A role for genetic susceptibility in sporadic focal segmental glomerulosclerosis
Haiyang Yu, … , Mark J. Daly, Andrey S. Shaw
Haiyang Yu, … , Mark J. Daly, Andrey S. Shaw
Published February 22, 2016
Citation Information: J Clin Invest. 2016;126(3):1067-1078. https://doi.org/10.1172/JCI82592.
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Research Article Nephrology

A role for genetic susceptibility in sporadic focal segmental glomerulosclerosis

Abstract

Focal segmental glomerulosclerosis (FSGS) is a syndrome that involves kidney podocyte dysfunction and causes chronic kidney disease. Multiple factors including chemical toxicity, inflammation, and infection underlie FSGS; however, highly penetrant disease genes have been identified in a small fraction of patients with a family history of FSGS. Variants of apolipoprotein L1 (APOL1) have been linked to FSGS in African Americans with HIV or hypertension, supporting the proposal that genetic factors enhance FSGS susceptibility. Here, we used sequencing to investigate whether genetics plays a role in the majority of FSGS cases that are identified as primary or sporadic FSGS and have no known cause. Given the limited number of biopsy-proven cases with ethnically matched controls, we devised an analytic strategy to identify and rank potential candidate genes and used an animal model for validation. Nine candidate FSGS susceptibility genes were identified in our patient cohort, and three were validated using a high-throughput mouse method that we developed. Specifically, we introduced a podocyte-specific, doxycycline-inducible transactivator into a murine embryonic stem cell line with an FSGS-susceptible genetic background that allows shRNA-mediated targeting of candidate genes in the adult kidney. Our analysis supports a broader role for genetic susceptibility of both sporadic and familial cases of FSGS and provides a tool to rapidly evaluate candidate FSGS-associated genes.

Authors

Haiyang Yu, Mykyta Artomov, Sebastian Brähler, M. Christine Stander, Ghaidan Shamsan, Matthew G. Sampson, J. Michael White, Matthias Kretzler, Jeffrey H. Miner, Sanjay Jain, Cheryl A. Winkler, Robi D. Mitra, Jeffrey B. Kopp, Mark J. Daly, Andrey S. Shaw

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Figure 2

Development of ES cells sensitized for FSGS.

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Development of ES cells sensitized for FSGS. (A) Identification of FSGS-...
(A) Identification of FSGS-sensitized ES cells. Our breeding strategy predicted that 1 of 8 embryos would have the correct genotype. ES cells were generated using standard approaches and genotyped for Cd2ap heterozygosity (upper panel), the NEFTA transgene (middle panel), and the Y chromosome (lower panel). (B) Laser-assisted injection generated mice with high chimerism. In the example shown, the ES cell line (agouti) was injected into 8-cell C57/BL6 (black) embryos. Compared with noninjected embryos (resulting in the 2 black mice shown on the bottom), all of the injected embryos generated pups that were close to being purely agouti. Injection of ES cells into C57/BL6 albino embryos resulted in completely agouti animals (not shown). (C) Mice generated from ES cells developed mild proteinuria after 4 months, with no DOX treatment. Fifteen mice were generated from the sensitized ES cells and treated with or without DOX in the drinking water. Urine was tested every month by measuring the albumin/creatinine ratios. Mice developed low-level proteinuria at 4 months of age, but the level of proteinuria was not affected by DOX treatment.