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.

Association of the transthyretin variant V122I with polyneuropathy among individuals of African ancestry.

Hereditary transthyretin-mediated (hATTR) amyloidosis is an underdiagnosed, progressively debilitating disease caused by mutations in the transthyretin (TTR) gene. V122I, a common pathogenic TTR mutation, is found in 3-4% of individuals of African ancestry in the United States and has been associated with cardiomyopathy and heart failure. To better understand the phenotypic consequences of carrying V122I, we conducted a phenome-wide association study scanning 427 ICD diagnosis codes in UK Biobank participants of African ancestry (n = 6062). Significant associations were tested for replication in the Penn Medicine Biobank (n = 5737) and the Million Veteran Program (n = 82,382). V122I was significantly associated with polyneuropathy in the UK Biobank (odds ratio [OR] = 6.4, 95% confidence interval [CI] 2.6-15.6, p = 4.2 × 10-5), which was replicated in the Penn Medicine Biobank (OR = 1.6, 95% CI 1.2-2.4, p = 6.0 × 10-3) and Million Veteran Program (OR = 1.5, 95% CI 1.2-1.8, p = 1.8 × 10-4). Polyneuropathy prevalence among V122I carriers was 2.1%, 9.0%, and 4.8% in the UK Biobank, Penn Medicine Biobank, and Million Veteran Program, respectively. The cumulative incidence of common hATTR amyloidosis manifestations (carpal tunnel syndrome, polyneuropathy, cardiomyopathy, heart failure) was significantly enriched in V122I carriers compared with non-carriers (HR = 2.8, 95% CI 1.7-4.5, p = 2.6 × 10-5) in the UK Biobank, with 37.4% of V122I carriers having at least one of these manifestations by age 75. Our findings show that V122I carriers are at increased risk of polyneuropathy. These results also emphasize the underdiagnosis of disease in V122I carriers with a significant proportion of subjects showing phenotypic changes consistent with hATTR amyloidosis. Greater understanding of the manifestations associated with V122I is critical for earlier diagnosis and treatment.

Description of a large cohort of Caucasian patients with V122I ATTRv amyloidosis: Neurological and cardiological features.

V122I is one of more than 130 mutations in transthyretin gene associated with hereditary TTR (ATTRv) amyloidosis. Main clinical expression is an infiltrative pseudohypertrophic cardiomyopathy with mild or no neurological symptoms. It is particularly common among African-Americans (prevalence: 3%-4%). We report 12 subjects from seven unrelated Caucasian families hailing from Sicily and carrying the V122I mutation. One patient was homozygous for V122I and in another family two subjects also carried the E89Q variant in compound heterozygosity. All the subjects underwent neurologic/neurophysiologic evaluation and cardiologic baseline tests; in five of them, cardiac magnetic resonance and/or (99 m) Tc-DPD scintigraphy were performed. Three of 12 subjects were asymptomatic carriers. Of the remaining nine subjects, in four of nine patients, the nerve conduction studies revealed a polyneuropathy; in one of them, this represents the only sign of disease after 5 years of follow-up. In eight of nine subjects, we found a hypertrophic restrictive cardiomyopathy and cardiac failure, associated with a carpal tunnel syndrome. Although in non-Afro-American individuals V122I prevalence is low, subjects carrying this mutation have been identified in the United Kingdom, Italy, and France. Our report describes a large cohort of V122I Caucasian patients from a non-endemic area, confirming the possible underestimation of this mutation in the non-African population. Moreover, it highlights the heterogeneity in the genotype-phenotype correlation of ATTRv mutations, suggesting that the presence of a polyneuropathy has to be identified as soon as possible, since available treatments are, in Europe, so far authorized only for ATTRv amyloid peripheral neuropathy.

