, p = 0.003). In EUR, Ala81Thr showed multiple associations with respiratory outcomes related (fold-enrichment = 3.61, p = 0.002), but the strongest association was with atrioventricular block (phecode 426.2, p = 2.81 × 10- 4). Additionally, the same mutation in East Asians (EAS) showed associations with endocrine-metabolic traits (fold-enrichment = 4.47, p = 0.003). In the cross-ancestry meta-analysis, Val122Ile mutation was associated with peripheral nerve disorders (phecode 351, p = 0.004) in addition to cardiac congenital anomalies (fold-enrichment = 6.94, p = 0.003).

CONCLUSIONS

Overall, these findings highlight that TTR amyloidogenic mutations present ancestry-specific and ancestry-convergent associations related to a range of health domains. This supports the need to increase awareness regarding the range of outcomes associated with TTR mutations across worldwide populations to reduce misdiagnosis and delayed diagnosis of TTR-related amyloidosis.

Cardiac Amyloidosis Due to Transthyretin Protein: A Review

Importance

Systemic amyloidosis from transthyretin (ATTR) protein is the most common type of amyloidosis that causes cardiomyopathy.

Observations

Transthyretin (TTR) protein transports thyroxine (thyroid hormone) and retinol (vitamin A) and is synthesized predominantly by the liver. When the TTR protein misfolds, it can form amyloid fibrils that deposit in the heart causing heart failure, heart conduction block, or arrhythmia such as atrial fibrillation. The biological processes by which amyloid fibrils form are incompletely understood but are associated with aging and, in some patients, affected by inherited variants in the TTR genetic sequence. ATTR amyloidosis results from misfolded TTR protein deposition. ATTR can occur in association with normal TTR genetic sequence (wild-type ATTR) or with abnormal TTR genetic sequence (variant ATTR). Wild-type ATTR primarily manifests as cardiomyopathy while ATTR due to a genetic variant manifests as cardiomyopathy and/or polyneuropathy. Approximately 50 000 to 150 000 people in the US have heart failure due to ATTR amyloidosis. Without treatment, heart failure due to ATTR amyloidosis is associated with a median survival of approximately 5 years. More than 130 different inherited genetic variants in TTR exist. The most common genetic variant is Val122Ile (pV142I), an allele with an origin in West African countries, that is present in 3.4% of African American individuals in the US or approximately 1.5 million persons. The diagnosis can be made using serum free light chain assay and immunofixation electrophoresis to exclude light chain amyloidosis combined with cardiac nuclear scintigraphy to detect radiotracer uptake in a pattern consistent with amyloidosis. Loop diuretics, such as furosemide, torsemide, and bumetanide, are the primary treatment for fluid overload and symptomatic relief of patients with ATTR heart failure. An ATTR-directed therapy that inhibited misfolding of the TTR protein (tafamidis, a protein stabilizer), compared with placebo, reduced mortality from 42.9% to 29.5%, reduced hospitalizations from 0.7/year to 0.48/year, and was most effective when administered early in disease course.

Conclusions and Relevance

ATTR amyloidosis causes cardiomyopathy in up to approximately 150 000 people in the US and tafamidis is the only currently approved therapy. Tafamidis slowed progression of ATTR amyloidosis and improved survival and prevented hospitalization, compared with placebo, in people with ATTR-associated cardiomyopathy.

Detection of TTR Amyloid in the Conjunctiva Using a Novel Fluorescent Ocular Tracer

Background

Transthyretin amyloidosis (ATTR) is a significant cause of cardiomyopathy and other morbidities in the elderly and Black Americans. ATTR can be treated with new disease-modifying therapies, but large shortfalls exist in its diagnosis. The objective of this study was to test whether TTR amyloid can be detected and imaged in the conjunctiva using a novel small-molecule fluorescent ocular tracer, with the implication that ATTR might be diagnosable by a simple eye examination.

Methods

Three approaches were used in this study. First, AMDX-9101 was incubated with in vitro aggregated TTR protein, and changes in its excitation and emission spectra were quantified. Second, a cadaver eye from a patient with familial amyloid polyneuropathy type II TTR mutation and a vitrectomy sample from an hATTR patient were incubated with AMDX-9101 and counterstained with Congo Red and antibodies to TTR to determine whether AMDX-9101 labels disease-related TTR amyloid deposits in human conjunctiva and eye. Last, imaging of in vitro aggregated TTR amyloid labeled with AMDX-9101 was tested in a porcine ex vivo model, using a widely available clinical ophthalmic imaging device.

Results

AMDX-9101 hyper-fluoresced in the presence of TTR amyloid in vitro, labeled TTR amyloid deposits in postmortem human conjunctiva and other ocular tissues and could be detected under the conjunctiva of a porcine eye using commercially available ophthalmic imaging equipment.

Conclusions

AMDX-9101 enabled detection of TTR amyloid in the conjunctiva, and the fluorescent binding signal can be visualized using commercially available ophthalmic imaging equipment.

Translational Relevance

AMDX-9101 detection of TTR amyloid may provide a potential new and noninvasive test for ATTR that could lead to earlier ATTR diagnosis, as well as facilitate development of new therapeutics.

Deep phenotyping of p.(V142I)-associated variant transthyretin amyloid cardiomyopathy: Distinct from wild-type transthyretin amyloidosis?

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an increasingly recognized cause of heart failure. A total of 3-4% of individuals of African descent carry a TTR gene mutation encoding the p.(V142I) variant, a powerful risk factor for development of variant ATTR-CM (ATTRv-CM); this equates to 1.6 million carriers in the United States. We undertook deep phenotyping of p.(V142I)-ATTRv-CM and comparison with wild-type ATTR-CM (ATTRwt-CM).

METHODS AND RESULTS

A retrospective study of 413 patients with p.(V142I) ATTRv-CM who attended the UK National Amyloidosis Centre (NAC) was conducted. Patients underwent evaluation at time of diagnosis, including clinical, echocardiography, and biomarker analysis; a subgroup had cardiac magnetic resonance (CMR) imaging. A total of 413 patients with ATTRwt-CM, matched for independent predictors of prognosis (age, NAC Stage, decade of first presentation), were used as a comparator group. At time of diagnosis, patients with ATTRv-CM had significant functional impairment by New York Heart Association classification (NHYA class ≥ III; 38%) and 6-min walk test distance (median 276 m). Median 5-year survival in ATTRv-CM patients was 31 versus 59 months in matched patients with ATTRwt-CM (p < 0.001). Patients with ATTRv-CM had significant impairment of functional parameters by echocardiography including biventricular impairment, high burden of regurgitant valvular disease and low cardiac output. Multivariable analysis revealed the prognostic importance of right ventricular dysfunction. CMR and histological analysis revealed myocyte atrophy and widespread myocardial infiltration in ATTRv-CM.

