Autosomal recessive polycystic kidney disease (ARPKD) is the most common inherited childhood-onset renal disease, with underlying ciliopathy, and varies widely in clinical severity. The aim of this study was to describe the most severe form of ARPKD, with a fatal clinical course, and its association with mutations in polycystic kidney and hepatic disease 1 (fibrocystin) (PKHD1). Clinical, imaging, pathological, and molecular genetic findings were reviewed in patients prenatally affected with ARPKD and their families.Five unrelated Korean families, including 9 patients, were analyzed. Among the 9 patients, 2 fetuses died in utero, 6 patients did not survive longer than a few days, and 1 patient survived for 5 months with ventilator support and renal replacement therapy. A total of 6 truncating mutations (all nonsense) and 4 missense mutations were detected in a compound heterozygous state, including 4 novel mutations. The most severe phenotypes were shared among all affected patients in each family, irrespective of mutation types.Our data suggest a strong genotype-phenotype relationship in ARPKD, with minimal intra-familial heterogeneity. These findings are important for informing future reproductive planning in affected families.

To investigate the therapeutic potential of tesevatinib (TSV), a unique multi-kinase inhibitor currently in Phase II clinical trials for autosomal dominant polycystic kidney disease (ADPKD), in well-defined rodent models of autosomal recessive polycystic kidney disease (ARPKD).

Autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in PKHD1, encoding fibrocystin/polyductin (FPC). Severe disease occurs in perinates. Those who survive the neonatal period face a myriad of comorbidities, including systemic and portal hypertension, liver fibrosis, and hepatosplenomegaly. The goal here was to uncover therapeutic strategies for ARPKD.

Autosomal recessive polycystic kidney disease (ARPKD), characterized by progressive cystic degeneration of the kidneys and congenital hepatic fibrosis (CHF), is the most common childhood onset ciliopathy, with an estimated frequency of 1 in 20,000 births. It is caused by mutations in PKHD1. The carrier frequency for ARPKD in the general population is estimated at 1 in 70. Given the recessive inheritance pattern, individuals who are heterozygous for PKHD1 mutations are not expected to have clinical findings. We performed ultrasound (USG) evaluations on 110 parents from 64 independent ARPKD families and identified increased medullary echogenicity in 6 (5.5%) and multiple small liver cysts in 10 parents (9%). All ARPKD parents with these abnormal imaging findings were asymptomatic; kidney and liver function tests were unremarkable. Complete sequencing of PKHD1 in the 16 ARPKD parents with abnormal imaging confirmed the mutation transmitted to the proband, but did not reveal any other pathogenic variants. Our data suggest that carrier status for ARPKD is a predisposition to polycystic liver disease and renal involvement associated with increased medullary echogenicity on USG. Whether some of these individuals become symptomatic as they age remains to be determined.

The prognosis of autosomal recessive polycystic kidney disease is known to correlate with genotype. The presence of two truncating mutations in the PKHD1 gene encoding the fibrocystin protein is associated with neonatal death while patients who survive have at least one missense mutation. To determine relationships between genotype and renal and hepatic abnormalities we correlated the severity of renal and hepatic histological lesions to the type of PKHD1 mutations in 54 fetuses (medical pregnancy termination) and 20 neonates who died shortly after birth. Within this cohort, 55.5% of the mutations truncated fibrocystin. The severity of cortical collecting duct dilatations, cortical tubule and glomerular lesions, and renal cortical and hepatic portal fibrosis increased with gestational age. Severe genotypes, defined by two truncating mutations, were more frequent in patients of less than 30 weeks gestation compared to older fetuses and neonates. When adjusted to gestational age, the extension of collecting duct dilatation into the cortex and cortical tubule lesions, but not portal fibrosis, was more prevalent in patients with severe than in those with a non-severe genotype. Our results show the presence of two truncating mutations of the PKHD1 gene is associated with the most severe renal forms of prenatally detected autosomal recessive polycystic kidney disease. Their absence, however, does not guarantee survival to the neonatal period.