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

Importance: Hereditary transthyretin (TTR) amyloid cardiomyopathy (hATTR-CM) due to the TTR V122I variant is an autosomal-dominant disorder that causes heart failure in elderly individuals of African ancestry. The clinical associations of carrying the variant, its effect in other African ancestry populations including Hispanic/Latino individuals, and the rates of achieving a clinical diagnosis in carriers are unknown. Objective: To assess the association between the TTR V122I variant and heart failure and identify rates of hATTR-CM diagnosis among carriers with heart failure. Design, Setting, and Participants: Cross-sectional analysis of carriers and noncarriers of TTR V122I of African ancestry aged 50 years or older enrolled in the Penn Medicine Biobank between 2008 and 2017 using electronic health record data from 1996 to 2017. Case-control study in participants of African and Hispanic/Latino ancestry with and without heart failure in the Mount Sinai BioMe Biobank enrolled between 2007 and 2015 using electronic health record data from 2007 to 2018. Exposures: TTR V122I carrier status. Main Outcomes and Measures: The primary outcome was prevalent heart failure. The rate of diagnosis with hATTR-CM among TTR V122I carriers with heart failure was measured. Results: The cross-sectional cohort included 3724 individuals of African ancestry with a median age of 64 years (interquartile range, 57-71); 1755 (47%) were male, 2896 (78%) had a diagnosis of hypertension, and 753 (20%) had a history of myocardial infarction or coronary revascularization. There were 116 TTR V122I carriers (3.1%); 1121 participants (30%) had heart failure. The case-control study consisted of 2307 individuals of African ancestry and 3663 Hispanic/Latino individuals; the median age was 73 years (interquartile range, 68-80), 2271 (38%) were male, 4709 (79%) had a diagnosis of hypertension, and 1008 (17%) had a history of myocardial infarction or coronary revascularization. There were 1376 cases of heart failure. TTR V122I was associated with higher rates of heart failure (cross-sectional cohort: n = 51/116 TTR V122I carriers [44%], n = 1070/3608 noncarriers [30%], adjusted odds ratio, 1.7 [95% CI, 1.2-2.4], P = .006; case-control study: n = 36/1376 heart failure cases [2.6%], n = 82/4594 controls [1.8%], adjusted odds ratio, 1.8 [95% CI, 1.2-2.7], P = .008). Ten of 92 TTR V122I carriers with heart failure (11%) were diagnosed as having hATTR-CM; the median time from onset of symptoms to clinical diagnosis was 3 years. Conclusions and Relevance: Among individuals of African or Hispanic/Latino ancestry enrolled in 2 academic medical center-based biobanks, the TTR V122I genetic variant was significantly associated with heart failure.

Identification of Transthyretin Cardiac Amyloidosis Using Serum Retinol-Binding Protein 4 and a Clinical Prediction Model.

Importance: Transthyretin cardiac amyloidosis (ATTR) is an underrecognized cause of heart failure (HF) in older individuals, owing in part to difficulty in diagnosis. ATTR can result from substitution of valine for isoleucine at codon 122 of the transthyretin (TTR) gene (V122I), present in 3.43% of African American individuals. Objective: To examine whether serum retinol-binding protein 4 (RBP4), an endogenous TTR ligand, could be used as a diagnostic test for ATTR V122I amyloidosis. Design, Setting, and Participants: In this combined prospective and retrospective cohort study performed at a tertiary care referral center, 50 African American patients 60 years or older with nonamyloid HF and cardiac wall thickening prospectively genotyped from September 1, 2014, through December 31, 2015, and a comparator cohort of 25 patients with biopsy-proven ATTR V122I amyloidosis recruited from September 1, 2009, through November 31, 2014, comprised the development cohort. Twenty-seven African American patients and 9 patients with ATTR V122I amyloidosis comprised the validation cohort. Main Outcomes and Measures: Circulating RBP4, TTR, B-type natriuretic peptide (BNP), and troponin I (TnI) concentrations and electrocardiographic, echocardiographic, and clinical characteristics were assessed in all patients. Receiver operating characteristic (ROC) analysis was performed to identify optimal thresholds for ATTR V122I amyloidosis identification. A clinical prediction rule was developed using penalized logistic regression, evaluated using ROC analysis and validated in an independent cohort of cases and controls. Results: Age, sex, and BNP and TnI concentrations were similar between the 25 patients with ATTR V122I amyloidosis (mean [SD] age, 72.2 [7.4] years; 18 male [72%]) and the 50 controls (mean [SD] age, 69.2 [5.7] years; 31 male [62%]). Serum RBP4 concentration was lower in patients with ATTR V122I amyloidosis compared with nonamyloid controls (31.5 vs 49.4 µg/mL, P < .001), and the difference persisted after controlling for potential confounding variables. Left ventricular ejection fraction was lower in patients with ATTR V122I amyloidosis (mean [SD], 40% [14%] vs 57% [14%], P < .001), whereas interventricular septal diameter was higher (mean [SD], 16 [3] vs 14 [2] mm, P < .001). The ROC analysis identified RBP4 as a sensitive identifier of ATTR V122I amyloidosis (area under the curve [AUC] = 0.78; 95% CI, 0.67-0.88). A clinical prediction algorithm composed of RBP4, TTR, left ventricular ejection fraction, interventricular septal diameter, mean limb lead QRS voltage, and grade 3 diastolic dysfunction yielded excellent discriminatory capacity for ATTR V122I amyloidosis (AUC = 0.97; 95% CI, 0.93-1.00), whereas a 4-parameter model, including RBP4 concentration, retained excellent discrimination (AUC = 0.92; 95% CI, 0.86-0.99). The models maintained excellent discrimination in the validation cohort. Conclusions and Relevance: A prediction model using circulating RBP4 concentration and readily available clinical parameters accurately discriminated ATTR V122I amyloidosis from nonamyloid HF in a case-matched cohort. This clinical algorithm may be useful for identification of ATTR V122I amyloidosis in elderly African American patients with HF.

