A rare variant of transthyretin-related amyloidosis associated with exclusive cardiomyopathy in a Hong Kong Chinese patient

Hereditary transthyretin cardiac amyloidosis proven by endomyocardial biopsy: a single-centre retrospective study and literature review

BACKGROUND

This study aimed to report the genotypes and phenotypes of hereditary transthyretin cardiac amyloidosis (hATTR-CA) in a Western Chinese cohort and review the genetic profiles of this disorder in the Chinese population.

METHODS

Transthyretin (TTR) gene sequencing of probands diagnosed with TTR cardiac amyloidosis and their relatives was performed at West China Hospital of Sichuan University from January 2018 to December 2021. All patients underwent endomyocardial biopsy for light and electron microscopy examinations. Clinical and essential examination materials were retrospectively collected and analysed.

RESULTS

TTR gene alteration was demonstrated in five probands and their two relatives. Three TTR variants were identified, namely, Ser23Asn, Glu54Leu and Thr60Ala. This study is the first to report Glu54Leu as pathogenic mutations in Chinese hATTR-CA patients. The Ser23Asn mutation was the most common mutation in this cohort. Five probands, including two males and three females, were all ethnic Han-Chinese. The median age at diagnosis and delay in diagnosis (interval from onset to diagnosis) was 56 years (range, 54-69 years) and 8 years (range, from 1 to 30 years), respectively. Three cases showed a defined family history of amyloidosis. Endomyocardial biopsies and TTR immunohistochemistry showed positive results in all patients. Two probands died 17.0 months and 21.0 months after diagnosis.

CONCLUSIONS

We identified one novel TTR variants causing hATTR-CA in the West Han Chinese population. To avoid misdiagnosis or delayed diagnosis of hATTR-CA, TTR genotypic screening and endomyocardial biopsy should be performed as soon as possible in cases with heightened clinical suspicion.

Clinical recommendations to diagnose and monitor patients with transthyretin amyloid cardiomyopathy in Asia

Transthyretin amyloid cardiomyopathy (ATTR‐CM) is a debilitating and life‐threatening condition with a heterogeneous clinical presentation. Recent guidelines from the United States and Europe have been published to guide clinical practice and to facilitate management conformity by covering current diagnostic and treatment strategies for patients with ATTR‐CM. These guidelines highlight the importance of an early diagnosis to optimize therapeutic outcomes, specifying the use of tests and imaging techniques to allow accurate, noninvasive diagnosis of ATTR‐CM. However, as regional practice variations across Asia may limit access to healthcare, availability of specific tests, and expertise in assessing diagnostic images, there is an ongoing need to provide an Asian perspective on these clinical guidelines. This review article provides practical recommendations for the diagnosis and monitoring of patients with ATTR‐CM in Asia, highlighting the need for additional guidelines to support a broad and diverse population, consider differing healthcare systems and diagnostic testing availability, and provide a flexible yet robust algorithm.