CONCLUSION

p.(V142I)-ATTRv-CM has an aggressive phenotype characterized by myocyte loss and widespread myocardial infiltration which may account for frequent biventricular failure and poor prognosis in this ATTR-CM genotypic subgroup.

The impact of damaging epilepsy and cardiac genetic variant burden in sudden death in the young

BACKGROUND

Sudden unexpected death in children is a tragic event. Understanding the genetics of sudden death in the young (SDY) enables family counseling and cascade screening. The objective of this study was to characterize genetic variation in an SDY cohort using whole genome sequencing.

METHODS

The SDY Case Registry is a National Institutes of Health/Centers for Disease Control and Prevention surveillance effort to discern the prevalence, causes, and risk factors for SDY. The SDY Case Registry prospectively collected clinical data and DNA biospecimens from SDY cases < 20 years of age. SDY cases were collected from medical examiner and coroner offices spanning 13 US jurisdictions from 2015 to 2019. The cohort included 211 children (median age 0.33 year; range 0-20 years), determined to have died suddenly and unexpectedly and from whom DNA biospecimens for DNA extractions and next-of-kin consent were ascertained. A control cohort consisted of 211 randomly sampled, sex- and ancestry-matched individuals from the 1000 Genomes Project. Genetic variation was evaluated in epilepsy, cardiomyopathy, and arrhythmia genes in the SDY and control cohorts. American College of Medical Genetics/Genomics guidelines were used to classify variants as pathogenic or likely pathogenic. Additionally, pathogenic and likely pathogenic genetic variation was identified using a Bayesian-based artificial intelligence (AI) tool.

RESULTS

The SDY cohort was 43% European, 29% African, 3% Asian, 16% Hispanic, and 9% with mixed ancestries and 39% female. Six percent of the cohort was found to harbor a pathogenic or likely pathogenic genetic variant in an epilepsy, cardiomyopathy, or arrhythmia gene. The genomes of SDY cases, but not controls, were enriched for rare, potentially damaging variants in epilepsy, cardiomyopathy, and arrhythmia-related genes. A greater number of rare epilepsy genetic variants correlated with younger age at death.

CONCLUSIONS

While damaging cardiomyopathy and arrhythmia genes are recognized contributors to SDY, we also observed an enrichment in epilepsy-related genes in the SDY cohort and a correlation between rare epilepsy variation and younger age at death. These findings emphasize the importance of considering epilepsy genes when evaluating SDY.

Advances in the diagnosis and treatment of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underrecognized cause of heart failure (HF). ATTR-CM can lead to a number of cardiovascular manifestations including HF, rhythm disturbances, and valvular disease that ultimately limit quality of life and prognosis. Due to advances in diagnostic modalities and therapeutic options, the prevalence of ATTR-CM is rising. There are several classes of medications under active investigation, though most therapies are most efficacious if instituted early on in the disease course. As such, early clinical recognition and prompt diagnosis are crucial to improving disease related outcomes. In this review, we highlight clinical manifestations of ATTR-CM as well as contemporary diagnostic and treatment approaches to the disease.

Genomic Engineering of Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Recent advances in patient-derived induced Pluripotent Stem Cell (iPSC) generation, improvement of cardiomyocyte-directed differentiation protocols, and the availability of new genome editing techniques have opened up new avenues for disease modeling of cardiomyopathies. Patients with cardiomyopathies often harbor a single-base substitution believed to be linked to the disease phenotype. Somatic cells derived from patients can be efficiently reprogrammed into iPSCs and subsequently engineered. The targeting of a precise mutation can be achieved by the introduction of double stranded breaks with CRISPR-Cas9 and by homology-directed repair when using a DNA donor template. This allows for the correction of a mutation in a patient iPSC line to generate an isogenic control. In addition, key mutations associated with cardiomyopathies can be introduced in an iPSC line derived from a healthy individual using the same techniques. In this chapter, we describe in detail how to engineer pluripotent stem cells to model cardiomyopathy in a dish using CRISPR-Cas9 technology.

A deep learning transformer model predicts high rates of undiagnosed rare disease in large electronic health systems

It is estimated that as many as 1 in 16 people worldwide suffer from rare diseases. Rare disease patients face difficulty finding diagnosis and treatment for their conditions, including long diagnostic odysseys, multiple incorrect diagnoses, and unavailable or prohibitively expensive treatments. As a result, it is likely that large electronic health record (EHR) systems include high numbers of participants suffering from undiagnosed rare disease. While this has been shown in detail for specific diseases, these studies are expensive and time consuming and have only been feasible to perform for a handful of the thousands of known rare diseases. The bulk of these undiagnosed cases are effectively hidden, with no straightforward way to differentiate them from healthy controls. The ability to access them at scale would enormously expand our capacity to study and develop drugs for rare diseases, adding to tools aimed at increasing availability of study cohorts for rare disease. In this study, we train a deep learning transformer algorithm, RarePT (Rare-Phenotype Prediction Transformer), to impute undiagnosed rare disease from EHR diagnosis codes in 436,407 participants in the UK Biobank and validated on an independent cohort from 3,333,560 individuals from the Mount Sinai Health System. We applied our model to 155 rare diagnosis codes with fewer than 250 cases each in the UK Biobank and predicted participants with elevated risk for each diagnosis, with the number of participants predicted to be at risk ranging from 85 to 22,000 for different diagnoses. These risk predictions are significantly associated with increased mortality for 65% of diagnoses, with disease burden expressed as disability-adjusted life years (DALY) for 73% of diagnoses, and with 72% of available disease-specific diagnostic tests. They are also highly enriched for known rare diagnoses in patients not included in the training set, with an odds ratio (OR) of 48.0 in cross-validation cohorts of the UK Biobank and an OR of 30.6 in the independent Mount Sinai Health System cohort. Most importantly, RarePT successfully screens for undiagnosed patients in 32 rare diseases with available diagnostic tests in the UK Biobank. Using the trained model to estimate the prevalence of undiagnosed disease in the UK Biobank for these 32 rare phenotypes, we find that at least 50% of patients remain undiagnosed for 20 of 32 diseases. These estimates provide empirical evidence of a high prevalence of undiagnosed rare disease, as well as demonstrating the enormous potential benefit of using RarePT to screen for undiagnosed rare disease patients in large electronic health systems.

