Kidney Week

Abstract: SA-PO570

Recessive Mutation in CD2AP Causes Focal Segmental Glomerulosclerosis in Humans and in Mice

Session Information

• Noncystic Mendelian Diseases
  November 04, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Genetic Diseases of the Kidney

• 802 Non-Cystic Mendelian Diseases

Authors

• Takano, Tomoko, McGill University Health Centre, Montreal, Quebec, Canada

Tomoko Takano,

• Aoudjit, Lamine, McGill University Health Centre, Montreal, Quebec, Canada

Lamine Aoudjit,

• Baldwin, Cindy, McGill University Health Centre, Montreal, Quebec, Canada

Cindy Baldwin,

• El andalousi, Jasmine, Montreal Children's Hospital, Montreal, Quebec, Canada

Jasmine El andalousi,

• Muhtadie, Lina, Lakeshore General Hospital, Montreal, Quebec, Canada

Lina Muhtadie,

• Gupta, Indra R., Montreal Children's Hospital, Montreal, Quebec, Canada

Indra R. Gupta,

Background

CD2-associated protein (CD2AP) is an adaptor protein expressed in podocytes. Cd2ap^-/- mice develop early-onset severe nephrotic syndrome and die at 6 weeks old, while Cd2ap^+/- mice show susceptibility to insults and glomerulosclerosis at 9 months old. However, only a few patients have been described with mutations in CD2AP.

Methods

Whole exome sequencing (WES) was performed on genomic DNA. C57B6 mouse-derived ES cells were electroporated with Cas9, two guide sequences and a donor oligo to allow CRISPR-mediated insertion of 4 base-pairs into the Cd2ap gene. One ES clone with the desired insertion was used to generate chimeric mice that were crossed to C57B6 mice for germline transmission.

Results

Three siblings (2 males and 1 female) born of consanguineous parents developed FSGS in their teens and progressed to ESRD by 20 years of age. WES identified an insertion of 4 nucleotides in the CD2AP gene, causing a frame shift at Ser198, resulting in a stop codon (p.Ser198fs). All three siblings were homozygous for the mutation, while the unaffected father was heterozygous. Mother’s DNA was not available. When heterozygous mice carrying the insertion were bred, wild-type (WT), heterozygous, and homozygous mice were born at the expected Mendelian frequency. By 2-3 weeks, homozygous mice showed heavy albuminuria, glomerulosclerosis, tubular atrophy, and interstitial leukocyte infiltration. By 4-6 weeks, histological changes worsened and were accompanied by elevated serum creatinine and BUN and hypoalbuminemia. These changes were not seen in heterozygotes or WT. Homozygous mice died at 7-8 weeks, likely from kidney failure.

Conclusion

CRISPR/Cas9 gene editing has been utilized to generate a mouse model with a recessive mutation in Cd2ap, p.Ser198fs that results in FSGS, nephrotic syndrome, and kidney failure in mice. The results prove that this recessive mutation in CD2AP is causal in human FSGS.

Funding

• Government Support - Non-U.S.