The Val142Ile transthyretin cardiac amyloidosis

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.

Case Report: A rare homozygous patient affected by TTR systemic amyloidosis with a prominent heart involvement

Hereditary transthyretin amyloidosis is a severe, adult-onset autosomal dominant inherited systemic disease predominantly affecting the peripheral and autonomic nervous system, heart, kidney, and the eyes. We present a case of a Caucasian 65-year-old man with cardiac amyloidosis and the homozygous mutation Val142Ile (classically, Val122Ile) in the transthyretin gene. We provide a genotype-phenotype correlation regarding the genetic status of both heterozygous and homozygous individuals and their clinical conditions at the time of genetic testing.

Investigation on the high recurrence of the ATTRv-causing transthyretin variant Val142Ile in central Italy

The p.Val142Ile variant in transthyretin (encoded by the TTR gene) is the most common genetic cause of transthyretin-related amyloidosis. This allele is particularly prevalent in communities ofAfrican descent compared with populations of different ancestries, where its frequency is two orders of magnitude lower. For this reason, p.Val142Ile has always been considered an "African" variant, with limited studies performed on individuals of European descent. However, recent reports of higher-than-expected prevalence in European-ancestry populations question the African specificity of this allele. Here we show that the high recurrence of p.Val142Ile in central Italy is due to a founder effect and not to recent admixture from African populations, highlighting how this may be the case in other communities. This suggests a probable underestimate of the global prevalence of p.Val142Ile, and further emphasizes the importance of routine inclusion of TTR in gene panels used for clinical genetic testing in hypertrophic cardiomyopathy (independently of the patient's geographical origin), that transthyretin-related amyloidosis can mimic.

Prevalence of transthyretin-related amyloidosis in Tuscany: Data from the regional population-based registry

The limited available data regarding the prevalence of transthyretin amyloidosis, both for wild-type (ATTRwt) and hereditary form (ATTRv), is inferred from highly selected patients and subsequent extrapolations that limit the comprehension of the clinical disease impact. The Tuscan healthcare system in 2006 developed a web-based rare disease registry, to monitor and profile patients affected by rare diseases. Clinicians belonging to regional validated healthcare data centres can register patients at the diagnosis, with a rigorous approach and distinguishing the types of amyloidosis, i.e., ATTRwt versus ATTRv. Thanks to this data collection method, available from July 2006 and extended with electronic therapy plans related to a diagnosis since May 2017, we analysed prevalence and incidence of ATTR and its subtypes. On November 30th 2022, ATTRwt prevalence in Tuscany is 90.3 per 1,000,000 persons and ATTRv prevalence is 9.5 per 1,000,000 persons, whereas the annual incidence ranges from 14.4 to 26.7 per 1,000,000 persons and from 0.8 to 2.7 per 1,000,000 persons, respectively. The male gender is predominant in both forms. All except one patient showed evidence of cardiomyopathy. This epidemiological data requires attention, not only to increase the effort for the clinical management and earlier diagnosis, but also to underline the need for the disease-specific treatments.

Transbronchial cryobiopsy proven amyloid diffuse cystic lung disease complicating a transthyretin mutated (ATTRm) amyloidosis: a case report

We present a case report of transbronchial cryobiopsy proven diffuse amyloid cystic lung disease complicating a homozygous Val122Ile (V122I) transthyretin mutated amyloidosis (ATTRm). To the best of our knowledge, this is the first case in the literature reporting such pulmonary lesions in ATTRm amyloidosis, and notably diagnosed through cryobiopsy. A 51-year-old man from Mali with a past medical history of bilateral carpal tunnel syndrome presented erectile dysfunction, asthenia and worsening dyspnoea over the past year. He presented signs of cardiac failure; histological and radiological investigations diagnosed cardiac amyloidosis. He was found homozygote for the V122I mutation in transthyretin. A diffuse cystic lung disease (DCLD) was noted on computed tomography (CT) scan. We performed a transbronchial pulmonary cryobiopsy that revealed histological transthyretin amyloid deposits. This case report illustrates the safety and usefulness of cryobiopsy in the setting of DCLD and extends ATTRm amyloidosis as a possible cause of DCLD.