Comparison of cardiac involvement, extracardiac manifestations and outcomes between homozygote and heterozygote transthyretin p.Val142Ile (V122I) variant in patients with hereditary transthyretin amyloidosis: a cohort study

BACKGROUND

Hereditary transthyretin (ATTRv) p.Val142Ile (V122I) mutation is the most common inherited cause of cardiac amyloidosis and little is known about the phenotype and outcome of the rare homozygotic genotype. This study aimed to compare phenotypic characteristics and outcomes between heterozygous and homozygous patients with ATTRv V122I amyloidosis.

MATERIAL AND METHODS

This monocentric, observational, retrospective study conducted at the French National Referral Centre for Cardiac Amyloidosis (Henri Mondor Hospital, Créteil), described clinical, electrocardiographic, cardiac imaging features and prognostic data for patients with ATTRv V122I amyloidosis.

RESULTS

Among 185 ATTRv V122I patients identified, 161 were heterozygous and 24 were homozygous. The homozygous frequency was 13%. Onset occured significantly earlier in the homozygotes compared to heterozygotes with earlier median age at diagnosis (67[63-71] years vs 76[70-79] years, p < .001), age at first cardiac symptom (66[61-71] years vs 74[68-78] years, p < .001) and age at first extracardiac symptom (59[52-70] years vs 69[62-75] years, p = .003). Homozygous ATTRv V122I was also associated with greater disease burden with earlier events (death, transplant or hospitalisation for acute heart failure) compared with heterozygotes (71[67-74] vs 78[76-79] years, p = .018).

CONCLUSION

This rare, homozygous V122I cohort confirmed the earlier age of onset, death and cardiac events in this population.

Stigma manifestations in cardiomyopathy care impact outcomes for black patients: a qualitative study

INTRODUCTION

Inequities in clinical care may contribute to racial disparities observed in studies of heart disease morbidity and cardiogenetic testing outcomes. There is a lack of research aimed at understanding the complexity of those inequities, but stigma likely contributes. This qualitative exploratory study helps close that gap in the literature by describing intersectional stigma manifestations perceived by the Black cardiomyopathy patient population at one academic medical center.

METHODS

Qualitative interviews were conducted with 14 Black cardiomyopathy patients. Interviews aimed to elicit patients' experiences with discrimination related to diagnosis, symptoms, genetic testing, knowledge of genetic results, genetic counseling, providers' actions, and providers' communication. The interview guide was informed by The Health Stigma and Discrimination Framework. Data were also collected about participant demographics, type of cardiomyopathy, age of diagnosis, documentation of relevant family history, and completion of genetic counseling and/or genetic testing.

RESULTS

More than half of participants reported intersectional stigma manifestations related to their race, age, and/or weight while receiving care from cardiologists, nurse practitioners, genetic counselors, or clinical support staff. Stigma manifestations included physical roughness during patient care, withholding diagnostically-relevant information from the patient, impersonal care, coercion, and use of offensive stereotyped language by providers. These stigma manifestations impacted access to care, uptake of genetic testing, timeline to diagnosis, patient emotion, patient-provider trust, and adherence to medical recommendations.

CONCLUSIONS

This study provides nuanced qualitative descriptions of stigma manifestations that affect patient and clinical outcomes in cardiology care and genetic services in one medical center in the Southeastern United States. The results of this study suggest that provider bias and stigma manifestations have an adverse effect on cardiogenetic and clinical outcomes among Black cardiomyopathy patients. Clinical interventions are suggested to assist health professionals in providing culturally-competent and respectful care. These results help inform patient-provider communication, clinical policies, and evidence-based practice in cardiology care and genetics. Continued study of this topic across more institutions and with a larger sample size is needed to confirm the generalizability of the conclusions.

Cardiovascular Disease and Mortality in Black Women Carrying the Amyloidogenic V122I Transthyretin Gene Variant

BACKGROUND

Long-term data on cardiovascular disease (CVD) and mortality in female carriers of the transthyretin (TTR) V122I (pV142I) variant, one of the most common variants of hereditary transthyretin cardiac amyloidosis, are sparse and the effects of blood pressure, heart rate, body mass index, and physical activity on CVD outcomes remain largely unknown.

OBJECTIVES

The aim was to first examine the relationship of TTR V122I (pV142I) carrier status with CVD and mortality and second to investigate the effects of blood pressure, heart rate, body mass index, and physical activity in a large cohort of postmenopausal women.

METHODS

The study population consisted of 9,862 non-Hispanic Black/African American women, 9,529 noncarriers and 333 TTR V122I carriers, enrolled in the Women's Health Initiative at 40 centers in the United States. Women were generally healthy and postmenopausal at the time of enrollment (1993-1998). CVD was defined as a composite endpoint consisting of coronary heart disease, stroke, acute heart failure or CVD death, and all-cause mortality. CVD cases were based on self-reported annual mailed health updates. All information was centrally adjudicated by trained physicians. HRs and 95% CIs were obtained from adjusted Cox proportional hazards models.

RESULTS

Among 9,862 Black female participants (mean age: 62 years [IQR: 56-67 years]), the population frequency of the TTR V122I variant was 3.4% (333 variant carriers and 9,529 noncarriers). During a mean follow-up of 16.1 years (IQR: 9.7-22.2 years), incident CVD occurred in 2,229 noncarriers and 96 carriers, whereas 2,689 noncarriers and 108 carriers died. In adjusted models including demographic, lifestyle, and medical history covariates, TTR V122I carriers were at higher risk of the composite endpoint CVD (HR: 1.52; 95% CI: 1.22-1.88), acute heart failure (HR: 2.21; 95% CI: 1.53-3.18), coronary heart disease (HR: 1.80; 95% CI: 1.30-2.47), CVD death (HR: 1.70; 95% CI: 1.26-2.30), and all-cause mortality (HR: 1.28; 95% CI: 1.04-1.56). The authors found a significant interaction by age but not by blood pressure, heart rate, body mass index, or physical activity.

CONCLUSIONS

Black female TTR V122I (pV142I) carriers have a higher CVD and all-cause mortality risk compared to noncarriers. In case of clinical suspicion of amyloidosis, they should be screened for TTR V122I (pV142I) carrier status to ensure early treatment onset.

