**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.**
Hans Christian Beck, Odense University Hospital, Odense, Denmark

**Main Body of the Abstract**
Background: Mass spectrometry-based proteomics (MS) has become the method of choice for the detection of amyloidogenic protein in a quantitative manner in organ biopsies and fat aspirates. MS does not only identify the subtype-specific protein but also measures an amyloid protein signature that is shared across all amyloidosis subtypes in various tissues. An amyloid positive biopsy from suspected involved organ is diagnostic but it is also an invasive procedure with some risk of complication. In contrast, fat aspirate is a minimal invasive procedure and has been shown to be a fairly sensitive screening for systemic amyloidosis. 
Objective:  We developed a method for sample preparation of amyloid plaques isolated from fat aspirates by laser microdissection (LMD) followed by the identification of the amyloidogenic proteins using ultra-sensitive MS-based proteomics.
Results: LMD-MS significantly improved the detection of amyloidogenic proteins over background proteins, especially in fat aspirates that showed weak staining with Congo Red. Moreover, total analysis time was kept below three hours. Using this protocol we retrospectively and successfully subtyped fat aspirates collected from patients suspected with systemic amyloidosis, including biopsies that showed weak CR staining, and where subtyping using existing MS-based methods have been unsuccesfully.
Summary & Conclusion: A novel ultra-senvitive LMD-MS-based method for amyloid subtyping of CR positive fat aspirates was developed. Using this method, we were able to subtype fat aspirates with low amounts of amyloid plaques, which it has not been possible to subtype using MS-based methods used so far, even without sacrificing total analysis time.



**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.**
Hans Christian Beck, Odense University Hospital, Odense, Denmark

**Main Body of the Abstract**
**Background:** Mass spectrometry-based proteomics (MS) has become the method of choice for the detection of amyloidogenic protein in a quantitative manner in organ biopsies and fat aspirates. MS does not only identify the subtype-specific protein but also measures an amyloid protein signature that is shared across all amyloidosis subtypes in various tissues. An amyloid positive biopsy from suspected involved organ is diagnostic but it is also an invasive procedure with some risk of complication. In contrast, fat aspirate is a minimal invasive procedure and has been shown to be a fairly sensitive screening for systemic amyloidosis. 
**Objective:**  We developed a method for sample preparation of amyloid plaques isolated from fat aspirates by laser microdissection (LMD) followed by the identification of the amyloidogenic proteins using ultra-sensitive MS-based proteomics.
**Results:** LMD-MS significantly improved the detection of amyloidogenic proteins over background proteins, especially in fat aspirates that showed weak staining with Congo Red. Moreover, total analysis time was kept below three hours. Using this protocol we retrospectively and successfully subtyped fat aspirates collected from patients suspected with systemic amyloidosis, including biopsies that showed weak CR staining, and where subtyping using existing MS-based methods have been unsuccesfully.
**Summary & Conclusion:** A novel ultra-senvitive LMD-MS-based method for amyloid subtyping of CR positive fat aspirates was developed. Using this method, we were able to subtype fat aspirates with low amounts of amyloid plaques, which it has not been possible to subtype using MS-based methods used so far, even without sacrificing total analysis time.



An ultra-sensitive laser microdissection-mass spectrometry-based method for the identification of subtype specific amyloidogenic proteins from fat aspirates PA79 (#458)

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.