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Abstract: SA-PO573

Trio Whole Exome Sequencing Analysis Reveals PRPF8 as a Potential Ciliopathy Candidate Gene Phenocopying Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)

Session Information

  • Genetic Diseases: Diagnosis
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

  • 1102 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Merz, Lea Maria, Department of Pediatrics, University Hospital, Leipzig, Saxony, Germany
  • Carrocci, Tucker Joe, Department of Biochemistry, University of Wisconsin - Madison, Madison, Wisconsin, United States
  • Mertens, Nils David, Department of Pediatric Nephrology, Boston Children’s Hospital & Harvard Medical School, Boston, Massachusetts, United States
  • Buerger, Florian, Department of Pediatric Nephrology, Boston Children’s Hospital & Harvard Medical School, Boston, Massachusetts, United States
  • Reutter, Heiko M., Department of Neonatology, University Hospital, Erlangen, Bavaria, Germany
  • Hoskins, Aaron, Department of Biochemistry, University of Wisconsin - Madison, Madison, Wisconsin, United States
  • Shril, Shirlee, Department of Pediatric Nephrology, Boston Children’s Hospital & Harvard Medical School, Boston, Massachusetts, United States
  • Hildebrandt, Friedhelm, Department of Pediatric Nephrology, Boston Children’s Hospital & Harvard Medical School, Boston, Massachusetts, United States
Background

Congenital abnormalities of the kidneys and urinary tract (CAKUT) represent the most frequent birth defect. The discovery of ≥45 monogenic causes of CAKUT in humans has generated novel insights into its pathogenesis. PRPF8 is a core component of the spliceosome and was recently shown to be localized at the distal end of the mother centriole (Shen, J Cell Biol. 3;221(1):e202105092, 2022). It functions as receptor for the linear ubiquitin assembly complex, facilitating the removal of CP110 from the mother centriole and promoting ciliogenesis.

Methods

We performed whole exome sequencing in 136 trios of children with CAKUT and identified de novo variants in 38 different genes. To identify the most likely pathogenic variants, we ranked those 38 de novo variants using the following criteria: constraint and prediction scores, absence from the gnomAD control database, number of additional de novo variants, and whether a mouse model with CAKUT existed. Since CAKUT-linked mutations occurred at positions that are highly conserved between yeast and human spliceosomes, we are using S. cerevisiae (growth and ACT1-CUP1 reporter assays) as a model system to test their impact on aspects of the splicing reaction.

Results

Following those criteria, PRPF8 scored highest as a potential new candidate gene for CAKUT. We identified two additional CAKUT families with heterozygous de novo missense variants (Reutter, Current Genomics 16(999):1-1, 2015, Lei, 40(10):1290-1299, 2020) and 8 further heterozygous missense mutations that were inherited or of unknown mode of inheritance. All three de novo variants are positioned in highly conserved regions within the linker and endonuclease domains, including one amino acid residue that was previously shown to impact the catalytic steps of splicing in S. cerevisiae (human PRPF8 residue R1681). Using splicing assays, we found that PRP8 mutants do not impact the splicing at the consensus splice sites. Two mutants showed an altered splicing effect at the non-consensus splice with a potential inhibition of the exon ligation.

Conclusion

We generated initial evidence that PRPF8 mutations may represent a novel ciliopathy gene, phenocopying CAKUT.

Funding

  • NIDDK Support