Abstract
<b><i>Background:</i></b> Amyloidosis includes a diverse group of rare diseases characterized by the misfolding of native or mutant proteins, leading to extracellular accumulation in various organs. While 42 proteins have been identified to date, their distribution differs between systemic and localized forms. <b><i>Summary:</i></b> Mass spectrometry analysis of tissue samples in the USA shows immunoglobulin light chain (AL) amyloidosis as the most prevalent systemic type, followed by transthyretin (ATTR). Heart and kidney involvements are common. Although there are 14 recognized types of kidney-related amyloidosis, clinicopathologic studies in the USA have identified 11 types, with AL amyloidosis being the most prevalent cause of kidney involvement. <b><i>Key Messages:</i></b> This review focuses on AL, AA, and ATTR amyloidosis due to their common systemic presentations. Recent US-based clinicopathologic studies challenge conventional beliefs that toxicity is primarily driven by amyloid deposition and highlight the role of the complement pathway. Diagnostic methods, particularly mass spectrometry, are crucial for accurate typing. Treatment strategies vary depending on the underlying type, with AL amyloidosis primarily targeting plasma cell clones, AA amyloidosis addressing underlying inflammation with systemic therapies, and ATTR amyloidosis focusing on ATTR stabilization or gene silencing.