Frequency of hereditary transthyretin amyloidosis among elderly patients with transthyretin cardiomyopathy

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is increasingly recognized as a cause of heart failure in the elderly. Although wild-type transthyretin amyloidosis is the most frequent form of ATTR-CM found in the elderly, hereditary transthyretin amyloidosis (ATTRv) can also occur. We sought to determine the prevalence of ATTRv among elderly ATTR-CM patients, identify predictors of ATTRv and evaluate the clinical consequences of positive genetic testing in this population.

METHODS AND RESULTS

Prevalence of ATTRv in elderly ATTR-CM patients (≥70 years) was assessed in a cohort of 300 consecutive ATTR-CM patients (median age 78 years at diagnosis, 82% ≥70 years, 16% female, 99% Caucasian). ATTRv was diagnosed in 35 (12%; 95% confidence interval [CI] 3.1-8.8) and 13 (5.3%; 95% CI 5.6-26.7) patients in the overall cohort and in those ≥70 years, respectively. Prevalence of ATTRv among elderly female patients with ATTR-CM was 13% (95% CI 2.1-23.5). Univariate analysis identified female sex (odds ratio [OR] 3.66; 95% CI 1.13-11.85; p = 0.03), black ancestry (OR 46.31; 95% CI 3.52-Inf; p = 0.005), eye symptoms (OR 6.64; 95% CI 1.20-36.73; p = 0.03) and polyneuropathy (OR 10.05; 95% CI 3.09-32.64; p < 0.001) as the only factors associated with ATTRv in this population. Diagnosis of ATTRv in elderly ATTR-CM patients allowed initiation of transthyretin-specific drug treatment in 5 individuals, genetic screening in 33 relatives from 13 families, and identification of 9 ATTRv asymptomatic carriers.

CONCLUSIONS

Hereditary transthyretin amyloidosis is present in a substantial number of ATTR-CM patients aged ≥70 years. Identification of ATTRv in elderly patients with ATTR-CM has clinical meaningful therapeutic and diagnostic implications. These results support routine genetic testing in patients with ATTR-CM regardless of age.

Racial Differences in Val122Ile-Associated Transthyretin Cardiac Amyloidosis

BACKGROUND

The valine-to-isoleucine substitution (Val122Ile) is the most common variant of transthyretin (TTR) amyloidosis in the United States, affecting primarily individuals of African descent. This variant has been identified recently in a cluster of white individuals in Italy.

METHODS AND RESULTS

Clinical phenotype and chamber performance of Black and white individuals with Val122Ile TTR cardiac amyloidosis (ATTR-CA) were compared. Compared to white patients (n = 17), Black individuals (n = 53) had lower systolic blood pressures (110 vs 131 mmHg, <0.001), reduced pulse pressures (41 vs 58 mmHg; P < 0.001), and impaired renal function (eGFR 46 vs 67 mL/min/1.73m²; P < 0.001) at presentation. Systolic properties and arterial elastance were similar. Black patients had end-diastolic pressure-volume relationships that were shifted upward and leftward relative to those of white patients, indicating reduced left ventricular chamber capacitance. Pressure-volume area at a left ventricular end-diastolic pressure of 30 mmHg was lower in Black than in white individuals (8055 mmHg/mL vs 11,538 mmHg/mL; P = 0.008).

CONCLUSION

Despite presenting at ages similar to those of white patients, Black individuals with Val122Ile-associated ATTR-CA had a greater degree of cardiac chamber dysfunction at the time of diagnosis due to impaired ventricular capacitance. Whether these differences are attributable to amyloidosis or other cardiovascular disease requires further study.

Sex-related differences in clinical presentation and all-cause mortality in patients with cardiac transthyretin amyloidosis and light chain amyloidosis

We aimed to ascertain whether sex-related differences are relevant to clinical presentation, cardiac phenotype and all-cause mortality in different types of cardiac amyloidosis, a field still poorly investigated. Medical files from consecutive patients diagnosed with cardiac amyloidosis between 2000 and 2020, at Careggi University Hospital, were retrospectively evaluated. Over this period, 259 patients (12% females) were diagnosed with wild type transthyretin amyloidosis (wtATTR), 52 (25% females) with hereditary transthyretin amyloidosis (hATTR) and 143 (47% females) with light chain amyloidosis (AL). Women with wtATTR, compared to men, were significantly older at the time of diagnosis and showed higher National Amyloidosis Centre score, thicker normalized interventricular septum, higher diastolic dysfunction and worse right ventricular function. Females with hATTR and AL had lower normalized cardiac mass compared to men, otherwise, bio-humoral parameters, NYHA class, and ECG characteristics were similar. Comparing females and male with wtATTR, hATTR and AL, no differences in Kaplan-Meier curves for all-cause mortality were observed with regard to sex, p-value >0.05. In conclusion, we did not observe major differences in clinical expression related to sex in different types of cardiac amyloidosis: specifically, all-cause mortality was not affected. Nevertheless, women with wtATTR had echocardiographic signs of more advanced disease and higher NAC score at diagnosis suggesting a possible later recognition of disease compared to men.