Clinical Penetrance of the Transthyretin V122I Variant in Older Black Patients With Heart Failure: The SCAN-MP (Screening for Cardiac Amyloidosis With Nuclear Imaging in Minority Populations) Study

Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed cause of heart failure (HF) among patients ≥60 years of age. Although the V122I (valine to isoleucine substitution at position 122 of the transthyretin protein) variant associated with hereditary ATTR-CM is present in 3.4% of self-identified Black individuals in the United States (or 1.5 million people), the phenotypic penetrance is not known. Methods and Results The SCAN-MP (Screening for Cardiac Amyloidosis With Nuclear Imaging in Minority Populations) study is a currently accruing prospective multisite study designed to determine the prevalence of ATTR-CM using technetium-99m-pyrophosphate imaging in older (≥60 years of age) self-identified Black and Hispanic individuals with HF. Calculations of the penetrance and prevalence of the V122I allele, along with analyses of functional, biochemical, and echocardiographic parameters, were performed for the first 278 Black participants in SCAN-MP. The prevalence of ATTR-CM was 6.8% (95% CI, 4.2-10.5; n=19 cases), of whom 63% were ATTR wild-type. The prevalence of V122I was 6.5% (n=18 carriers), of whom 7 had ATTR-CM, yielding a phenotypic penetrance of 39% (95% CI, 17-64). V122I carriers with ATTR-CM evidenced more advanced HF than carriers without ATTR-CM. Prealbumin concentration was lowest among V122I carriers with ATTR-CM (12.9 mg/dL) versus carriers without ATTR-CM (21.0 mg/dL) and HF controls (25.0 mg/dL, P<0.0001). Conclusions Among older Black individuals with HF and increased left ventricular wall thickness, of those with ATTR-CM, 63% had wild-type, and of those with V122I, the phenotypic penetrance of ATTR-CM was 39% (95% CI, 17-64), suggesting that genotype alone is insufficient for diagnosis. Prealbumin concentration may be useful to identify V122I carriers with ATTR-CM. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03812172.

Age Dependency of Cardiovascular Outcomes With the Amyloidogenic pV142I Transthyretin Variant Among Black Individuals in the US

Importance

Hereditary transthyretin cardiac amyloidosis is an increasingly recognized cause of heart failure (HF) with distinct treatment. The amyloidogenic pV142I (V122I) variant is present in 3% to 4% of Black individuals in the US and increases the risk for atrial fibrillation (AF), HF, and mortality. Since hereditary transthyretin cardiac amyloidosis demonstrates age-dependent anatomic penetrance, evaluation later in life may identify survivors at particularly high risk.

Objective

To estimate age-dependent risks for cardiovascular events with the variant.

Design, Settings, and Participants

This cohort study analyzed Black participants from the Atherosclerosis Risk in Communities (ARIC) study attending visit 1 (1987-1989) (followed up until 2019; median follow-up, 27.6 years). Data analyses were completed from June 2022 to April 2023.

Exposure

pV142I carrier status.

Main outcomes

The association between the variant and AF, HF hospitalization, mortality, and a composite of HF hospitalization or mortality was modeled by generating 10-year absolute risk differences for each year between ages 53 (the median age at visit 1) and 80 years, adjusting for the first 5 principal components of ancestry and sex. As an example, 5- and 10-year risk differences were specifically estimated for the composite outcome among participants surviving to age 80 years.

Results

Among 3856 Black participants (including 124 carriers) at visit 1, 2403 (62%) were women, 2140 (56%) had hypertension, and 740 (20%) had diabetes, with no differences between groups. The 10-year absolute risk difference between ages 53 and 80 years increased over time for each outcome. Statistical significance for increased 10-year risk difference emerged near ages 65 years for AF, 70 years for HF hospitalization, and 75 years for mortality. Among participants surviving to age 80 years, carriers had a 20% (95% CI, 2%-37%) and 24% (95% CI, 1%-47%) absolute increased risk for HF hospitalization or death at 5 and 10 years, respectively. Thus, at age 80 years, only 4 carriers would need to be identified to attribute 1 HF hospitalization or death over the following decade to the variant.

Conclusions and Relevance

In this study, age-specific risks were provided for relevant outcomes with the pV142I variant. Despite a relatively benign course during earlier years, Black individuals who carry the pV142I variant surviving into later life may be particularly vulnerable. These data may inform timing for screening, risk counseling to patients, and potential strategies for early targeted therapy.

Disease risk and healthcare utilization among ancestrally diverse groups in the Los Angeles region

An individual's disease risk is affected by the populations that they belong to, due to shared genetics and environmental factors. The study of fine-scale populations in clinical care is important for identifying and reducing health disparities and for developing personalized interventions. To assess patterns of clinical diagnoses and healthcare utilization by fine-scale populations, we leveraged genetic data and electronic medical records from 35,968 patients as part of the UCLA ATLAS Community Health Initiative. We defined clusters of individuals using identity by descent, a form of genetic relatedness that utilizes shared genomic segments arising due to a common ancestor. In total, we identified 376 clusters, including clusters with patients of Afro-Caribbean, Puerto Rican, Lebanese Christian, Iranian Jewish and Gujarati ancestry. Our analysis uncovered 1,218 significant associations between disease diagnoses and clusters and 124 significant associations with specialty visits. We also examined the distribution of pathogenic alleles and found 189 significant alleles at elevated frequency in particular clusters, including many that are not regularly included in population screening efforts. Overall, this work progresses the understanding of health in understudied communities and can provide the foundation for further study into health inequities.

Evaluation of the Performance of the RECODe Equation with the Addition of Polygenic Risk Scores for Adverse Cardiovascular Outcomes in Individuals with Type II Diabetes

Aims/Hypothesis

Individuals with T2D are at an increased risk of developing cardiovascular complications; early identification of individuals can lead to an alteration of the natural history of the disease. Current approaches to risk prediction tailored to individuals with T2D are exemplified by the RECODe algorithms which predict CVD outcomes among individuals with T2D. Recent efforts to improve CVD risk prediction among the general population have included the incorporation of polygenic risk scores (PRS). This paper aims to investigate the utility of the addition of a coronary artery disease (CAD), stroke and heart failure risk score to the current RECODe model for disease stratification.

Methods

We derived PRS using summary statistics for ischemic stroke (IS) from the coronary artery disease (CAD) and heart failure (HF) and tested prediction accuracy in the Penn Medicine Biobank (PMBB). A Cox proportional hazards model was used for time-to-event analyses within our cohort, and we compared model discrimination for the RECODe model with and without a PRS using AUC.

Results

The RECODe model alone demonstrated an AUC [95% CI] of 0.67 [0.62-0.72] for ASCVD; the addition of the three PRS to the model demonstrated an AUC [95% CI] of 0.66 [0.63-0.70]. A z-test to compare the AUCs of the two models did not demonstrate a detectable difference between the two models (p=0.97).

Conclusions/Interpretation

In the present study, we demonstrate that although PRS associate with CVD outcomes independent of traditional risk factors among individuals with T2D, the addition of PRS to contemporary clinical risk models does not specifically improve the predictive performance as compared to the baseline model.