In the present study, we report on a couple who underwent prenatal genetic diagnosis for autosomal recessive polycystic kidney disease (ARPKD).

There is a high prevalence of rare genetic disorders in the Middle East, and their study provides unique clinical and genetic insights. Autosomal recessive polycystic kidney disease (ARPKD) is one of the leading causes of kidney and liver-associated morbidity and mortality in Oman. We describe the clinical and genetic profile of cohort of ARPKD patients.

Autosomal recessive polycystic kidney disease (ARPKD) a rare genetic disorder, described by formation of cysts in the kidney. A targeted customized sequencing of genes implicated in ARPKD phenotype was performed to identify candidate variants using the Ion torrent PGM next-generation sequencing. The results identified likely pathogenic disease causing variants during the validation process. Four potential pathogenic variants [c.4870C>T, p.(Arg1624Trp)], [c.5725C>T, p.(Arg1909Trp)], c.1736C>T, p.(Thr579Met)] and [(c.10628T>G), p.(Leu3543Trp)] were observed in PKHD1 gene among 12 out of 18 samples. The rest of the patient samples also showed few variants in ADPKD (Autosomal Dominant Polycystic Kidney Disease) disease causing genes PKD1 and PKD2 i.e. [c.12433G>A, p.(Val4145Ile)] and [c.1445T>G, p.(Phe482Cys)], respectively. All causative variants were validated by capillary sequencing, confirming the presence of a novel homozygous variants [c.10628T>G, p.(Leu3543Trp)] found in exon 61 of a male proband. All potentially deleterious variants identified in PKHD1, PKD1, and PKD2 gene, also exhibited pathologically or clinically significance based on the computational predictions involved in predicting the impact of non-synonymous SNPs (nsSNPs) on protein function such as Sorting Intolerant From Tolerant (SIFT) and Polymorphism Phenotyping (PolyPhen2). SIFT classified 50% of our nsSNPs as "deleterious", while PolyPhen2 identified 45% of our nsSNPs as "Probably damaged" and the results from both programs were largely complementary. Taken together, these results suggest that the NGS strategies provide a fast, accurate and cost-effective molecular diagnostic tool for identifying mutations in targeted genes sequence analysis.

(1) Background: Autosomal recessive polycystic kidney disease (ARPKD) is a rare ciliopathy characterized by progressively enlarged kidneys with fusiform dilatation of the collecting ducts. Loss-of-function mutations in the PKHD1 gene, which encodes fibrocystin/polyductin, cause ARPKD; however, an efficient treatment method and drug for ARPKD have yet to be found. Antisense oligonucleotides (ASOs) are short special oligonucleotides which function to regulate gene expression and alter mRNA splicing. Several ASOs have been approved by the FDA for the treatment of genetic disorders, and many are progressing at present. We designed ASOs to verify whether ASOs mediate the correction of splicing further to treat ARPKD arising from splicing defects and explored them as a potential treatment option. (2) Methods: We screened 38 children with polycystic kidney disease for gene detection using whole-exome sequencing (WES) and targeted next-generation sequencing. Their clinical information was investigated and followed up. The PKHD1 variants were summarized and analyzed, and association analysis was carried out to analyze the relationship between genotype and phenotype. Various bioinformatics tools were used to predict pathogenicity. Hybrid minigene analysis was performed as part of the functional splicing analysis. Moreover, the de novo protein synthesis inhibitor cycloheximide was selected to verify the degraded pathway of abnormal pre-mRNAs. ASOs were designed to rescue aberrant splicing, and this was verified. (3) Results: Of the 11 patients with PKHD1 variants, all of them exhibited variable levels of complications of the liver and kidneys. We found that patients with truncating variants and variants in certain regions had a more severe phenotype. Two splicing variants of the PKHD1 genotypes were studied via the hybrid minigene assay: variants c.2141-3T>C and c.11174+5G>A. These cause aberrant splicing, and their strong pathogenicity was confirmed. We demonstrated that the abnormal pre-mRNAs produced from the variants escaped from the NMD pathway with the use of the de novo protein synthesis inhibitor cycloheximide. Moreover, we found that the splicing defects were rescued by using ASOs, which efficiently induced the exclusion of pseudoexons. (4) Conclusion: Patients with truncating variants and variants in certain regions had a more severe phenotype. ASOs are a potential drug for treating ARPKD patients harboring splicing mutations of the PKHD1 gene by correcting the splicing defects and increasing the expression of the normal PKHD1 gene.