Prevalence and Outcomes of p.Val142Ile TTR Amyloidosis Cardiomyopathy: A Systematic Review

BACKGROUND

The p.Val142Ile variant, predominantly found among people of African descent, is the most common cause of variant transthyretin amyloidosis and carriers predominantly develop a cardiomyopathy (variant transthyretin amyloidosis cardiomyopathy) phenotype. Yet, there are conflicting data on the prevalence and outcomes of p.Val142Ile variant carriers.

METHODS

We performed a systematic review of the prevalence and outcomes of p.Val142Ile variant transthyretin amyloidosis cardiomyopathy among subjects of African descent. We found 62 relevant articles after searching the MEDLINE databases from 1980 to 2020 that reported data for ≈150 000 subjects.

RESULTS

The reported worldwide prevalence of the p.Val142Ile variant is 0.3% to 1.6% in the general population. Among people of African descent, the reported prevalence from all studies ranges from 1.1% to 9.8%, but for studies with >1000 subjects, it is 3% to 3.5%. The prevalence of the p.Val142Ile variant in a region is dependent on the reported percentage of subjects who are of African descent in that region. p.Val142Ile variant transthyretin amyloidosis cardiomyopathy typically presents in the seventh to eighth decade of life and the majority of cases reported were male, with 25% to 38% diagnosed with atrial fibrillation. It was associated with a longitudinally worse quality of life and a lower adjusted survival compared with other types of transthyretin amyloidosis cardiomyopathy.

CONCLUSIONS

The p.Val142Ile variant is the most common variant of the transthyretin gene with most carriers being of African descent. The true penetrance is unknown but the p.Val142Ile variant is associated with increased rates of incident heart failure and portends a lower overall survival. Increased awareness could lead to earlier diagnosis and improved heart failure outcomes among those of African descent, which is of increasing importance given the advent of novel therapeutics for this disease.

Poor right ventricular function is associated with impaired exercise capacity and ventilatory efficiency in transthyretin cardiac amyloid patients

CardioPulmonary Exercise Test (CPET) is the gold standard to evaluate functional capacity in patients at high risk of heart failure (HF). Few studies with a limited number of subjects and conflicting results, analyzed the role of CPET in patients with systemic amyloidosis. Aims of our study were the assessment of the response to exercise in patients with Transthyretin amyloid (ATTR) cardiomyopathy (CA), and the correlation of clinical, biohumoral and echocardiographic parameters with CPET parameters, such as VO₂ peak and VE/VCO₂ slope. From February 2018 to March 2019, 72 cardiac ATTR patients were prospectively enrolled and underwent a complete clinical, biohumoral, echocardiographic and CPET assessment. All patients completed the exercise stress test protocol, without any adverse event. At CPET, they achieved a mean VO₂ peak of 14 mL/Kg/min and a mean VE/VCO₂ slope of 31. The blood pressure response to exercise was inadequate in 26 (36%) patients (flat in 25 and hypotensive in 1), while 49/72 patients (69%) showed an inadequate heart rate recovery. In multivariate analysis, s' tricuspidalic was the only independent predictor of VO₂ peak, while in the two test models performed to avoid collinearity, both TAPSE and s' tricuspidalic were the strongest independent predictors of VE/VCO₂ slope. Our data demonstrate the role of right ventricular function as an independent predictor of exercise capacity and ventilatory efficiency in ATTR. In CPET evaluation, a significant proportion of patients presented an abnormal arterial pressure response and heart rate variation to exercise.

