**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.**
Jessica R Chapman, Memorial Sloan Kettering Cancer Center, New York, NY

**Main Body of the Abstract**
The prevalence of plasma cell neoplasms and its precursors increase with age . Similarly, wild type ATTR wild type is most diagnosed in older adults and higher rates of MGUS occur in ATTR patients as compared to the general population. The clinical symptoms of systemic immunoglobulin light chain amyloidosis and ATTR are similar and establishment of diagnosis by mass spectrometry is critical since either ATTR or AL amyloidosis is possible.
To highlight the necessity of mass spectrometry-based typing in the diagnosis of ATTR or AL amyloidosis in a cohort of patients with a known MGUS or SM diagnosis, a clinical syndrome consistent with amyloidosis and who falls in the demographic characteristic of ATTR.
Amyloid protein identification by liquid chromatography mass spectrometry (LC-MS) was performed. Congo red positive FFPE tissue was microdissected. Proteins were extracted from the tissue, reduced, alkylated, and digested with trypsin. Samples were analyzed on an UltiMate™3000 RSLCnano and Q-Exactive Plus mass spectrometer.
Five patients with a diagnosis of MGUS or SM had Congo red positive deposits identified in bone marrow or fat pad biopsies that were determined to have a peptide profile consistent with ATTR. Amyloid deposition was restricted to the periosteum in all four bone marrow biopsies and in the fat pad biopsy deposition was only in the extracellular regions of the tissue. Only one patient had a documented cardiomyopathy.
Amyloid typing by MS determined that a set of 5 patients had cooccurring ATTR and MGUS or SM despite initial assumptions of an AL amyloidosis diagnosis.



Amyloid typing by mass spectrometry is necessary to properly diagnosis transthyretin amyloidosis (ATTR) in patients with a history of MGUS or smoldering myeloma. PB58 (#110)

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.