Design and Rationale the SCAN-MP (Screening for Cardiac Amyloidosis With Nuclear Imaging in Minority Populations) Study

Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is an important cause of heart failure in older individuals. Misfolding and deposition of transthyretin or prealbumin protein causes ATTR-CM in the context of a normal (wild-type) or variant TTR sequence. Variant ATTR-CM is most commonly caused by the substitution of valine for isoleucine at position 122 in transthyretin (Val122Ile or pV142I, almost exclusively observed in individuals of West African ancestry), demonstrated in 3.4% of self-identified Black individuals in the United States with an estimated 1.5 million carriers. Despite the large number of known pV142I carriers, the proportion of older Black patients with heart failure attributable to ATTR-CM remains unknown. Methods To address this knowledge gap, the SCAN-MP (Screening for Cardiac Amyloidosis with Nuclear Imaging in Minority Populations) study was funded by the National Institutes of Health/National Heart, Lung, and Blood Institute (R01HL139671) to enroll a targeted population of self-identified, community-dwelling Black or Caribbean Hispanic patients (many of whom are of West African ancestry) >60 years of age with heart failure and identify ATTR-CM by noninvasive nuclear imaging. The principal objective of SCAN-MP is to determine the prevalence of ATTR-CM in this population. Secondary objectives will explore TTR genotype, demographics, progression of variant versus wild-type ATTR-CM, and biochemical mechanisms of transthyretin amyloid fibril formation. Conclusions The SCAN-MP study is the largest, prospective study of cardiac amyloidosis in Black and Hispanic individuals. Both wild-type and variant ATTR-CM are now treatable with the US Food and Drug-approved drug tafamidis. The insights gained from SCAN-MP are likely to improve those at risk for or afflicted with ATTR-CM. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03812172.

Cardiac Amyloidosis

Amyloidosis is a pathologic and clinical condition resulting from the accumulation of insoluble aggregates of misfolded proteins in tissues. Extracellular deposition of amyloid fibrils in the myocardium leads to cardiac amyloidosis, which is often overlooked as a cause of diastolic heart failure. Although cardiac amyloidosis was previously believed to have a poor prognosis, recent advances in diagnosis and treatment have emphasized the importance of early recognition and changed management of this condition. This article provides an overview of cardiac amyloidosis and summarizes current screening, diagnosis, evaluation, and treatment options.

When is the best time to screen and evaluate for treatable genetic disorders?: A lifespan perspective

This paper focuses on the question of, "When is the best time to identify an individual at risk for a treatable genetic condition?" In this review, we describe a framework for considering the optimal timing for pursuing genetic and genomic screening for treatable genetic conditions incorporating a lifespan approach. Utilizing the concept of a carousel that represents the four broad time periods when critical decisions might be made around genetic diagnoses during a person's lifetime, we describe genetic testing during the prenatal period, the newborn period, childhood, and adulthood. For each of these periods, we describe the objectives of genetic testing, the current status of screening or testing, the near-term vision for the future of genomic testing, the advantages and disadvantages of each approach, and the feasibility and ethical considerations of testing and treating. The notion of a "Genomics Passbook" is one where an early genomic screening evaluation could be performed on each individual through a public health program, with that data ultimately serving as a "living document" that could be queried and/or reanalyzed at prescribed times during the lifetime of that person, or in response to concerns about symptoms of a genetic disorder in that individual.

Identification of a novel transthyretin mutation D39Y in a cardiac amyloidosis patient and its biochemical characterizations

Hereditary transthyretin cardiac amyloidosis (hATTR-CA) is a rare autosomal dominantly inherited disease caused by mutations in the transthyretin (TTR) gene. TTR mutations often cause the instability of transthyretin, production of misfolded proteins, and ultimately excessive deposition of insoluble amyloid fibrils in the myocardium, thereby leading to cardiac dysfunction. Herein, we report a novel transthyretin D39Y mutation in a Chinese family. We characterized the kinetic and thermodynamic stabilities of D39Y mutant TTR, revealing that TTR D39Y mutant was less stable than WT TTR and more stable than amyloidogenic mutation TTR L55P. Meanwhile, the only FDA approved drug Tafamidis showed satisfactory inhibitory effect toward ATTR amyloid formation and strong binding affinity in test tube revealed by isothermal titration calorimetry. Finally, we measured the well-folded tetrameric TTR concentration in patient's and his descents' blood serum using a previously reported UPLC-based assay. Notably, the tetramer concentrations gradually increased from symptomatic D39Y gene carrier father, to asymptomatic D39Y gene carrier daughter, and further to wild type daughter, suggesting the decrease in functional tetrameric TTR concentration may serve as an indicator for disease age of onset in D39Y gene carriers. The study described a Chinese family with hATTR-CA due to the TTR variant D39Y with its destabilizing effect in both kinetic and thermodynamic stabilities.

Elective genomic testing: Practice resource of the National Society of Genetic Counselors

Genetic counseling for patients who are pursuing genetic testing in the absence of a medical indication, referred to as elective genomic testing (EGT), is becoming more common. This type of testing has the potential to detect genetic conditions before there is a significant health impact permitting earlier management and/or treatment. Pre- and post-test counseling for EGT is similar to indication-based genetic testing. Both require a complete family and medical history when ordering a test or interpreting a result. However, EGT counseling has some special considerations including greater uncertainties around penetrance and clinical utility and a lack of published guidelines. While certain considerations in the selection of a high-quality genetic testing laboratory are universal, there are some considerations that are unique to the selection of a laboratory performing EGT. This practice resource intends to provide guidance for genetic counselors and other healthcare providers caring for adults seeking pre- or post-test counseling for EGT. Genetic counselors and other genetics trained healthcare providers are the ideal medical professionals to supply accurate information to individuals seeking counseling about EGT enabling them to make informed decisions about testing and follow-up.

