First description of Portuguese patients with cardiac amyloidosis and p.Val142Ile: more evidence of an “African variant” in Caucasians

Abstract

Objectives. Hereditary transthyretin amyloidosis caused by the (ATTRv) p. Val142Ile variant is a common cause of cardiac amyloidosis among Western African countries and Afro-Americans populations. However, in recent years, Caucasian patients have been identified in greater numbers, raising the question of whether this variant has been undeappreciated in this population. We now have new cases of cardiac amyloidosis caused by the p.Val142Ile from a center in northern Portugal. In addition, we reviewed and discussed the published data concerning p.Val142Ile in Caucasians. Design. Patients diagnosed with cardiac amyloidosis underwent genetic testing using TTR gene sequencing and their relatives were recommended for genetic counsellingand testing if a pathogenic TTR variant was found. In our center, we reviewed the clinical data of patients who had the p.Val142Ile variant. A review of published cases of p.Val142Ile in Caucasians was also performed, to which our data was compared. Results. We found three ATTRv patients with the p.Val142Ile variant (one homozygotic), all Caucasian males with a median age at diagnosis of 69 years old. All of them had heart failure and arrhythmias. During the follow-up period, two patients died. There were 47 unrelated unrelated Caucasian cases of ATTRv p.Val142Ile variant reported worldwide until May 2022. Conclusions. Our findings add to the mounting evidence that the global prevalence of p.Val142Ile is likely understated. This highlights the importance of the systematic screening of the TTR gene in amyloidosis and phenocopies, as well as larger epidemiologic studies to determine the true ATTRv p.Val142Ile prevalence in non-African communities.

Keywords:

• Heart failure
• cardiac amyloidosis
• TTR gene
• variant
• genetic testing
• family screening

Introduction

Amyloidosis is caused by the accumulation of misfolded proteins in various organs, including the heart, which results in progressive dysfunction [1]. The most common cause of amyloidosis is hereditary transthyretin amyloidosis (ATTR amyloidosis), a heterogeneous disorder with over 130 variants described in the transthyretin gene (TTR).

The variant c.424G > A (p.Val142Ile) is the most common cause of cardiomyopathy, usually affecting people over the age of 60 [2]. Although it is a slow-growing, late-onset cardiomyopathy, several studies have linked it to greater morbidity and mortality than wild-type or non-p.Val142Ile amyloidosis [3,4]. Extracardiac diagnosis is occasionally associated with carpal tunnel syndrome and, less frequently, neuropathy [5]. Because ATTRv p.Val142Ile is inherited in an autosomal dominant pattern, diagnosis is essencial for family screening. Carriers at risk should be offered appropriate surveillance, early disease detection and management, and family counselling, including reproductive options such as preimplantation genetic testing [6].

p.Val142Ile was thought to be almost exclusively found in West African countries and USA afro descendent patients [7], and this is supported by Genome Aggregation Database (gnomAD) which shows a 1.6% prevalence in the broader African population; this is, more than 25-fold higher than that observed in any other gnomAD super-population [8]. However, several cases have been scattered published in Caucasian patients, primarily in individuals of European descent from the Southern European subgroup, whose minor allele frequency is around 0.026% [8]. Mazzarotto et al. recently demonstrated the presence of a founder effect in central Italy, which should be considered as an alternative source of ATTRv in non-African communities [9].

Given the scarcity of data on Portuguese patients with cardiac amyloidosis caused by p.Val142Ile variant, we plan to describe those who hve been followed in our center in northern of Portugal with this variant. We also review and discuss published data on the p.Val142Ile in Caucasians.

Methods

In recent years, all patients with ATTR cardiac amyloidosis who were followed at our institution underwent genetic testing via TTR gene sequencing (Appendix) after given informed consent. If a pathogenic TTR variant was found, relatives were recommended for genetic counselling and testing; if carriers, electrocardiogram, echocardiogram, and bone cardiac scintigraphy (CS) screening was performed in accordance with the most recent recommendations [6].

Clinical information from patients with the p.Val142Ile variant was obtained retrospectively from electronic medical records. We also conducted a review of previously published p.Val142Ile Caucasians cases, which we compared to our patients.

Results

Between 2019 and 2021, our center performed ten genetic studies for ATTRv cardiac amyloidosis diagnosis, all on Caucasian patients. The p.Val142Ile variant was found in three unrelated patients with no reported consanguinity; were all male, with a mean age of 69 when diagnosed. They were from northern Portugal (Estarreja, Matosinhos e Torre de Moncorvo). Imaging data, including bone cardiac scintigraphy (CS), was consistent with the diagnosis ATTR amyloidosis (all patients presented a Perugini Score of two or three). At the time of diagnosis, all patients had heart failure (HF) symptoms and significant left ventricle (LV) hypertrophy, with a normal ejection fraction at diagnosis. An costumized clinical resume is provided below and in table one. There was no variant found in the remaining seven patients whose clinical data was consistent with ATTR cardiac amyloidosis.”