Drug Discovery and Development in Rare Diseases: Taking a Closer Look at the Tafamidis Story

Rare diseases are increasingly recognized as a global public health priority. Governments worldwide currently provide important incentives to stimulate the discovery and development of orphan drugs for the treatment of these conditions, but substantial scientific, clinical, and regulatory challenges remain. Tafamidis is a first-in-class, disease-modifying transthyretin (TTR) kinetic stabilizer that represents a major breakthrough in the treatment of transthyretin amyloidosis (ATTR amyloidosis). ATTR amyloidosis is a rare, progressive, and fatal systemic disorder caused by aggregation of misfolded TTR and extracellular deposition of amyloid fibrils in various tissues and organs, including the heart and nervous systems. In this review, we present the successful development of tafamidis spanning 3 decades, marked by meticulous laboratory research into disease mechanisms and natural history, and innovative clinical study design and implementation. These efforts established the safety and efficacy profile of tafamidis, leading to its regulatory approval, and enabled post-approval initiatives that further support patients with ATTR amyloidosis.

Efficacy of Tafamidis in Patients With Hereditary and Wild-Type Transthyretin Amyloid Cardiomyopathy: Further Analyses From ATTR-ACT

OBJECTIVES

Tafamidis is an effective treatment for transthyretin amyloid cardiomyopathy (ATTR-CM), this study aimed to determine whether there is a differential effect between variant transthyretin amyloidosis (ATTRv) and wild-type transthyretin (ATTRwt).

BACKGROUND

ATTR-CM is a progressive, fatal disorder resulting from mutations in the ATTRv or the deposition of denatured ATTRwt.

METHODS

In pre-specified analyses from ATTR-ACT (Tafamidis in Transthyretin Cardiomyopathy Clinical Trial), baseline characteristics, all-cause mortality, and change from baseline to month 30 in 6-min walk test distance and Kansas City Cardiomyopathy Questionnaire Overall Summary score were compared in patients with ATTRwt and ATTRv.

RESULTS

There were 335 patients with ATTRwt (201 tafamidis, 134 placebo) and 106 with ATTRv (63 tafamidis, 43 placebo) enrolled in ATTR-ACT. Patients with ATTRwt (vs. ATTRv) had less advanced disease at baseline and a lower rate of disease progression over the study. The reduction in all-cause mortality with tafamidis compared with placebo was not different between ATTRwt (hazard ratio: 0.706 [95% confidence interval (CI): 0.474 to 1.052]; p = 0.0875) and ATTRv (hazard ratio: 0.690 [95% CI: 0.408 to 1.167]; p = 0.1667). Tafamidis was associated with a similar reduction (vs. placebo) in the decline in 6-min walk test distance in ATTRwt (mean ± SE difference from placebo, 77.14 ± 10.78; p < 0.0001) and ATTRv (79.61 ± 29.83 m; p = 0.008); and Kansas City Cardiomyopathy Questionnaire Overall Summary score in ATTRwt (12.72 ± 2.10; p < 0.0001) and ATTRv (18.18 ± 7.75; p = 0.019).

CONCLUSIONS

Pre-specified analyses from ATTR-ACT confirm the poor prognosis of untreated ATTRv-related cardiomyopathy compared with ATTRwt, but show the reduction in mortality and functional decline with tafamidis treatment is similar in both disease subtypes. (Safety and Efficacy of Tafamidis in Patients With Transthyretin Cardiomyopathy [ATTR-ACT]; NCT01994889).

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.

Increased Risk of Multiple Outpatient Surgeries in African-American Carriers of Transthyretin Val122Ile Mutation Is Modulated by Non-Coding Variants

Background: African-Americans (AAs) have a 3.5% carrier prevalence of Transthyretin (TTR) Val122Ile mutation (rs76992529), which is the genetic cause of a hereditary form of amyloidosis. Methods: We investigated the medical history of Val122Ile carriers and assessed the role of a non-coding variation in 4361 unrelated AAs. Results: We observed that the Ile122 allele was associated with a 6.8-fold increase in the odds of having 10 or more outpatient surgeries (p = 7.81 × 10⁻⁵). Stratifying the analysis by sex, the Ile122 allele was associated with a 15.2-fold increase in the odds of having 10 or more outpatient surgeries in men (p = 6.49 × 10⁻⁷). A similar sex difference was observed with respect to the association of Val122Ile with musculoskeletal and connective-tissue disorders in an independent cohort of British subjects (n = 361,194, p = 2.47 × 10⁻¹³; n_male = 167,020, p_male = 4.02 × 10⁻²⁴). In Val122Ile African-American carriers, we observed that haplotypes in the upstream region regulating TTR hepatic expression are associated with having 10 or more outpatient surgeries (p = 2.56 × 10⁻⁹). Conclusions: TTR Val122Ile showed a large effect with respect to an extreme phenotype identified in medical history that may be related to osteoarthritis, an early sign of the disease. Additionally, the non-coding variation appears to accelerate the negative consequences associated with Val122Ile mutation via TTR expression regulation.