Afro-Caribbean Heart Failure in the United Kingdom: Cause, Outcomes, and ATTR V122I Cardiac Amyloidosis.

BACKGROUND: It has been reported that subjects of African descent present with heart failure at a younger age and because of different causes than whites. We present contemporary data from UK Afro-Caribbean patients in London. METHODS AND RESULTS: All patients with heart failure presenting to St George's Hospital Heart Failure clinic between 2005 and 2012 were included (n=1392). Patients were predominantly white (71%) and male (67%), and median age at presentation was 73 years (range, 18-100 years). In 211 Afro-Caribbean patients, the most common cause of heart failure was nonischemic dilated cardiomyopathy in 27.5% (whites, 19.9%; P<0.001). Lower rates of ischemic cardiomyopathy were observed (13% versus 41%; P<0.001). The fourth most common cause of heart failure in Afro-Caribbeans was cardiac amyloidosis (11.4%). The prevalence may have been even higher as not all patients were tested for amyloidosis. Patients with ATTR V122I had the worst prognosis compared with other causes of Afro-Caribbean heart failure and white patients. To better understand this condition, we analyzed data from the largest international cohort of ATTR V122I patients, followed up at the UK National Amyloidosis Center (n=72). Patients presented with cardiac failure (median age, 75 [range, 59-90] years). Median survival was 2.6 years from diagnosis. CONCLUSIONS: In London, the cause of heart failure varies depending on ethnicity and affects age of presentation and outcomes. In Afro-Caribbean patients, ATTR V122I is an underappreciated cause of heart failure, and cardiomyopathy is often misattributed to hypertension. As promising TTR therapies are in development, increased awareness and proactive detection are needed.

Transthyretin Cardiac Amyloidosis in Black Americans.

Transthyretin-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive and hypertrophic heart disease and often goes undiagnosed. In the United States, the hereditary form disproportionately afflicts black Americans, who when compared with whites with wild-type transthyretin amyloidosis, a phenotypically similar condition, present with more advanced disease despite having a noninvasive method for early identification (genetic testing). Although reasons for this are unclear, this begs to consider the inadequate access to care, societal factors, or a biological basis. In an effort to improve awareness and explore unique characteristics, we review the pathophysiology, epidemiology, and therapeutic strategies for transthyretin amyloidosis and highlight diagnostic pitfalls and clinical pearls for identifying patients with amyloid heart disease.

Impact of liver transplantation on transthyretin-related ocular amyloidosis in Japanese patients.