Counseling Family Members and Monitoring for Evidence of Disease in Asymptomatic Carriers of Amyloid Transthyretin Cardiac Amyloidosis

Transthyretin (TTR), a plasma transport protein produced in the liver, is prone to misfolding, leading to the deposition of amyloid fibrils and progressive dysfunction of cardiac and nervous system tissues, a condition known as amyloid TTR (ATTR) amyloidosis. More than 140 different pathogenic variants in TTR have been documented, most of which cause hereditary forms of ATTR amyloidosis. The most common mutations, traditionally known as Val30Met, Val122Ile, and Thr60Ala, lead to predominantly sensory, motor, and autonomic neuropathies, cardiomyopathy, and mixed presentations, respectively, although each mutation may cause symptoms across the neurologic and cardiac spectrum. Val30Met is endemic to Brazil, Japan, Portugal, and Sweden. The Val122Ile variant is present in 3.4% of people with West African ancestry, whereas Thr60Ala originated in northwestern Ireland and spread to the rest of the United Kingdom, the United States, and elsewhere. Val30Met and Thr60Ala tend to have more aggressive clinical presentations at younger ages, whereas Val122Ile predominantly affects older Black men. Due to similarities with hypertrophic cardiomyopathy, heart failure with preserved ejection fraction, and other overlapping conditions, ATTR cardiomyopathy is often under recognized and underdiagnosed, especially in Val122Ile carriers. Understanding these carrier populations and differences in ATTR amyloidosis characteristics associated with each variant is essential for appropriate diagnosis and genetic counseling of affected patients and their relatives.

The Penn Medicine BioBank: Towards a Genomics-Enabled Learning Healthcare System to Accelerate Precision Medicine in a Diverse Population

The Penn Medicine BioBank (PMBB) is an electronic health record (EHR)-linked biobank at the University of Pennsylvania (Penn Medicine). A large variety of health-related information, ranging from diagnosis codes to laboratory measurements, imaging data and lifestyle information, is integrated with genomic and biomarker data in the PMBB to facilitate discoveries and translational science. To date, 174,712 participants have been enrolled into the PMBB, including approximately 30% of participants of non-European ancestry, making it one of the most diverse medical biobanks. There is a median of seven years of longitudinal data in the EHR available on participants, who also consent to permission to recontact. Herein, we describe the operations and infrastructure of the PMBB, summarize the phenotypic architecture of the enrolled participants, and use body mass index (BMI) as a proof-of-concept quantitative phenotype for PheWAS, LabWAS, and GWAS. The major representation of African-American participants in the PMBB addresses the essential need to expand the diversity in genetic and translational research. There is a critical need for a "medical biobank consortium" to facilitate replication, increase power for rare phenotypes and variants, and promote harmonized collaboration to optimize the potential for biological discovery and precision medicine.

Prevalence and Clinical Outcomes of Transthyretin Amyloidosis: A Systematic Review and Meta-analysis

BACKGROUND

Systematic evidence on the prevalence and clinical outcome of transthyretin amyloidosis (ATTR) is missing. We explored: a) the prevalence of cardiac amyloidosis in various patient subgroups, b) survival estimates for ATTR subtypes and c) the effects of novel therapeutics on the natural course of disease.

METHODS

A systematic review of literature published in Medline before 31/12/2021 was performed for the prevalence of cardiac amyloidosis & all-cause mortality of ATTR patients. Extracted data included sample size, age, sex, and all-cause mortality at 1, 2 and 5-years. Subgroup analyses were performed for ATTR subtype i.e., wild type ATTR (wtATTR) vs. hereditary ATTR (htATTR), htATTR genotypes and treatment subgroups.

RESULTS

We identified a total of 62 studies (n=277,882 individuals) reporting the prevalence of cardiac amyloidosis, which was high among patients with a hypertrophic cardiomyopathy phenotype, HFpEF, and elderly with aortic stenosis. Data on ATTR mortality were extracted from 95 studies (n=18,238 ATTR patients). Patients with wtATTR were older (p=7x10^-10 ) and more frequently male (p=5x10^-20 ) vs. htATTR. The 2-year survival of ATTR was 73.3% (95%CI 71.6-76.2); for non-subtyped ATTR 70.4% (95%CI 66.9-73.9), for wtATTR (76.0%, 95%CI: 73.0-78.9) and for htATTR (77.2%, 95%CI: 74.0-80.4); in meta-regression analysis wtATTR was associated with higher survival after adjusting for confounders. There was an interaction between survival and htATTR genotypes (p=10^-15 , Val30Met having the lowest and Val122Ile/Thr60Ala the highest mortality). ATTR 2-year survival was higher on tafamidis/patisiran compared to natural disease course (79.9%, 95%CI: 74.4-85.3 vs. 72.4%, 95%CI 69.8-74.9, p<0.05).

CONCLUSIONS

We report the prevalence of ATTR in various population subgroups and provide survival estimates for the natural course of disease and the effects of novel therapeutics. Important gaps in worldwide epidemiology research in ATTR were identified. This article is protected by copyright. All rights reserved.

Addressing the routine failure to clinically identify monogenic cases of common disease

Changes in medical practice are needed to improve the diagnosis of monogenic forms of selected common diseases. This article seeks to focus attention on the need for universal genetic testing in common diseases for which the recommended clinical management of patients with specific monogenic forms of disease diverges from standard management and has evidence for improved outcomes.We review evidence from genomic screening of large patient cohorts, which has confirmed that important monogenic case identification failures are commonplace in routine clinical care. These case identification failures constitute diagnostic misattributions, where the care of individuals with monogenic disease defaults to the treatment plan offered to those with polygenic or non-genetic forms of the disease.The number of identifiable and actionable monogenic forms of common diseases is increasing with time. Here, we provide six examples of common diseases for which universal genetic test implementation would drive improved care. We examine the evidence to support genetic testing for common diseases, and discuss barriers to widespread implementation. Finally, we propose recommendations for changes to genetic testing and care delivery aimed at reducing diagnostic misattributions, to serve as a starting point for further evaluation and development of evidence-based guidelines for implementation.

Association of Transthyretin Val122Ile Variant With Incident Heart Failure Among Black Individuals

Importance

A genetic variant in the TTR gene (rs76992529; Val122Ile), present more commonly in individuals with African ancestry (population frequency: 3%-4%), causes misfolding of the tetrameric transthyretin protein complex that accumulates as extracellular amyloid fibrils and results in hereditary transthyretin amyloidosis.

Objective

To estimate the association of the amyloidogenic Val122Ile TTR variant with the risk of heart failure and mortality in a large, geographically diverse cohort of Black individuals.

Design, Setting, and Participants

Retrospective population-based cohort study of 7514 self-identified Black individuals living in the US participating in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study with genetic data available and without heart failure at baseline. The participants were enrolled at the baseline visit (2003-2007). The end of follow-up for the majority of outcomes was on December 31, 2018. All-cause mortality data were available through December 31, 2020.

Exposures

TTR Val122Ile (rs76992529) genotype.

Main Outcome and Measures

The primary outcome was incident heart failure (first hospitalization for heart failure or death due to heart failure). The secondary outcomes were heart failure mortality, cardiovascular mortality, and all-cause mortality. The multivariable Cox proportional hazards regression analyses were adjusted for genetic ancestry and demographic, clinical, and social factors.