Estimating the prevalence of allelic variants in the transthyretin gene by analysing large-scale sequencing data

Transthyretin amyloidosis (ATTR amyloidosis) is a rare disease characterised by extracellular deposition of amyloid fibrils composed by transthyretin. ATTR amyloidosis can be sub-classified as wild-type ATTR (ATTR-wt) or as hereditary amyloidosis (ATTR-m); the prevalence of both types are likely underestimated. There are tools that can help us to study ATTR-m, as gnomAD database. Our primary aim was to estimate prevalence of variants, especially amyloidogenic variants, in the TTR gene using gnomAD database. We analysed TTR missense variants found in gnomAD. The variables studied were classified according to their clinical significance and according to the different populations. We found 71 missense variants in the TTR gene. Eleven variants were described as affects function variants (prevalence 1:230). The most frequently detected variant were c.424G>A (p.(Val142Ile)) (prevalence 1:332, MAF 0.00151) and c.148G>A (p.(Val50Met)) (prevalence 1:4924, MAF 0.000102), which represented 88% and 5%, respectively, of all affects function variants detected. Seventeen variants were classified as probably affects function, 29 as unknown variants, 4 as probably does not affect function and 10 as does not affect function variants. In terms of different populations, c.424G>A (p.(Val142Ile)) was especially prevalent in African population (MAF 0.01602; prevalence of 1:31) and c.148G>A (p.(Val50Met)) in European population (MAF 0.000179; prevalence of 1:2792). Prevalence of amyloidogenic variants in the general population was higher than prevalence heretofore described. This difference could be explained by incomplete penetrance of the disease, but other factors contributing to this fact, fundamentally the underdiagnosis of the disease.

Epigallocatechin-3-gallate tolerability and impact on survival in a cohort of patients with transthyretin-related cardiac amyloidosis. A single-center retrospective study

Transthyretin-related (ATTR) cardiac amyloidosis is currently lacking a disease-modifying therapy. Despite demonstration of effectiveness in halting amyloid deposition, no study focused on epigallocatechin-3-gallate (EGCG) impact on patient survival. We sought to explore prognostic impact of EGCG in a cohort of lone cardiac ATTR patients. From the Florence Tuscan Regional Amyloid Centre database, we retrospectively selected ATTR patients treated with EGCG (675mg daily dose) for a minimum of 9 months, between March 2013 and December 2016. As a control group, we selected ATTR patients who received guideline-directed medical therapy alone. End point of the study was time to all cause death or cardiac transplantation. Sixty-five patients (30 treatment groups vs. 35 control groups) had a median follow-up of 691 days. There were no differences in baseline characteristics between groups. Five deaths occurred in EGCG group versus eight in control group; one patient underwent effective cardiac transplantation in EGCG group. There was no difference in survival estimates between EGCG and control group (60 ± 15% vs. 61 ± 12%, p = 0.276). EGCG was well tolerated, without major safety concerns. In a real-world cohort of ATTR patients with lone cardiac involvement, EGCG was a safe therapeutic option, but was not associated with survival improvement.

Non-coding variants contribute to the clinical heterogeneity of TTR amyloidosis

Coding mutations in TTR gene cause a rare hereditary form of systemic amyloidosis, which has a complex genotype-phenotype correlation. We investigated the role of non-coding variants in regulating TTR gene expression and consequently amyloidosis symptoms. We evaluated the genotype-phenotype correlation considering the clinical information of 129 Italian patients with TTR amyloidosis. Then, we conducted a re-sequencing of TTR gene to investigate how non-coding variants affect TTR expression and, consequently, phenotypic presentation in carriers of amyloidogenic mutations. Polygenic scores for genetically determined TTR expression were constructed using data from our re-sequencing analysis and the GTEx (Genotype-Tissue Expression) project. We confirmed a strong phenotypic heterogeneity across coding mutations causing TTR amyloidosis. Considering the effects of non-coding variants on TTR expression, we identified three patient clusters with specific expression patterns associated with certain phenotypic presentations, including late onset, autonomic neurological involvement, and gastrointestinal symptoms. This study provides novel data regarding the role of non-coding variation and the gene expression profiles in patients affected by TTR amyloidosis, also putting forth an approach that could be used to investigate the mechanisms at the basis of the genotype-phenotype correlation of the disease.