OBJECTIVE: To evaluate the long-term impact of liver transplantation on ocular manifestations of familial amyloid polyneuropathy (FAP) in Japanese patients. METHODS: Medical records were retrospectively reviewed in a long-term follow-up study. Of 52 patients with FAP amyloidogenic transthyretin Val30Met, 22 patients underwent liver transplantation. We assessed ocular manifestations, including amyloid deposition at the pupillary border, pupillary border with irregularity, vitreous opacities, and glaucoma, in patients who underwent liver transplantation. In addition, we compared the clinical characteristics of vitreous opacities-the most common ocular manifestation of FAP-in patients who underwent liver transplantation and those who did not to determine the effect of transplantation on the progression of ocular amyloidosis. RESULTS: Mean time after FAP onset was 10 years and after liver transplantation was 7 years in patients who underwent liver transplantation. All ocular manifestations increased with time after transplantation. Eight patients (36%) developed vitreous opacities and 4 patients (18%) developed glaucoma during follow-up. Mean time from FAP onset to vitreous opacities onset was significantly shorter in patients with early-onset disease who underwent liver transplantation than in those who did not. CONCLUSIONS: Patients with FAP who undergo liver transplantation continue to have a long-term risk of severe ocular manifestations, especially vitreous opacities and glaucoma, which can restrict their daily lives, even after liver transplantation.

Complement C1Q polymorphisms modulate onset in familial amyloidotic polyneuropathy TTR Val30Met.

BACKGROUND: Familial amyloidotic polyneuropathy (FAP) TTR Val30Met is a lethal autosomal dominant sensorimotor and autonomic neuropathy due to a substitution of methionine for valine at position 30 of the transthyretin (TTR) gene. Amyloid, composed of mutated TTR, is deposited in the peripheral nervous system, myocardium and kidneys. Considerable variability in the age of onset and penetrance of the disease occurs in different countries. Penetrance in Sweden, Cyprus and Portugal is 2%, 28% and 80% respectively. Environmental and genetic factors are believed to contribute to this variability. So far, no single modifier gene has been unequivocally associated with age of onset or penetrance. METHODS: Candidate modifier genes were chosen from among those coding for chaperone proteins co-localized with TTR deposits in peripheral nerves. Seventy one TTRVal30Met carriers, 51 affected and 20 asymptomatic, belonging to 22 unrelated Greek-Cypriot families, and 59 normal controls were recruited for this study. Sequencing of the coding regions of TTR, serum amyloid P (APCS) and complement C1Q (A, B and C) genes was performed and APOE genotypes were determined. We searched for correlations between various polymorphisms of chaperone proteins and age of disease onset. RESULTS: Four new and 4 previously described single nucleotide substitutions were identified. One polymorphic site in C1QA (rs172378) and one in C1QC (rs9434) as well as the epsilon2 allele correlated with age of onset (p<0.05). CONCLUSIONS: Our study has identified polymorphisms which may influence the FAP-TTR Val30Met phenotype. Identifying modifier genes and their protein products may contribute to therapeutic advances.

Transthyretin Ala97Ser in Chinese-Taiwanese patients with familial amyloid polyneuropathy: genetic studies and phenotype expression.

BACKGROUND: Transthyretin (TTR) variants of familial amyloid neuropathies (FAP) form a heterogenous group of autosomal dominantly inherited diseases. TTR gene analysis in several nationalities (Japanese, Portuguese, French, and British) has shown many distinguishing characteristics in the genotype-phenotype correlation. In Chinese, there are only a few reports of private TTR gene mutations belonging to single kindred. MATERIALS AND METHODS: We collected five patients with autosomal dominant inheritant sensorimotor polyneuropathy and tissue-proved amyloid deposition. The diagnosis of FAP was established on the mutation of the TTR gene detected by direct sequencing. Haplotype analysis was conducted in four of these patients. RESULTS AND CONCLUSIONS: These five FAP patients shared an identical missense mutation, Ala97Ser, in the TTR gene. This mutation presented with a constellation of late-onset polyneuropathy, preceding carpal tunnel syndrome, and outstanding autonomic dysfunction. Heart was the most frequently involved vital organ. Haplotype analysis hinted independent origins although the numbers were limited. Our study is the first case series gathering from the Chinese-Taiwanese population. We proposed a possible hot-spot mutation of the TTR gene, Ala97Ser, in this ethnic.