Previous studies have suggested that some children with autosomal recessive polycystic kidney disease (ARPKD) have growth impairment out of proportion to their degree of chronic kidney disease (CKD). The objective of this study was to systematically compare growth parameters in children with ARPKD to those with other congenital causes of CKD in the chronic kidney disease in Children (CKiD) prospective cohort study.

Mutation of the Cys1 gene underlies the renal cystic disease in the Cys1cpk/cpk (cpk) mouse that phenocopies human autosomal recessive polycystic kidney disease (ARPKD). Cystin, the protein product of Cys1, is expressed in the primary apical cilia of renal ductal epithelial cells. In previous studies, we showed that cystin regulates Myc expression via interaction with the tumor suppressor, necdin. Here, we demonstrate rescue of the cpk renal phenotype by kidney-specific expression of a cystin-GFP fusion protein encoded by a transgene integrated into the Rosa26 locus. In addition, we show that expression of the cystin-GFP fusion protein in collecting duct cells down-regulates expression of Myc in cpk kidneys. Finally, we report the first human patient with an ARPKD phenotype due to homozygosity for a deleterious splicing variant in CYS1. These findings suggest that mutations in Cys1/CYS1 cause an ARPKD phenotype in mouse and human, respectively, and that the renal cystic phenotype in the mouse is driven by overexpression of the Myc proto-oncogene.

ARPKD is associated with mutations in the PKHD1 gene on chromosome 6p12. Most cases manifest peri-/neonatally with a high mortality rate in the first month of life while the clinical spectrum of surviving patients is much more variable than generally perceived.

Transcription factor Ap2b (TFAP2B), an AP-2 family transcription factor, binds to the palindromic consensus DNA sequence, 5'-GCCN3-5GGC-3'. Mice lacking functional Tfap2b gene die in the perinatal or neonatal period with cystic dilatation of the kidney distal tubules and collecting ducts, a phenotype resembling autosomal recessive polycystic kidney disease (ARPKD). Human ARPKD is caused by mutations in PKHD1, DZIP1L, and CYS1, which are conserved in mammals. In this study, we examined the potential role of TFAP2B as a common regulator of Pkhd1 and Cys1. We determined the transcription start site (TSS) of Cys1 using 5' Rapid Amplification of cDNA Ends (5'RACE); the TSS of Pkhd1 has been previously established. Bioinformatic approaches identified cis-regulatory elements, including two TFAP2B consensus binding sites, in the upstream regulatory regions of both Pkhd1 and Cys1. Based on reporter gene assays performed in mouse renal collecting duct cells (mIMCD-3), TFAP2B activated the Pkhd1 and Cys1 promoters and electromobility shift assay (EMSA) confirmed TFAP2B binding to the in silico identified sites. These results suggest that Tfap2b participates in a renal epithelial cell gene regulatory network that includes Pkhd1 and Cys1. Disruption of this network impairs renal tubular differentiation, causing ductal dilatation that is the hallmark of recessive PKD.

Autosomal recessive polycystic kidney disease (ARPKD) is a rare but potentially lethal genetic disorder typically characterized by diffuse renal microcysts. Clinical trials for patients with ARPKD are not currently possible due to the absence of sensitive measures of ARPKD kidney disease progression and/or therapeutic efficacy.

Autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in the polycystic kidney and hepatic disease (PKHD1) gene encoding the protein fibrocystin/polyductin. The aim of our study was to produce a mouse model of ARPKD in which there was no functional fibrocystin/polyductin to study the pathophysiology of cystic and fibrocystic disease in renal and non-renal tissues. Exon 2 of the gene was deleted and replaced with a neomycin resistance cassette flanked by loxP sites, which could be subsequently removed by Cre-lox recombinase. Homozygous Pkhd1(del2/del2) mice were viable, fertile and exhibited hepatic, pancreatic, and renal abnormalities. The biliary phenotype displayed progressive bile duct dilatation, resulting in grossly cystic and fibrotic livers in all animals. The primary cilia in the bile ducts of these mutant mice had structural abnormalities and were significantly shorter than those of wild-type (WT) animals. The Pkhd1(del2/del2) mice often developed pancreatic cysts and some exhibited gross pancreatic enlargement. In the kidneys of affected female mice, there was tubular dilatation of the S3 segment of the proximal tubule (PT) starting at about 9 months of age, whereas male mice had normal kidneys up to 18 months of age. Inbreeding the mutation onto BALBc/J or C57BL/6J background mice resulted in females developing PT dilatation by 3 months of age. These inbred mice will be useful resources for studying the mechanisms underlying the pathogenesis of ARPKD.

The Sanger sequencing of patients with recessive polycystic kidney disease is challenging due to the length and heterogeneous mutational spectrum of the PKHD1 gene. Next generation sequencing (NGS) might thus be of special interest to search for PKHD1 mutations. The study involved a total of 22 patients with autosomal recessive polycystic kidney disease (ARPKD) and 8 parents of non-available ARPKD patients. Five pools of 6 samples each were sequenced with the Personal Genome Machine (PGM, Ion Torrent). For each DNA pool, a total of 109 fragments that covered the entire PKHD1 coding sequence were amplified in only two tubes followed by library preparation and NGS with the PGM. To validate the technique, each pool contained the DNA of at least one patient with known mutation. The putative mutations identified in each pool were confirmed and assigned to specific individuals through Sanger sequencing. All but one of the 109 amplicons were successfully read, and we identified the two PKHD1 mutations in 11 of the ARPKD cases, one mutation in 9 patients, and no mutation in only 2 patients. Six of the 8 parents from non-available patients were mutation carriers. The reported procedure would facilitate the large scale analysis of PKHD1 with a significant reduction in cost and labor.

Autosomal recessive polycystic kidney disease (ARPKD) is a hereditary fibrocystic disease that primarily involves the kidneys and hepatobiliary tract. The polycystic kidney and hepatic disease 1 (PKHD1) gene is the only gene implicated in ARPKD. The present study aimed to identify PKHD1 mutations causing ARPKD in a Chinese family. A couple that underwent prenatal genetic diagnosis for ARPKD and their families were recruited for the present study. Genomic DNA was collected from the amniotic fluid of the fetus (proband) and from peripheral blood of all other available family members. Targeted exome sequencing was performed on the couple and the proband, followed by direct Sanger sequencing on other family members and normal controls to confirm candidate pathogenic variants. Two novel compound heterozygous mutations in the PKHD1 gene were identified as causative in the proband, including maternally inherited c.2876C>T (p.Ser959Phe) and paternally inherited c.5772C>A (p.Phe1924Leu). Each mutation was found to co‑segregate with the ARPKD phenotype in the family. Other family members either carried one of the two mutations or lacked both mutations, while the mutations were not found in 576 ethnically matched normal controls. Therefore, two novel compound heterozygous PKHD1 mutations were implicated in causing ARPKD in a Han Chinese family. The results expand the mutation spectrum of PKHD1 that leads to ARPKD, which may improve genetic counseling and prenatal diagnosis for families with ARPKD.