Case one

Case one was diagnosed with HF with preserved ejection fraction (pEF) in December 2018. An electrocardiogram revealed atrioventricular of the first degree (remaining work up in Table 1). Diuretic treatment improved clinical status. In September 2019, the patient developed complete atrioventricular block and a permanent pacemaker was implanted. Later, atrial fibrillation was discovered. The patient developed sensoric polyneuropathy, with no functional limitation, as well as and hepatic and kidney (Grade 3a) dysfunction. Tafamidis treatment began in In January 2020. The patient developed NYHA III HF, LV systolic dysfunction (LVEF 32%), and was hospitalized three times for congestion and worsening renal function. Since then, the patient has remained clinically stable (NYHA II with no further hospitalizations).

Table 1. Proband’s individual characteristics at diagnosis.

	Patient 1	Patient 2	Patient 3
Diagnoses’ age	73	69	66
Val142Ile-zigosity	Val142Ile Heterozygous	Val142Ile Heterozygous	Val142Ile Homozygous
Other organ dysfunction	CKD, III; Liver dysfunction	–	CKD, IV; Liver dysfunction
Cardiovascular risk factors	Arterial hypertension Diabetes mellitus	Smoking habits
Carpal tunnel syndrome	Yes (bilateral surgery 20 years earlier to diagnosis)	Yes (bilateral surgery 5 years earlier to diagnosis)	–
Cardiac presentation	CHF	CHF	CHF
Septum Hypertrophy (mm)	22	20	18
Initial LVEF (%)	55	60	65
Last LVEF (%)	32	48	39
Pulmonary artery pressure (mmHg)	50	32	54
Cardiac magnetic resonance LGE findings	Extensive intramyocardial LGE on LV and RV	–	–
Time to first hospitalization (year)	2	3	1
Rhythm disturbance	Advanced AVB; AF	Advanced AVB	–
Tafamidis	Approved	Waiting for approval	Refused

AF: atrial fibrillation; AVB: atrioventricular block; CHF: congestive heart failure; CKD: chronic kidney dysfunction; LGE - late gadolinium enhancement LV: left ventricle; LVEF: left ventricle ejection fraction; RV: righ ventricle.

Patient 1 had no siblings, and both his parents and grandparents had died with no known history of cardiomyopathy. He had three sons, two of whom were also p.Val142Ile carriers. Both carriers are in their 5th decade of life; one has arterial hypertension, mild LV hypertrophy (12 mm), and a Perugini scintigraphy scale of zero. The other carrier is healthy and has 2 daughters, a 21-year-old asymptomatic carrier daughter and a 10-year-old daughter who has not yet undergone genetic testing (See Figure 1(A)).

Figure 1. Genogram of patient 1 (A) and patient 3 (B).

Case two

In Jannuary 2019, case two was diagnosed with HF with pEF; an echocardiogram revealed severe left and right ventricle hypertrophy (17 mm of interventricular septum and 11 mm of the right ventricle free wall respectively), and electrocardiogram showed no conduction abnormalities. Complete atrioventricular block necessitated permanent pacemaker implantation in July 2020, and echocardiogram revealed right ventricular systolic dysfunction and mild LV systolic dysfunction. The patient died due to sudden cardiac death in April 2022.

The parents and grandparents of case two died with no known history of cardiomyopathy. He had 2 children (both in their thirties): the daughter tested negative for the ATTR p.Val142Ile, and the son refused to undergo the genetic testing.

Case three

Case three was diagnosed with HF during a first HF hospitalization in November 2017. He had severe LV hypertrophy, pulmonary hypertension and was in atrial fibrillation at the time of admission. He was homozygotic for p.Val142Ile. During a three-year follow-up, the patient developed advanced HF (left ventricular wall thinning, biventricular systolic dysfunction with a LVEF of 37%). Due to age, cachexia, and multiorgan dysfunction (including hepatic fibrosis), he was not considered a candidate for a heart transplant. The patient passed away in December 2020.

The patient’s father (97 years old) is still alive and well. His mother died at the age of 80, also asymptomatic (no genetic test was performed on both). His sister is a heterozygous 67 years old carrier with normal echocardiogram and bone cardiac scintigraphy. His two sons, in their thirties and carriers of p.Val142Ile, have normal echocardiograms. He has three granddaughters, all of whom are under the age of 18. The patient’s nieces (sister’s daughters) are in their forties and asymptomatic (See Figure 1(B)).

Review of the literature

Until May 2022, a total of 47 Caucasians with ATTRv p.Val142Ile were reported worldwide (Table 2 and Figure 2).

Figure 2. Summary map of previous reports of Caucasian patients with the Val142Ile ATTRv.