Results

Among 7514 Black participants (median age, 64 years [IQR, 57-70 years]; 61% women), the population frequency of the TTR Val122Ile variant was 3.1% (232 variant carriers and 7282 noncarriers). During a median follow-up of 11.1 years (IQR, 5.9-13.5 years), incident heart failure occurred in 535 individuals (34 variant carriers and 501 noncarriers) and the incidence of heart failure was 15.64 per 1000 person-years among variant carriers vs 7.16 per 1000 person-years among noncarriers (adjusted hazard ratio [HR], 2.43 [95% CI, 1.71-3.46]; P < .001). Deaths due to heart failure occurred in 141 individuals (13 variant carriers and 128 noncarriers) and the incidence of heart failure mortality was 6.11 per 1000 person-years among variant carriers vs 1.85 per 1000 person-years among noncarriers (adjusted HR, 4.19 [95% CI, 2.33-7.54]; P < .001). Deaths due to cardiovascular causes occurred in 793 individuals (34 variant carriers and 759 noncarriers) and the incidence of cardiovascular death was 15.18 per 1000 person-years among variant carriers vs 10.61 per 1000 person-years among noncarriers (adjusted HR, 1.69 [95% CI, 1.19-2.39]; P = .003). Deaths due to any cause occurred in 2715 individuals (100 variant carriers and 2615 noncarriers) and the incidence of all-cause mortality was 41.46 per 1000 person-years among variant carriers vs 33.94 per 1000 person-years among noncarriers (adjusted HR, 1.46 [95% CI, 1.19-1.78]; P < .001). There was no significant interaction between TTR variant carrier status and sex on incident heart failure and the secondary outcomes.

Conclusions and Relevance

Among a cohort of Black individuals living in the US, being a carrier of the TTR Val122Ile variant was significantly associated with an increased risk of heart failure.

High-avidity binding drives nucleation of amyloidogenic transthyretin monomer

Amyloidosis involves stepwise growth of fibrils assembled from soluble precursors. Transthyretin (TTR) naturally folds into a stable tetramer, whereas conditions and mutations that foster aberrant monomer formations facilitate TTR oligomeric aggregation and subsequent fibril extension. We investigated the early assembly of oligomers by WT TTR compared with its V30M and V122I variants. We monitored time-dependent redistribution among monomer, dimer, tetramer, and oligomer contents in the presence and absence of multimeric TTR seeds. The seeds were artificially constructed recombinant multimers that contained 20–40 TTR subunits via engineered biotin-streptavidin (SA) interactions. As expected, these multimer seeds rapidly nucleated TTR monomers into larger complexes, while having less effect on dimers and tetramers. In vivo, SA-induced multimers formed TTR-like deposits in the heart and the kidney following i.v. injection in mice. While all 3 variants prominently deposited glomerulus in the kidney, only V30M resulted in extensive deposition in the heart. The cardiac TTR deposits varied in size and shape and were localized in the intermyofibrillar space along the capillaries. These results are consistent with the notion of monomeric TTR engaging in high-avidity interactions with tissue amyloids. Our multimeric induction approach provides a model for studying the initiation of TTR deposition in the heart.

Clinical Implications of the Amyloidogenic V122I Transthyretin Variant in the General Population

BACKGROUND

The V122I variant in transthyretin (TTR) is the most common amyloidogenic mutation worldwide. The aim of this study is to describe the cardiac phenotype and risk for adverse cardiovascular outcomes of young V122I TTR carriers in the general population.

METHODS AND RESULTS

TTR genotypes were extracted from whole-exome sequence data in participants of the Dallas Heart Study. Participants with African ancestry, available V122I TTR genotypes (N = 1818) and either cardiac magnetic resonance imaging (n = 1364) or long-term follow-up (n = 1532) were included. The prevalence of V122I TTR carriers (45 ± 10 years) was 3.2% (n/N = 59/1818). The V122I TTR carriers had higher baseline left ventricular wall thickness (8.52 ± 1.82 vs 8.21 ± 1.62 mm, adjusted P = .038) than noncarriers, but no differences in other cardiac magnetic resonance imaging measures (P > .05 for all). Although carrier status was not associated with amino terminal pro-B-type natriuretic peptide (NT-proBNP) at baseline (P = .79), V122I TTR carriers had a greater increase in NT-proBNP on follow-up than noncarriers (median 28.5 pg/mL, interquartile range 11.4-104.1 pg/mL vs median 15.9 pg/mL, interquartile range 0.0-43.0 pg/mL, adjusted P = .018). V122I TTR carriers were at a higher adjusted risk of heart failure (hazard ratio 3.82, 95% confidence interval 1.80-8.13, P < .001), cardiovascular death (hazard ratio 2.65, 95% confidence interval 1.14-6.15, P = .023), and all-cause mortality (hazard ratio 1.95, 95% confidence interval 1.08-3.51, P = .026) in comparison with noncarriers.

CONCLUSIONS

V122I TTR carrier status was associated with a greater increase in NT-proBNP, slightly greater left ventricular wall thickness, and a higher risk for heart failure, cardiovascular death, and all-cause mortality. These findings suggest the need to develop amyloidosis screening strategies for V122I TTR carriers.

Transthyretin: Its function and amyloid formation

Transthyretin (TTR), which is one of the major amyloidogenic proteins in systemic amyloidosis, forms extracellular amyloid deposits in the systemic organs such as nerves, ligaments, heart, and arterioles, and causes two kinds of systemic amyloidosis, hereditary ATTR (ATTRv) amyloidosis induced by variant TTR and aging-related wild-type ATTR (ATTRwt) amyloidosis. More than 150 different mutations, most of which are amyloidogenic, have been reported in the TTR gene. Since most disease-associated mutations affect TTR tetramer dissociation rates, destabilization of TTR tetramers is widely believed to be a critical step in TTR amyloid formation. Recently, effective disease-modifying therapies such as TTR tetramer stabilizers and TTR gene silencing therapies have been developed for ATTR amyloidosis. This study reviews the clinical phenotypes of ATTR amyloidosis, TTR features, and recent progress in promising therapies for ATTR amyloidosis.

Transthyretin V142I Genetic Variant and Cardiac Remodeling, Injury, and Heart Failure Risk in Black Adults

OBJECTIVES

This study evaluated the association of transthyretin (TTR) gene variant, in which isoleucine substitutes for valine at position 122 (V142I), with cardiac structure, function, and heart failure (HF) risk among middle-aged Black adults.

BACKGROUND

The valine-to-isoleucine substitution in the TTR protein is prevalent in Black individuals and causes cardiac amyloidosis.

