Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is a common form of renal amyloidosis among Egyptians

Abstract

Large case series of renal amyloidosis subtypes have recently been published in the United States and Europe showing AL amyloidosis to be the predominant subtype in this part of the world. However, the most common subtypes of renal amyloidosis throughout the rest of the world are unknown. We present here the first large case series detailing the subtypes of renal amyloidosis among Egyptians. In this population, AA amyloidosis was the most common type of amyloidosis on renal biopsy at 48%. The newly described leukocyte chemotactic factor 2 amyloidosis (ALECT2) was the second most common type and represented nearly one-third of renal amyloid cases at 31%. AL accounted for only 20% of cases. The pathologic findings in ALECT2 cases were similar to those previously described in other case series. Thus ALECT2, which was initially thought to affect mainly Hispanics in the United States, appears to represent an important and likely underrecognized etiology of chronic kidney disease among Egyptians and probably in other ethnic groups around the world.

Figure 1

Laser microdissection/mass spectrometry in a patient with renal ALECT2 amyloidosis. (a-c) Renal parenchymal congophilic amyloid deposits from a patient with ALECT2 are visualized under fluorescent light and marked for microdissection. Three separate microdissections (LMD#1, LMD#2, and LMD#3) are analyzed. (d) Scaffold software display of amyloid-associated proteins identified within the deposits by liquid chromatography/tandem mass spectrometry. The three columns on the right represent the separate micro-dissected samples run in triplicate. The numbers within the columns represent the total number of mass spectra corresponding to the identified protein and the color of the box reflects the probability that the spectra are correctly assigned to the identified protein (all >95%). In this case, the presence of abundant spectra for serum amyloid P and apolipoprotein E is indicative of amyloid, whereas the presence of abundant spectra for leukocyte cell-derived chemotaxin 2 (LECT2) establishes the identity of the amyloid as ALECT2.

Figure 2

Leukocyte chemotactic factor 2 amyloidosis. (a and b) Uptake of Congo red by glomerular and interstitial amyloid deposits (a) with green birefringence upon (b) polarization (original magnification × 200). (c) Extensive amorphous deposits of LECT2 amyloid in the glomeruli and interstitial compartments (hematoxylin and eosin; original magnification × 200). (d) Reactivity of glomerular and interstitial amyloid deposits with an anti-LECT2 antibody (immunoperoxidase technique, × 200).