Table 2. Resume of Caucasian p.Val142Ile cases published.

Author	Gillmore et al. [10]	Hamidi et al. [11]	Ammirati et al. [12]	Swiecicki et al. [13]	Cappelli et al. [14]	Marrero Negrin et al. [16]	Gentile et al. [15]						Rasmussen et al. [17]	Trachtenberg et al. [18]
Publication Year	1991	2001	2012	2015	2016	2019	2020						2022	2022
Number of patients identified/study	1	1	1	5	5	1	6						1	25
Mean diagnoses’ age	83	76	64	UK	73	57	65						71	UK
Gender	Male	Male	Male	UK	UK	Male	UK						Male	UK
Val142Ile-zigosity	Het	Het	Het	UK	UK	Homo	Het	Het	Homo	Het	Het^b	Het	Het	UK
Presentation	CHF	CHF	CHF	UK	UK	CHF	CHF	CHF	NP	CHF	NP	CHF	CHF	UK
NYHA	II	II	II-III	UK	II- III	II	II	II	IV	II	II	II	II	UK
Other organ dysfunction	–	–	–	UK	UK	–	MO	–	–	–	–	Renal	–	UK
Carpal tunnel syndrome	–	Yes	–	UK	UK	Yes	Yes	Yes	Yes	Yes	–	Yes	Yes	UK
Mean septum hypertrophy, grade or mm	UK	16.2	Moderate	UK	18	19	17						15	UK
Mean LV function, grade or LVEF (%)	Normal	Normal	Normal	UK	36	54	UK						52	UK
Months to first hospitalization	UK	UK	14	UK	UK	5	UK						–	UK
Arrythmia/PM	AF	1st AVB	Hemi block	UK	UK	UK	PM	PM	–	–	–	PM	–	UK
Follow up	UK	UK	Cardiac Transplant	UK	UK	UK	D	–	–	–	D	D	–	UK
Tafamidis	NA	NA	NA	NA	UK	UK	Yes	–	–	–	–	Yes	–	UK
Number of family cases identified/study	0	1	2	UK	UK	1^a	5						1	UK
Number of family carriers identified/study	2	1	3	UK	UK	6 (1^a)	3						1	UK

^aV122I homozygous; ^bV122I homo/E89Q compound heterozygous. AF: atrial fibrillation; AVB: atrio ventricle block; CTS: carpal tunnel syndrome; D: Death; LV: left ventricle; Het: Heterozygous; Homo: homozygosity; MO: multiorgan dysfunction; NA: not applicable; NP: Neuropathy; PM: pacemaker; UK: unknow.

Gillmore et al. [10] described the first case in an elderly man admitted with an ischemic stroke in England in 1991; atrial fibrillation and cardiac amyloidosis with the p.Val142Ile were later identified [10]; two carriers were identified. Hamidi et al. [11] described the second case of an American Caucasian with English Ancestry, which resulted in the identification of another diseased relative and one carrier. Ammirati et al. [12] described a patient born in southern Italy who underwent heart transplantation; nine relatives were carriers of the variant and three experiencing cardiac symptoms. Swiecicki et al. [13] published a retrospective study of 266 patients with cardiac amyloidosis who were followed at Mayo Clinic, Minnesota, USA: 5 Caucasians were found to have the p.Val142Ile variant (no individual information was described). Cappelli et al. [14] described five Caucasian patients, four from Tuscany, and one from Argentina/Spain. All had late onset severe restrictive cardiomyopathy with no neurological involvement. Gentile et al. [15] described twelve Sicilian patients from 7 different families; among these, one homozygous for the Va142Ile and another compound heterozygous P.Val142Ile/E89Q, five symptomatic relatives and three asymptomatic carriers. It should be noted that three of the patients had neurologic symptoms (peripheral neuropathy and/or autonomic dysfunction). Marrero Negrin et al. [16] described a Spanish homozygous patient, which lead to the discovery of a related case and six carriers. Rasmussen et al. found one p.Val142Ile family with one proband among 102 patients in Danish amyloidosis center cohort. Probant’s family was investigated, and one brother eas found to have the ATTRv p.Val142Ile variant; their father died with no reported cardiac symptom; a post-mortem genetic test revealed this variant was present [17]. Trachtenberg et al. 25 Caucasian ancestry patients with the ATTRv p.Val142Ile (no detailed data) in a large genetic testing program in the United States that included 21 415 self-reported individuals [18].

Discussion

In this study, we re-exame the clinical data of Caucasian patients with cardiac amyloidosis and ATTRv p.Val142Ile, including three new Portuguese patients and 47 previously reported cases. As far as we know, there is no review article or large-scale epidemiological study on the subject. Heterogenic presentation will be highlighted because it frequently contributes to misdiagnosis [19].

