Rare variant (p.Ser43Asn) of familial transthyretin amyloidosis associated with isolated cardiac phenotype: A case series with literature review

Background: p.Ser43Asn is a very rare transthyretin (TTR) mutation leading to familial amyloidosis of transthyretin type, ATTR amyloidosis. It was previously observed in four patients worldwide and is associated almost invariably with an isolated cardiac phenotype. Methods and Results: We report here on an Italian family with early-onset cardiomyopathy and aggressive disease course in the affected individuals leading untreated to cardiac death before 55 years of age. We describe the clinical phenotype and imaging findings of two affected siblings, who were treated with tafamidis at an early disease stage, and their affected mother, who died 9 years ago due to refractory heart failure. The review of the available literature highlights the fact that until recently ATTR amyloidosis may have been misdiagnosed as other types of hypertrophic cardiomyopathy. Conclusion: A better characterization of the genotype-phenotype associations is crucial to achieve optimal outcomes and facilitate informed decisions when treating individuals with rare mutations.