Genomic Screening Identifies Individuals at High Risk for Hereditary Transthyretin Amyloidosis

Genomic Screening at a Single Health System

Importance

Completion of the Human Genome Project prompted predictions that genomics would transform medicine, including through genomic screening that identifies potentially medically actionable findings that could prevent disease, detect it earlier, or treat it better. However, genomic screening remains anchored in research and largely unavailable as part of routine care.

Objective

To summarize 11 years of experience with genomic screening and explore the landscape of genomic screening efforts.

Design, Setting, and Participants

This cohort study was based in Geisinger's MyCode Community Health Initiative, a genomic screening program in a rural Pennsylvania health care system in which patient-participants exomes are analyzed.

Main Outcomes and Measures

Genomic screen-positive rates were evaluated and stratified by condition type (cancer, cardiovascular, other) and US Centers for Disease Control and Prevention (CDC) Tier 1 designation. The proportion of participants previously unaware of their genomic result was assessed. Other large-scale population-based genomic screening efforts with genomic results disclosure were compiled from public resources.

Results

A total of 354 957 patients participated in Geisinger's genomic screening program (median [IQR] age, 54 [36-69] years; 194 037 [59.7%] assigned female sex at birth). As of June 2024, 175 500 participants had exome sequencing available for analysis, and 5934 participants (3.4%) had a pathogenic variant in 81 genes known to increase risk for disease. Between 2013 and July 2024, 5119 results were disclosed to 5052 eligible participants, with 2267 (44.2%) associated with risk for cardiovascular disease, 2031 (39.7%) with risk for cancer, and 821 (16.0%) with risk for other conditions. Most results (3040 [59.4%]) were in genes outside of those with a CDC Tier 1 designation. Nearly 90% of participants (4425 [87.6%]) were unaware of their genomic risk prior to disclosure. In a survey of large-scale biobanks with genomic and electronic health record (EHR) data, only 25.0% (6 of 24) disclosed potentially actionable genomic results.

Conclusions and Relevance

In this large, genomics-informed cohort study from a single health system, 1 in 30 participants had a potentially actionable genomic finding. However, nearly 90% were unaware of their risk prior to screening, demonstrating the utility of genomic screening in identifying at-risk individuals. Most large-scale biobanks with genomic and EHR data did not return genomic results with potential medical relevance, missing opportunities to significantly improve genomic risk ascertainment for these individuals and to perform longitudinal studies of clinical and implementation outcomes in diverse settings.

Prevalence of Pathogenic Transthyretin Gene Variants in the Rocky Mountain Region

INTRODUCTION/AIMS

Hereditary transthyretin amyloidosis (ATTRv) is a genetic condition caused by pathogenic variants in the transthyretin (TTR) gene resulting in multisystem amyloid deposition, especially in peripheral nerve and heart. Information on the prevalence of ATTRv in the United States is limited. The objective of this study was to understand the prevalence and genetic ancestry in the Val142Ile population in a large regional US population.

METHODS

Colorado Center for Personalized Medicine (CCPM) biobank collects specimens from consenting adults seen throughout the University of Colorado Health System, a large tertiary healthcare system within the Rocky Mountain Region (RMR). Single nucleotide polymorphism (SNP) array genotyping and whole exome sequencing (WES) were performed for genetic research. Prevalence of TTR variants was studied.

RESULTS

A total of 73,346 participants had genetic testing; 151 (0.21%) individuals had a pathogenic or likely pathogenic TTR variant. The most common variant was Val142Ile, making up 82.61% of TTR variants found. Over four percent of people with African non-Hispanic ancestry had a Val142Ile variant.

DISCUSSION

The most common TTR variant in our study was Val142Ile, the most common variant in the United States (US). Similar to other US-based studies, affected individuals were predominantly of African, non-Hispanic ancestry. The availability of treatments for symptomatic ATTRv patients raises opportunities and challenges for biobanks as the identification of at-risk individuals places pressure on highly specialized centers and providers to see patients for screening and follow-up.

