Use of patient derived urine renal epithelial cells to confirm pathogenicity of PKHD1 alleles
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RESEARCH ARTICLE
Open Access
Use of patient derived urine renal epithelial cells to confirm pathogenicity of PKHD1 alleles Elisa Molinari1, Shalabh Srivastava1, Rebecca M. Dewhurst1 and John A. Sayer1,2,3*
Abstract Background: PKHD1 is the main genetic cause of autosomal recessive polycystic kidney disease (ARPKD), a hereditary hepato-renal fibrocystic disorder which is the most important cause of end-stage renal disease during early childhood. ARPKD can also present in adulthood with milder phenotypes. In this study, we describe a 24-year-old woman with atypical polycystic kidney, no family history of renal disease and no obvious extra-renal manifestations who was referred for genetic investigation. Methods: We used a combination of next generation sequencing, Sanger sequencing and RNA and microscopy studies performed on urine-derived renal epithelial cells (URECs) to provide a genetic diagnosis of ARPKD. Results: A next generation sequencing panel of cystic ciliopathy genes allowed the identification of two heterozygous sequence changes in PKHD1 (c.6900C > T; p.(Asn2300=) and c.7964A > C; p.(His2655Pro)). The pathogenicity of the synonymous PKHD1 variant is not clear and requires RNA studies, which cannot be carried out efficiently on RNA extracted from proband blood, due to the low expression levels of PKHD1 in lymphocytes. Using URECs as a source of kidney-specific RNA, we show that PKHD1 is alternatively spliced around exon 43, both in control and proband URECs. The variant p.(Asn2300=) shifts the expression ratio in favour of a shorter, out-of-frame transcript. To further study the phenotypic consequence of these variants, we investigated the ciliary phenotype of patient URECs, which were abnormally elongated and presented multiple blebs along the axoneme. Conclusions: We confirm the power of URECs as a tool for functional studies on candidate variants in inherited renal disease, especially when the expression of the gene of interest is restricted to the kidney and we describe, for the first time, ciliary abnormalities in ARPKD patient cells. Keywords: Urine, ARPKD, Synonymous variant, Cilia
Background Autosomal recessive polycystic kidney disease (ARPKD; MIM # 263200) is a hereditary hepato-renal fibrocystic disorder, with an estimated incidence of 1:20,000 live births. Affected individuals typically present in utero * Correspondence: [email protected] 1 Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK 2 Renal Services, The Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK Full list of author information is available at the end of the article
with enlarged, echogenic kidneys and oligohydramnios. 30–50% of ARPKD patients die shortly after birth from respiratory insufficiency due to pulmonary hypoplasia. Children who survive the perinatal period have varied clinical presentations. Approximately one half develop end-stage renal failure. Cysts in the kid
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