Human autosomal recessive polycystic kidney disease (ARPKD) produces kidneys which are massively enlarged due to multiple cysts, hypertension, and congenital hepatic fibrosis characterized by dilated bile ducts and portal hypertension. The PCK rat is an orthologous model of human ARPKD with numerous fluid-filled cysts caused by stimulated cellular proliferation in the renal tubules and hepatic bile duct epithelia, with interstitial fibrosis developed in the liver. We previously reported that a peroxisome proliferator activated receptor (PPAR)-γ full agonist ameliorated kidney and liver disease in PCK rats. Telmisartan is an angiotensin receptor blocker (ARB) used widely as an antihypertensive drug and shows partial PPAR-γ agonist activity. It also has nephroprotective activity in diabetes and renal injury and prevents the effects of drug-induced hepatotoxicity and hepatic fibrosis. In the present study, we determined whether telmisartan ameliorates progression of polycystic kidney and fibrocystic liver disease in PCK rats. Five male and 5 female PCK and normal control (+/+) rats were orally administered 3 mg/kg telmisartan or vehicle every day from 4 to 20 weeks of age. Treatment with telmisartan decreased blood pressure in both PCK and +/+ rats. Blood levels of aspartate amino transferase, alanine amino transferase and urea nitrogen were unaffected by telmisartan treatment. There was no effect on kidney disease progression, but liver weight relative to body weight, liver cystic area, hepatic fibrosis index, expression levels of Ki67 and TGF-β, and the number of Ki67- and TGF-β-positive interstitial cells in the liver were significantly decreased in telmisartan-treated PCK rats. Therefore, telmisartan ameliorates congenital hepatic fibrosis in ARPKD, possibly through the inhibition of signaling cascades responsible for cellular proliferation and interstitial fibrosis in PCK rats. The present results support the potential therapeutic use of ARBs for the treatment of fibrocystic liver disease in ARPKD patients.

Sorting and maintenance of the EGF receptor on the basolateral surface of renal epithelial cells is perturbed in polycystic kidney disease and apical expression of receptors contributes to severity of disease. The goal of these studies was to understand the molecular basis for EGF receptor missorting using a well-established mouse model for the autosomal recessive form of the disease. We have discovered that multiple basolateral pathways mediate EGF receptor sorting in renal epithelial cells. The polycystic kidney disease allele in this model, Bicc1, interferes with one specific EGF receptor pathway without affecting overall cell polarity. Furthermore one of the pathways is regulated by a latent basolateral sorting signal that restores EGF receptor polarity in cystic renal epithelial cells via passage through a Rab11-positive subapical compartment. These studies give new insights to possible therapies to reconstitute EGF receptor polarity and function in order to curb disease progression. They also indicate for the first time that the Bicc1 gene that is defective in the mouse model used in these studies regulates cargo-specific protein sorting mediated by the epithelial cell specific clathrin adaptor AP-1B.

PKHD1, the gene mutated in autosomal recessive polycystic kidney disease (ARPKD)/congenital hepatic fibrosis (CHF), is an exceptionally large and complicated gene that consists of 86 exons and has a number of alternatively spliced transcripts. Its longest open reading frame contains 67 exons that encode a 4074 amino acid protein called fibrocystin or polyductin. The phenotypes caused by PKHD1 mutations are similarly complicated, ranging from perinatally-fatal PKD to CHF presenting in adulthood with mild kidney disease. To date, more than 300 mutations have been described throughout PKHD1. Most reported cohorts include a large proportion of perinatal-onset ARPKD patients; mutation detection rates vary between 42% and 87%. Here we report PKHD1 sequencing results on 78 ARPKD/CHF patients from 68 families. Differing from previous investigations, our study required survival beyond 6 months and included many adults with a CHF-predominant phenotype. We identified 77 PKHD1 variants (41 novel) including 19 truncating, 55 missense, 2 splice, and 1 small in-frame deletion. Using computer-based prediction tools (GVGD, PolyPhen, SNAP), we achieved a mutation detection rate of 79%, ranging from 63% in the CHF-predominant group to 82% in the remaining families. Prediction of the pathogenicity of missense variants will remain challenging until a functional assay is available. In the meantime, use of PKHD1 sequencing data for clinical decisions requires caution, especially when only novel or rare missense variants are identified.