Hereditary Transthyretin Amyloidosis in Patients Referred to a Genetic Testing Program

BACKGROUND

Diagnosis of hereditary amyloid transthyretin (hATTR) amyloidosis with cardiomyopathy is frequently delayed, in large part because of symptom overlap with other cardiovascular diseases and limited provider knowledge of this disease. The sponsored and provider referred hATTR Compass Genetic Testing Program (Ionis, Carlsbad, CA; Ambry Genetics, Aliso Viejo, CA) provided no-cost genetic testing to adults with a family history or clinical suspicion of hATTR amyloidosis. This study aims to characterize patients with hATTR amyloidosis and increase awareness of genetic testing for hATTR.

METHODS AND RESULTS

Patients were referred to the hATTR genetic testing program, and a cross-sectional post hoc analysis was performed. A pathogenic TTR variant was identified in 1503 (6.6%) of 22 886 patients referred for genetic testing between June 2018 and March 2022. Patients were identified in all US states, 3 US territories, and Canada. Median age at testing was 63 years, and 44% were female. The p.V142I TTR variant was the most common (n=1263, 84.0%). Only 32% of patients with a pathogenic TTR variant reported a known family history; a lower percentage of Black individuals reported a known family history compared with other racial and ethnic groups. Black patients accounted for 23.7% of all patients referred and 81.9% of patients with the p.V142I variant.

CONCLUSIONS

This sponsored genetic testing program identified a large number of patients with a pathogenic TTR variant, notably, in geographic regions not previously reported, and demographic groups that are historically underrepresented in the literature.

Real-world utilization of guideline-directed genetic testing in inherited cardiovascular diseases

Background

Cardiovascular disease continues to be the leading cause of death globally. Clinical practice guidelines aimed at improving disease management and positively impacting major cardiac adverse events recommend genetic testing for inherited cardiovascular conditions such as dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), hereditary amyloidosis, and familial hypercholesterolemia (FH); however, little is known about how consistently practitioners order genetic testing for these conditions in routine clinical practice. This study aimed to assess the adoption of guideline-directed genetic testing for patients diagnosed with DCM, HCM, LQTS, hereditary amyloidosis, or FH.

Methods

This retrospective cohort study captured real-world evidence of genetic testing from ICD-9-CM and ICD-10-CM codes, procedure codes, and structured text fields of de-identified patient records in the Veradigm Health Insights Ambulatory EHR Research Database linked with insurance claims data. Data analysis was conducted using an automated electronic health record analysis engine. Patient records in the Veradigm database were sourced from more than 250,000 clinicians serving over 170 million patients in outpatient primary care and specialty practice settings in the United States and linked insurance claims data from public and private insurance providers. The primary outcome measure was evidence of genetic testing within six months of condition diagnosis.

Results

Between January 1, 2017, and December 31, 2021, 224,641 patients were newly diagnosed with DCM, HCM, LQTS, hereditary amyloidosis, or FH and included in this study. Substantial genetic testing care gaps were identified. Only a small percentage of patients newly diagnosed with DCM (827/101,919; 0.8%), HCM (253/15,507; 1.6%), LQTS (650/56,539; 1.2%), hereditary amyloidosis (62/1,026; 6.0%), or FH (718/49,650; 1.5%) received genetic testing.

Conclusions

Genetic testing is underutilized across multiple inherited cardiovascular conditions. This real-world data analysis provides insights into the delivery of genomic healthcare in the United States and suggests genetic testing guidelines are rarely followed in practice.

Musculoskeletal manifestations associated with transthyretin-mediated (ATTR) amyloidosis: a systematic review

BACKGROUND

Hereditary and wild-type transthyretin-mediated (ATTRv and ATTRwt) amyloidoses result from the misfolding of transthyretin and aggregation of amyloid plaques in multiple organ systems. Diagnosis of ATTR amyloidosis is often delayed due to its heterogenous and non-specific presentation. This review investigates the association of musculoskeletal (MSK) manifestations with ATTR amyloidosis and the delay from the onset of these manifestations to the diagnosis of ATTR amyloidosis.