METHODS

Jackson Heart Study participants without HF at baseline who had available data on the TTR V142I variant were included. The association of the TTR V142I variant with baseline echocardiographic parameters and repeated measures of high-sensitivity cardiac troponin-I (hs-cTnI) was assessed using adjusted linear regression models and linear mixed models, respectively. Adjusted Cox models, restricted mean survival time analysis, and Anderson-Gill models were constructed to determine the association of TTR V142I variant with the risk of incident HF, survival free of HF, and total HF hospitalizations.

RESULTS

A total of 119 of 2,960 participants (4%) were heterozygous carriers of the TTR V142I variant. The TTR V142I variant was not associated with measures of cardiac parameters at baseline but was associated with a greater increase in high-sensitivity troponin I (hs-TnI) levels over time. In adjusted Cox models, TTR V142I variant carriers had significantly higher risk of incident HF (HR: 1.80; 95% CI: 1.07-3.05; P = 0.03), lower survival free of HF (mean difference: 4.0 year; 95% CI: 0.6-6.2 years); P = 0.02), and higher risk of overall HF hospitalizations (HR: 2.12; 95% CI: 1.23-3.63; P = 0.007).

CONCLUSIONS

The TTR V142I variant in middle-aged Black adults is not associated with adverse cardiac remodeling but was associated with a significantly higher burden of chronic myocardial injury, and greater risk of incident HF and overall HF hospitalizations.

Opportunities for Earlier Diagnosis and Treatment of Cardiac Amyloidosis

Despite the rapid expansion of noninvasive (nonbiopsy) diagnosis, contemporary patients with cardiac amyloidosis too often present with advanced features of disease, such as diminished quality of life, elevated natriuretic peptides, and advanced heart failure. Therapeutics for transthyretin cardiomyopathy (ATTR-CM) are most effective when administered before significant symptoms of cardiac dysfunction manifest, making early identification of affected individuals of paramount importance. Community engagement and ensuring that a broad range of clinicians have working knowledge of how to screen for ATTR-CM in everyday practice will be an important step in moving disease identification further upstream. However, reliance on the appropriate and timely diagnosis by individual clinicians may continue to underperform. This review highlights how targeted screening of special populations may facilitate earlier diagnosis. Systems of care that operationalize screening of high-risk subpopulations and prospective validation of novel approaches to ATTR-CM identification are needed.

Hereditary transthyretin-related amyloidosis is frequent in polyneuropathy and cardiomyopathy of no obvious aetiology

BACKGROUND

Hereditary Transthyretin-Related Amyloidosis, a clinically heterogeneous autosomal dominant disease caused by pathogenic variants in the TTR gene, is characterized by the deposition of insoluble misfolded protein fibrils. The diagnosis, especially in non-endemic areas, is typically delayed by 4-5 years; a misdiagnosis due to clinical heterogeneity is common. The study objective was to define the prevalence of Hereditary Transthyretin-Related Amyloidosis in patients with polyneuropathy and/or cardiomyopathy of no obvious aetiology.

METHOD

A multicenter observational "Epidemiological analysis for the hereditary Transthyretin-Related AMyloidosis"-TRAM study was performed in Germany, Austria, and Switzerland.

RESULTS

A total of 5141 participants were recruited by 50 neurologic and 27 cardiologic specialized centres. Genetic analysis demonstrated a 1.1% Hereditary Transthyretin-Related Amyloidosis positivity rate among patients with polyneuropathy and/or cardiomyopathy of not obvious aetiology. Twenty-one various TTR variants (TTR-positive) were identified. Body Mass Index was lower in the TTR-positive patients as an indicator for the involvement of the autonomic nervous system; the age of onset of clinical manifestations was higher in TTR-positive patients. There were no other genotype-phenotype correlations or the prevalence of specific clinical manifestations in TTR-positive patients.

CONCLUSIONS

Our data support the fact that Hereditary Transthyretin-Related Amyloidosis is underdiagnosed in polyneuropathy and cardiomyopathy patients. Routine implementation of genetic testing is recommended in patients with unexplained polyneuropathy and/or cardiomyopathy to accelerate the earlier diagnosis and the time-sensitive treatment initiation.KEY MESSAGESMore than 5.000 participants with CM and/or PNP of no obvious aetiology were recruited in the observational "Epidemiological analysis for the hereditary Transthyretin-Related AMyloidosis" TRAM study and screened for pathogenic TTR variants.The study demonstrated >1% of patients with CM and/or PNP of unclear aetiology are positive for a pathogenic TTR variant.Routine genetic testing is recommended in patients with unexplained CM and/or PNP to accelerate the initial diagnosis and timely treatment initiation.

ATTR Amyloidosis: Current and Emerging Management Strategies: JACC: CardioOncology State-of-the-Art Review

Transthyretin cardiac amyloidosis (ATTR-CA) is increasingly diagnosed owing to the emergence of noninvasive imaging and improved awareness. Clinical penetrance of pathogenic alleles is not complete and therefore there is a large cohort of asymptomatic transthyretin variant carriers. Screening strategies, monitoring, and treatment of subclinical ATTR-CA requires further study. Perhaps the most important translational triumph has been the development of effective therapies that have emerged from a biological understanding of ATTR-CA pathophysiology. These include recently proven strategies of transthyretin protein stabilization and silencing of transthyretin production. Data on neurohormonal blockade in ATTR-CA are limited, with the primary focus of medical therapy on judicious fluid management. Atrial fibrillation is common and requires anticoagulation owing to the propensity for thrombus formation. Although conduction disease and ventricular arrhythmias frequently occur, little is known regarding optimal management. Finally, aortic stenosis and ATTR-CA frequently coexist, and transcatheter valve replacement is the preferred treatment approach.

Using Genomic Techniques in Sports and Exercise Science: Current Status and Future Opportunities

ABSTRACT

The past two decades have built on the successes of the Human Genome Project identifying the impact of genetics and genomics on human traits. Given the importance of exercise in the physical and psychological health of individuals across the lifespan, using genomics to understand the impact of genes in the sports medicine field is an emerging field. Given the complexity of the systems involved, high-throughput genomics is required to understand genetic variants, their functions, and ultimately their effect on the body. Consequently, genomic studies have been performed across several domains of sports medicine with varying degrees of success. While the breadth of these is great, they focus largely on the following three areas: 1) performance; 2) injury susceptibility; and 3) sports associated chronic conditions, such as osteoarthritis. Herein, we review literature on genetics and genomics in sports medicine, offer suggestions to bolster existing studies, and suggest ways to ideally impact clinical care.