The “African” variant, pVal142Ile, has been identified in at least 50 Caucasians across from across Europe. The highest prevalence has been reported in Sicily and a recent study showed a higher than expected prevalence in Tuscany as a result of the founder effect [9]. Thefore, this variant is not limited to Afro-descendants and should be tested in Caucasian patients with cardiac amyloidosis. Epidemiological studies are required to determine the true prevalence of p.Val142Ile in Caucasians.

The overall median age at diagnosis was 69 years old, and in the few cases where the patient gender was specified [5], all of the patients were male (as in our cases). HF was the main clinical presentation (9 published cases plus our 3 cases). Severe septum hypertrophy (mean of published cases vs Portuguese patients; 17 vs 19 mm), conduction disturbance (requiring permanent pacemaker in at least 5 patients), arrhythmia (atrial fibrillation in at least 2 patients), and carpal tunnel syndrome (10 patients described on total) were also relevant findings. Other characteristics such as months to first hospitalization, survival, and management were described only infrequently.

Homozygosity for the p.Val142Ile variant has been linked to a poorer prognosis when compared to heterozygosity [16]. The three patients described here had a younger age at diagnosis (62 years), significant interventicular septum hypertrophy (mean of 19 mm), and rapid progression to advanced HF with a significant increase in plasma B type natriuretic peptides levels. These characteristics that homozygotes should be closely monitored. Surprisingly, none of the three probands had a family history of cardiac disease at the time of presentation.

According to the data, ATTRv p.Val142Ile has variable expression, which is most likely due to other genetic modifiers or epigenetic factors. Though cardiomyopathy is undoubtedly the most common presentation and neuropathy is rare (as opposed to the second most common ATTRv p.Val30Met), one ATTRv p.Val142Ile patient presented with neurologic symptoms at onset, and another ate the age of 73 with only axonal neuropathy and no evidence of heart disease (normal cardiac MRI and ^99mTc-DPD scintigraphy) [15,19]. The patient with p.Val142Ile/E109Q initially presented with neuropathy before progressing to cardiomyopathy at a faster rate. This suggests other TTR variants may play an interacting role in disease expression. E109Q is a TTR gene pathogenic variant associated with a mixed phenotype (cardiac and neurologic features) [20].

This study has several limitations, the most significant of which is the small number of patients from a single centre. Because all published cases are retrospective descriptions, there is a lack of data about early symptoms/manifestation of the disease, and thus what we know about the clinical manifestations in p.Val142Ile carriers may be skewed. Nevertheless, we are resuming three new cases of ATTRv p.Val142Ile in Portugal for the first time. There was no thorough genealogical or genetic analysis to determine if they are remotely related or if the Iberian Peninsula/Portugal also has a founder effect. Similarly to Italy, as described by Olalde et al. and Bycroft et al. the Iberian population bears clear genetic traces of several population movements from north Africa (back to 860–1120 CE during Muslim conquest and subsequent Reconquista) and the Sub-Saharan region (from the mid-fifteenth century to the end of the eighteenth century during modern slave trade) [21,22]. It is currently unknown whether our cases are the result of a founder result or recent admixture events.

Finally, there is mounting evidence that the global prevalence of p.Val142Ile is likely understated. TTR genetic testing should be performed in all patients with ATTR cardiac amyloidosis or phenocopies to allow for proper management and family screening planning. Larger epidemiologic studies are needed to determine the true prevalence of ATTRv p.Val142Ile in non-African communities. Patients from southern Europe seem to have a higher prevalence, but more research is needed to confirm this assumption.

Ethical approval

The study was performed according recommendations of Helsinki Declaration.

Acknowledgements

The authors acknowledge to all patients and their families who contributed to this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

No funding.

Appendix

Genetic testing protocol

DNA was extracted from 250 ml of peripheral blood samples collected in EDTA-containing vials. Coding regions, including intron/exon boundaries of TTR gene (NM_000371) were amplified in four reactions. Primer sequences were designed by means of UCSC Genome Browser (http://genome.ucsc.edu/cgi-bin/hgPcr) and are available upon request. The PCR amplification of 4 exons and flanking intronic regions of the TTR gene was performed using 50–100 ng of genomic DNA. Cycling parameters for each reaction were optimized for all exons. Amplification was performed with Type-it DNA polymerase (1 U) was added for each 25 ml reaction. PCR was performed by a multiblock Veriti PCR System. PCR products were purified according to Ampure PCR Purification Kit protocol (Quiagen GmbH), sequenced using Big Dye Terminator chemistry (Applied Biosystems) and run on 3500 DNA Analysers (Applied Biosystems). Data obtained from the Seqscape Analysis Software v2.7 (Applied Biosystems) were aligned with the wild-type TTR gene sequence. The presence of the pathogenic variant was confirmed by a new independent PCR.