METHODS

This systematic review utilized Medline and EMBASE databases. Search criteria were outlined using a pre-specified patient, intervention, comparator, outcome, time, study (PICOTS) criteria and included: amyloidosis, ATTR, and MSK manifestations. Publication quality was assessed utilizing Joanna Briggs Institute (JBI) critical appraisal checklists. The search initially identified 7,139 publications, 164 of which were included. PICOTS criteria led to the inclusion of epidemiology, clinical burden and practice, pathophysiology, and temporality of MSK manifestations associated with ATTR amyloidosis. 163 publications reported on ATTR amyloidosis and MSK manifestations, and 13 publications reported on the delay in ATTR amyloidosis diagnosis following the onset of MSK manifestations.

RESULTS

The MSK manifestation most frequently associated with ATTR amyloidosis was carpal tunnel syndrome (CTS); spinal stenosis (SS) and osteoarthritis (OA), among others, were also identified. The exact prevalence of different MSK manifestations in patients with ATTR amyloidosis remains unclear, as a broad range of prevalence estimates were reported. Moreover, the reported prevalence of MSK manifestations showed no clear trend or distinction in association between ATTRv and ATTRwt amyloidosis. MSK manifestations precede the diagnosis of ATTR amyloidosis by years, and there was substantial variation in the reported delay to ATTR amyloidosis diagnosis. Reports do suggest a longer diagnostic delay in patients with ATTRv amyloidosis, with 2 to 12 years delay in ATTRv versus 1.3 to 1.9 years delay in ATTRwt amyloidosis.

CONCLUSION

These findings suggest that orthopedic surgeons may play a role in the early diagnosis of and treatment referrals for ATTR amyloidosis. Detection of MSK manifestations may enable earlier diagnosis and administration of effective treatments before disease progression occurs.

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.

From the patient to the population: Use of genomics for population screening

Genomic medicine is expanding from a focus on diagnosis at the patient level to prevention at the population level given the ongoing under-ascertainment of high-risk and actionable genetic conditions using current strategies, particularly hereditary breast and ovarian cancer (HBOC), Lynch Syndrome (LS) and familial hypercholesterolemia (FH). The availability of large-scale next-generation sequencing strategies and preventive options for these conditions makes it increasingly feasible to screen pre-symptomatic individuals through public health-based approaches, rather than restricting testing to high-risk groups. This raises anew, and with urgency, questions about the limits of screening as well as the moral authority and capacity to screen for genetic conditions at a population level. We aimed to answer some of these critical questions by using the WHO Wilson and Jungner criteria to guide a synthesis of current evidence on population genomic screening for HBOC, LS, and FH.

Genomic Screening for Pathogenic Transthyretin Variants Finds Evidence of Underdiagnosed Amyloid Cardiomyopathy From Health Records

BACKGROUND

New treatments for transthyretin amyloidosis improve survival, but diagnosis remains challenging. Pathogenic or likely pathogenic (P/LP) variants in the transthyretin (TTR) gene are one cause of transthyretin amyloidosis, and genomic screening has been proposed to identify at-risk individuals. However, data on disease features and penetrance are lacking to inform the utility of such population-based genomic screening for TTR.

OBJECTIVES

This study characterized the prevalence of P/LP variants in TTR identified through exome sequencing and the burden of associated disease from electronic health records for individuals with these variants from a large (N = 134,753), primarily European-ancestry cohort.

METHODS

We compared frequencies of common disease features and cardiac imaging findings between individuals with and without P/LP TTR variants.

RESULTS

We identified 157 of 134,753 (0.12%) individuals with P/LP TTR variants (43% male, median age 52 [Q1-Q3: 37-61] years). Seven P/LP variants accounted for all observations, the majority being V122I (p.V142I; 113, 0.08%). Approximately 60% (n = 91) of individuals with P/LP TTR variants (all V122I) had African ancestry. Diagnoses of amyloidosis were limited (2 of 157 patients), although related heart disease diagnoses, including cardiomyopathy and heart failure, were significantly increased in individuals with P/LP TTR variants who were aged >60 years. Fourteen percent (7 of 49) of individuals aged ≥60 or older with a P/LP TTR variant had heart disease and ventricular septal thickness >1.2 cm, only one of whom was diagnosed with amyloidosis.

CONCLUSIONS

Individuals with P/LP TTR variants identified by genomic screening have increased odds of heart disease after age 60 years, although amyloidosis is likely underdiagnosed without knowledge of the genetic variant.