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A new tool to diagnose systemic amyloidoses

A recent article in the Blood journal proposes a new methodology for the differential diagnosis of systemic amyloidoses, a group of rare diseases characterized by protein deposits in organs and tissues. Thus, by using a type of microscopy, the immunoelectron microscopy, is possible to classify amyloidoses and determine which protein is involved to choose the most appropriate treatment. Dr. Carlos Fernández de Larrea, researcher of the 50/50 Program at the Hemato-Oncology IDIBAPS team and at the Amyloidosis and Myeloma Unit of Hospital Clínic, is the first author of this study, in which have participated scientists from the University of Pavia.

Amyloidoses are a very diverse group of diseases that occur when substance called amyloid –proteins- accumulates in organs and tissues. With an incidence of 8 people per million inhabitants per year, the evolution and prognosis of patients are determined by the location and type of deposit. There are over 30 different proteins that cause amyloidosis, either systemic or localized, but sometimes symptoms are common and very difficult to differentiate. It is crucial to know which is the protein responsible of the accumulation to provide adequate treatment.

Hitherto, to determine if a patient had amyloidosis, an abdominal fat puncture or a biopsy of the affected organ were performed. The resulting tissue was then stained to identify under the microscope the presence of amyloid. The problem is that this procedure does not allow characterizing the responsible protein and the alternative technologies are very expensive and not available in most institutions.

In this study, researchers analyzed samples from 745 patients with suspected amyloidosis by immunoelectron microscopy, a microscope technique that uses antibodies that specifically bind to each protein in order to identify it. They found that 423 patients had systemic amyloidosis and they were able to establish which protein was the responsible for the deposition in 99.5% of cases. The diagnosis was confirmed with other clinical tests an patients were administered the appropriate treatment in each case.

This study is the first to support the use of the immunoelectron microscopy for the diagnosis of systemic amyloidosis, which allows indentifying the protein that forms depositions in a more affordable way than other existing techniques and with the same precision degree. In addition, the puncture of abdominal fat consolidates as a quick and painless alternative to biopsies of affected organs for the diagnostic algorithm of this group of diseases.

Article reference:

A practical approach to the diagnosis of systemic amyloidoses

Fernández de Larrea C, Verga L, Morbini P, Klersy C, Lavatelli F, Foli A, Obici L, Milani P, Capello GL, Paulli M, Palladini G, Merlini G.

Blood. 2015 Apr 2;125(14):2239-44. doi: 10.1182/blood-2014-11-609883. Epub 2015 Jan 30.