**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.**
Aina Yamaguchi, Department of Molecular Pathology, University of Fukui, Fukui, Japan

**Main Body of the Abstract**
Background: Clinical presentation of systemic amyloidosis differs among subtypes, and accurate subtype classification is important for choosing the treatment. ATTR amyloidosis was the predominant among the recently consulted amyloidosis cases in Japan. Objective: To reveal the latest subtype frequency of systemic amyloidosis among autopsy cases in Japan. Methods: We analyzed systemic amyloidosis cases autopsied from January 2017 to December 2018, that were listed in the Annuals of the Pathological Autopsy Cases in Japan, Volumes 60, 61. The Annuals are edited by the Japanese Society of Pathology and list all cases autopsied during the year at the hospitals registered in the Japanese Society of Pathology. When the subtype was unclear, we performed a questionnaire survey, immunohistochemistry with in-house rabbit polyclonal anti-κ116-133, anti-λ118-134, and anti-transthyretin115-124 antibodies, and proteomic analysis (Figure). Results:Out of 481 systemic amyloidosis cases listed in the Annuals, 411 cases were available for analysis (85.4%). We classified 399 of these systemic amyloidosis cases. ATTR was the most common subtype (44.4%, n=177), followed by AL (38.8%, n=155). AA and Aβ2M were 9.3% (n=37) and 6.0% (n=24), respectively. Double deposition of amyloid was identified in 1.6% (n=6). In 168 cases (42.1%), systemic amyloidosis was the main cause of death. Of these cases, AL was the most common subtype (47.6%, n=80), followed by ATTR (41.1%, n=69). Conclusion: ATTR is the most predominant subtype among the current autopsy cases in Japan. Acknowledgements:We thank all the Japanese pathologists who participated in this study.



**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.**
Aina Yamaguchi, Department of Molecular Pathology, University of Fukui, Fukui, Japan

**Main Body of the Abstract**
**Background:** Clinical presentation of systemic amyloidosis differs among subtypes, and accurate subtype classification is important for choosing the treatment. ATTR amyloidosis was the predominant among the recently consulted amyloidosis cases in Japan. **Objective:** To reveal the latest subtype frequency of systemic amyloidosis among autopsy cases in Japan. **Methods:** We analyzed systemic amyloidosis cases autopsied from January 2017 to December 2018, that were listed in the Annuals of the Pathological Autopsy Cases in Japan, Volumes 60, 61. The Annuals are edited by the Japanese Society of Pathology and list all cases autopsied during the year at the hospitals registered in the Japanese Society of Pathology. When the subtype was unclear, we performed a questionnaire survey, immunohistochemistry with in-house rabbit polyclonal anti-κ~116-133~, anti-λ~118-134~, and anti-transthyretin~115-124~ antibodies, and proteomic analysis (Figure). **Results:**Out of 481 systemic amyloidosis cases listed in the Annuals, 411 cases were available for analysis (85.4%). We classified 399 of these systemic amyloidosis cases. ATTR was the most common subtype (44.4%, n=177), followed by AL (38.8%, n=155). AA and Aβ2M were 9.3% (n=37) and 6.0% (n=24), respectively. Double deposition of amyloid was identified in 1.6% (n=6). In 168 cases (42.1%), systemic amyloidosis was the main cause of death. Of these cases, AL was the most common subtype (47.6%, n=80), followed by ATTR (41.1%, n=69). **Conclusion:** ATTR is the most predominant subtype among the current autopsy cases in Japan. **Acknowledgements:**We thank all the Japanese pathologists who participated in this study.



Subtype frequency of systemic amyloidosis listed in the Annual of the Pathological Autopsy Cases in Japan PA97 (#342)

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.