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(A) From left to right, Kidney biopsy hematoxylin and eosin stain, original magnification x 400. The glomerulus shows a lobular architecture and capillary loops with increased thickness and double contours. There is endocapillary and mesangial proliferation with mononuclear cells. On the left, an arteriole shows moderate sclerosis. Kidney biopsy electron microscopy, uranyl acetate-lead citrate stain, original magnification x 6000. The glomerular capillary loop shows massive, confluent, subepithelial electron-dense deposits with spike formation from the basement membrane mimicking stage II of a membranous pattern of injury. There are several scattered, small electron-dense deposits in subendothelial areas. The endothelium is very swollen and contains multiple tubulo-reticular inclusions. (B) Kidney biopsy immunofluorescence with antibodies against IgG, C3 and C1q original magnification x 200. Both glomeruli show coarse and fine granular deposits in the mesangium and peripheral capillary loops. There are also some granular deposits at the tubular basement membranes. Immunofluorescence studies were also positive for C3 and C1q granular deposits, mainly at the mesangium, but also present on segments in a subendothelial location. (C) Family pedigree and Sanger tracings of patient SLC7A7 variants.
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F1
He developed septic shock and disseminated intravascular coagulation with multisystem failure, leading ultimately to his death 45 days after admission. 3 days postmortem, the final renal biopsy report demonstrated an immune complex-mediated glomerulonephritis (Figures 1A,B).
Gene map showing the frequency and clinical manifestations associated with different SLCA7A variants described in the reviewed literature.
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F2
ES also showed that both parents were carriers for SLC7A7 variants; the mother was heterozygous for Leu334Arg and the father was heterozygous for Arg159Cys variants respectively, in accordance with Mendelian expectations for an autosomal recessive disease trait (Figure 2).