Liver dysfunction as predictor of prognosis in patients with amyloidosis: utility of the Model for End-stage Liver disease (MELD) scoring system

Amyloidosis prognosis is often related to the onset of heart failure and a worsening that is concomitant with kidney-liver dysfunction; thus the Model for End-stage Liver disease (MELD) may be an ideal instrument to summarize renal-liver function. Our aim has been to test the MELD score as a prognostic tool in amyloidosis. We evaluated 128 patients, 46 with TTR-related amyloidosis and 82 with AL amyloidosis. All patients had a complete clinical and echocardiography evaluation; overall biohumoral assessment included troponin I, NT-proBNP, creatinine, total bilirubin and INR ratio. The study population was dichotomized at the 12 cut-off level of MELD scores; those with MELD score >12 had a lower survival compared to controls in the study cohort (40.7 vs 66.3 %; p = 0.006). Either as a continuous and dichotomized variable, MELD shows its independent prognostic value at multivariable analysis (HR = 1.199, 95 % CI 1.082-1.329; HR = 2.707, 95 % CI 1.075-6.817, respectively). MELD shows a lower prognostic sensitivity/specificity ratio than troponin I and NT-proBNP in the whole study population and AL subgroup, while in TTR patients MELD has a higher sensitivity/specificity ratio compared to troponin and NT-proBNP (ROC analysis-AUC: 0.853 vs 0.726 vs 0.659). MELD is able to predict prognosis in amyloidosis. A MELD score >12 selects a subgroup of patients with a higher risk of death. The predictive accuracy seems to be more evident in TTR patients in whom currently no effective scoring systems have been validated.

Transthyretin V122I (pV142I)* cardiac amyloidosis: an age-dependent autosomal dominant cardiomyopathy too common to be overlooked as a cause of significant heart disease in elderly African Americans

Since the identification of a valine-to-isoleucine substitution at position 122 (TTR V122I; pV142I) in the transthyretin (TTR)-derived fibrils extracted from the heart of a patient with late-onset cardiac amyloidosis, it has become clear that the amyloidogenic mutation and the disease occur almost exclusively in individuals of identifiable African descent. In the United States, the amyloidogenic allele frequency is 0.0173 and is carried by 3.5% of community-dwelling African Americans. Genotyping across Africa indicates that the origin of the allele is in the West African countries that were the major source of the slave trade to North America. At autopsy, the allele was found to be associated with cardiac TTR amyloid deposition in all the carriers after age 65 years; however, the clinical penetrance varies, resulting in substantial heart disease in some carriers and few symptoms in others. The allele has been found in 10% of African Americans older than age 65 with severe congestive heart failure. At this time there are potential forms of therapy in clinical trials. The combination of a highly accurate genetic test and the potential for specific therapy demands a greater awareness of this autosomal dominant, age-dependent cardiac disease in the cardiology community.Genet Med advance online publication 19 January 2017.

The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa

Background

Transthyretin (TTR) pV142I (rs76992529‐A) is one of the 113 variants in the human TTR gene associated with systemic amyloidosis. It results from a G to A transition at a CG dinucleotide in the codon for amino acid 122 of the mature protein (TTR V122I). The allele frequency is 0.0173 in African Americans.

Methods

PCR‐based assays to genotype 2767 DNA samples obtained from participants in genetic studies from various African populations supplemented with sequencing data from 529 samples within the 1000 Genomes Project.

Results

The rs76992529‐A variant allele was most prevalent (allele frequency 0.0253) in the contiguous West African countries of Sierra Leone, Guinea, Ivory Coast, Burkina Faso, Ghana, and Nigeria. In other African countries, the mean allele frequency was 0.011.

Conclusions

Our data are consistent with a small number of founder carriers of the amyloidogenic TTR V122I (p.Val142Ile) allele in southern West Africa, with no apparent advantage or disadvantage of an allele carrying newborn reaching adulthood. In U.S. African Americans, the allele represents a significant risk for congestive heart failure late in life. If clinical penetrance is similar in African countries with high allele frequencies, then cardiac amyloidosis could also represent a significant cause of heart disease in the elderly in those populations.