Transthyretin amyloidosis in a patient of Iranian-Jewish extraction: a second Israeli-Jewish case

Diagnostic Challenges and Solutions in Systemic Amyloidosis

Amyloidosis refers to a clinically heterogeneous group of disorders characterized by the extracellular deposition of amyloid proteins in various tissues of the body. To date, 42 different amyloid proteins that originate from normal precursor proteins and are associated with distinct clinical forms of amyloidosis have been described. Identification of the amyloid type is essential in clinical practice, since prognosis and treatment regimens both vary according to the particular amyloid disease. However, typing of amyloid protein is often challenging, especially in the two most common forms of amyloidosis, i.e., the immunoglobulin light chain amyloidosis and transthyretin amyloidosis. Diagnostic methodology is based on tissue examinations as well as on noninvasive techniques including serological and imaging studies. Tissue examinations vary depending on the tissue preparation mode, i.e., whether it is fresh-frozen or fixed, and they can be carried out by ample methodologies including immunohistochemistry, immunofluorescence, immunoelectron microscopy, Western blotting, and proteomic analysis. In this review, we summarize current methodological approaches used for the diagnosis of amyloidosis and discusses their utility, advantages, and limitations. Special attention is paid to the simplicity of the procedures and their availability in clinical diagnostic laboratories. Finally, we describe new methods recently developed by our team to overcome limitations existing in the standard assays used in common practice.

Late-onset and fast progressive neuropathy and cardiomyopathy in Val32Ala transthyretin gene mutation

More than 100 mutations of the transthyretin gene have been reported in autosomal dominant familial amyloid polyneuropathy. This rare disease causes severe motor and sensory disability, dysautonomia, and in some patients also cardiomyopathy. The diagnosis can be challenging mainly in sporadic adult patients showing clinical, laboratory, and neurophysiological findings overlapping other forms of chronic neuropathy. We describe the clinical features and course of a patient harboring the rare p.V32A (c.155T>C) variant that was previously described in only two patients and whose pathogenicity was unclear.

Free light chains in plasma of patients with light chain amyloidosis and non-amyloid light chain deposition disease. High proportion and heterogeneity of disulfide-linked monoclonal free light chains as pathogenic features of amyloid disease

Immunoglobulin light chain amyloidosis (AL) and non-amyloid light chain deposition disease (NALCDD) are different forms of protein aggregation disorders accompanied by a monoclonal gammopathy. Monoclonal free light chains (FLCs) are precursors of the pathological light chain tissue deposits that are fibrillar in AL and granular in NALCDD. However, direct biochemical examination of plasma FLC precursors, which would allow comparison and better understanding of these two diseases, is still lacking. In this study, we examined FLCs in plasma of patients with AL and NALCDD by employing separation on Sep-PaK C18 cartridges, micro-preparative electrophoresis, Western blotting and mass spectrometry. Comparative analysis of AL versus NALCDD and control plasma samples showed new evidence of increased level and heterogeneity of circulating disulfide-bound FLC species in AL. In addition to full length monomers comprising the disulfide-linked FLCs, the monoclonal disulfide-bound FLC fragments were typically revealed in AL plasma. We hypothesized that enhanced disulfide binding of FLCs in AL interferes with their normal clearance and metabolism, which in turn might play a role in amyloid formation. The applied methods might be useful to diagnose or predict the pathological form of the disease and shed light on the mechanisms involved in light chain aggregation in tissues.