**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Author: Plínio José Whitaker Wolf
Institution: Instituto Dante Pazzanese de Cardiologia
City: São Paulo
State: São Paulo (SP)

**Main Body of the Abstract**
Introduction: Although hereditary transthyretin amyloidosis (ATTRv) is more frequent in the elderly population, it is not limited to older age groups. There are genetic variants that can lead to a more severe and earlier amyloidosis clinical presentation. We describe a series of cases with onset of symptoms under the age of 25 associated with the identification of a rare variant in the TTR gene.
Results: Three male patients from the same family with ATTRv confirmed by a positive molecular test for the p.F64S pathogenic variant, with a mean age at clinical presentation of 19±3 years. The baseline characteristics of the patients are shown in Table 1. All the patients had a mixed phenotype, with severe polyneuropathy, dysautonomia and cardiomyopathy. All had left ventricular hypertrophy, with a mean septal thickness/posterior wall of 15.6±4/13±3 mm. One patient had recurrent large pericardial effusion. No deaths occurred during follow-up (five years). All the patients received specific treatment for amyloidosis.
Discussion/Conclusion: We describe three relatives with a mixed and very early phenotype of ATTRv, determined by the p.F64S variant. This mutation is very rare and we found 7 cases described in the literature, all very young, with a predominantly polyneuropathic phenotype, but most with associated heart disease. The p.V50M variant can also occur in young people, but this occurs around the third decade of life. In conclusion, amyloidosis should not be seen as a disease exclusive to the elderly population and should therefore be considered as a differential diagnosis for ventricular hypertrophy in young people.



**Author Listing - Lead/ Submitting Author (we will be communicating with this individual): Name, Institution, City and State where the work was done. Co-authors will be added in a separate section.**
Author: Plínio José Whitaker Wolf
Institution: Instituto Dante Pazzanese de Cardiologia
City: São Paulo
State: São Paulo (SP)

**Main Body of the Abstract**
**Introduction**: Although hereditary transthyretin amyloidosis (ATTRv) is more frequent in the elderly population, it is not limited to older age groups. There are genetic variants that can lead to a more severe and earlier amyloidosis clinical presentation. We describe a series of cases with onset of symptoms under the age of 25 associated with the identification of a rare variant in the TTR gene.
**Results**: Three male patients from the same family with ATTRv confirmed by a positive molecular test for the p.F64S pathogenic variant, with a mean age at clinical presentation of 19±3 years. The baseline characteristics of the patients are shown in Table 1. All the patients had a mixed phenotype, with severe polyneuropathy, dysautonomia and cardiomyopathy. All had left ventricular hypertrophy, with a mean septal thickness/posterior wall of 15.6±4/13±3 mm. One patient had recurrent large pericardial effusion. No deaths occurred during follow-up (five years). All the patients received specific treatment for amyloidosis.
**Discussion/Conclusion**: We describe three relatives with a mixed and very early phenotype of ATTRv, determined by the p.F64S variant. This mutation is very rare and we found 7 cases described in the literature, all very young, with a predominantly polyneuropathic phenotype, but most with associated heart disease. The p.V50M variant can also occur in young people, but this occurs around the third decade of life. In conclusion, amyloidosis should not be seen as a disease exclusive to the elderly population and should therefore be considered as a differential diagnosis for ventricular hypertrophy in young people.



Transthyretin amyloidosis in the second decade of life: a rare genetic variant PB18 (#524)

We invite you to attend the XIX International Symposium on Amyloidosis to be held in Rochester, MN.

This symposium is organized as a hybrid meeting (with the focus on in-person) held from Sunday, May 26 through Thursday, May 30, 2024.

Together with the ISA Board and members of Mayo Clinic, a very attractive scientific hybrid program is being planned. The program will cover a variety of types of systemic amyloidosis: ATTR (hereditary and wild-type), AL (light-chain), AA and less frequent forms. There will be key lectures, specific symposia including those company sponsored, oral presentations and poster sessions of accepted abstracts.

COURSE DESCRIPTION
This program will provide a comprehensive review of state-of-the-art education in systemic amyloidosis: basic science, pathophysiology, diagnosis, current and emerging treatments. Scientific presentations will include competitive oral and poster abstracts. The rapid evolution of scientific discovery and expanding treatment options has created tremendous interest in the field and this meeting will fill and important gap in educating scientists and clinicians.