Hypomorphic PKD1 Alleles Impact Disease Variability in Autosomal Dominant Polycystic Kidney Disease.
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ABSTRACT:
SUBMITTER: Gulati A
PROVIDER: S-EPMC10103195 | biostudies-literature | 2023 Mar
REPOSITORIES: biostudies-literature
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Hypomorphic PKD1 Alleles Impact Disease Variability in Autosomal Dominant Polycystic Kidney Disease.
Gulati Ashima A Dahl Neera K NK Hartung Erum A EA Clark Stephanie L SL Moudgil Asha A Goodwin Julie J Somlo Stefan S
Kidney360 20230301 3
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Project description:Autosomal dominant polycystic kidney disease is characterized by multiple cysts in both kidneys manifesting in adult life. In general, the disorder is caused by a pathogenic variant in one allele of PKD1 or PKD2 genes, while the other allele is normal. Pathogenic variants in both the alleles are rare and have variable phenotypes, from lethal or perinatal presentation to a mild form in later adulthood, depending on the type of variant. Here, we describe a proband with two variants (p.Thr1773Ile and p.Ala1871Thr in trans) in PKD1 gene, who presented with disease at age 24 years. Both the parents and one brother had a variant in one allele, the other being wild type only and had normal ultrasound findings. Segregation studies suggest that both the variants may act as "hypomorphic" or "incompletely penetrant" alleles and acting together resulted in haploinsufficiency of protein PC1 in renal cells, leading to cystogenesis in the proband. The consequences of the presence of two hypomorphic variants have been poorly documented in literature. We reviewed the few published cases having two hypomorphic variants and the data conform to the conclusions that we reached by study of the family described. It is emphasized that to resolve the significance of suspected hypomorphic variants, segregation studies in the parents and siblings are essential.
| S-EPMC6309388 | biostudies-literature
Project description:Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of kidney failure in adult life. Rarely, ADPKD can be diagnosed in utero or in infancy, and the genetic mechanism underlying such severe presentation has been shown to be related to reduced gene dosage. Biallelic PKD1 variants are often identified in early onset ADPKD, with one main pathogenic variant and a modifier hypomorphic variant showing an in trans configuration. We describe two unrelated individuals with early onset cystic kidney disease and unaffected parents, where a combination of next-generation sequencing of cystic genes including PKHD1, HNF1B and PKD1 allowed the identification of biallelic PKD1 variants. Furthermore, we review the medical literature in order to report likely PKD1 hypomorphic variants reported to date and estimate a minimal allele frequency of 1/130 for this category of variants taken as a group. This figure could help to orient genetic counseling, although the interpretation and the real clinical impact of rare PKD1 missense variants, especially if previously unreported, remain challenging.
| S-EPMC10298634 | biostudies-literature
Project description:ADPKD (Autosomal dominant polycystic kidney disease) is the most common inherited disorders and is characterized by growth of numerous cysts filled with fluid in the kidneys. Ultimately, it leads to kidney failure. The mutations of PKD1 and PKD2 account for approximately 85 and 15 percent of ADPKD, respectively. However, the mechanisms related to genetic mutation of PKD1 and PKD2 are still unclear. To investigate altered gene expression levels, Affymetrix microarray was performed using the kidney tissue from normal and ADPKD patients. Total RNAs were isolated from kidney of human normal (49 years old/ male) and ADPKD patients (62 years old/ male, 67 years old/ male) using NucleoSpin® RNA Kit (MACHEREY-NAGEL) according to the manufacturer’s instructions. We used tha Affymetrix GeneChip Human Gene 1.0 ST Array. Per RNA sample, 300 ng was used as the input into the Affymetrix procedure as recommended by the manufacturer's protocol.
2012-02-16 | E-GEOD-35831 | biostudies-arrayexpress
Project description:ADPKD (Autosomal dominant polycystic kidney disease) is the most common inherited disorders and is characterized by growth of numerous cysts filled with fluid in the kidneys. Ultimately, it leads to kidney failure. The mutations of PKD1 and PKD2 account for approximately 85 and 15 percent of ADPKD, respectively. However, the mechanisms related to genetic mutation of PKD1 and PKD2 are still unclear. To investigate altered gene expression levels, Affymetrix microarray was performed using the kidney tissue from normal and ADPKD patients.
2012-02-16 | GSE35831 | GEO
Project description:Autosomal dominant polycystic kidney disease (ADPKD) caused by PKD1 mutations is one of the most common hereditary disorders. However, the key pathological processes underlying cyst development and exacerbation in pre-symptomatic stages remain unknown, because rodent models do not recapitulate critical disease phenotypes, including disease onset in heterozygotes. Here, using CRISPR/Cas9, we generate ADPKD models with PKD1 mutations in cynomolgus monkeys. As in humans and mice, near-complete PKD1 depletion induces severe cyst formation mainly in collecting ducts. Importantly, unlike in mice, PKD1 heterozygote monkeys exhibit cyst formation perinatally in distal tubules, possibly reflecting the initial pathology in humans. Many monkeys in these models survive after cyst formation, and cysts progress with age. Furthermore, we succeed in generating selective heterozygous mutations using allele-specific targeting. We propose that our models elucidate the onset and progression of ADPKD, which will serve as a critical basis for establishing new therapeutic strategies, including drug treatments.
| S-EPMC6904451 | biostudies-literature
Project description:Prenatal forms of autosomal dominant polycystic kidney disease (ADPKD) are rare but can be recurrent in some families, suggesting a common genetic modifying background. Few patients have been reported carrying, in addition to the familial mutation, variation(s) in polycystic kidney disease 1 (PKD1) or HNF1 homeobox B (HNF1B), inherited from the unaffected parent, or biallelic polycystic kidney and hepatic disease 1 (PKHD1) mutations. To assess the frequency of additional variations in PKD1, PKD2, HNF1B, and PKHD1 associated with the familial PKD mutation in early ADPKD, these four genes were screened in 42 patients with early ADPKD in 41 families. Two patients were associated with de novo PKD1 mutations. Forty patients occurred in 39 families with known ADPKD and were associated with PKD1 mutation in 36 families and with PKD2 mutation in two families (no mutation identified in one family). Additional PKD variation(s) (inherited from the unaffected parent when tested) were identified in 15 of 42 patients (37.2%), whereas these variations were observed in 25 of 174 (14.4%, P=0.001) patients with adult ADPKD. No HNF1B variations or PKHD1 biallelic mutations were identified. These results suggest that, at least in some patients, the severity of the cystic disease is inversely correlated with the level of polycystin 1 function.
| S-EPMC4769188 | biostudies-literature
Project description:BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous disorder caused by mutations in at least two different loci. Prior to performing mutation screening, if DNA samples of sufficient number of family members are available, it is worthwhile to assign the gene involved in disease progression by the genetic linkage analysis.MethodsWe collected samples from 36 Slovene ADPKD families and performed linkage analysis in 16 of them. Linkage was assessed by the use of microsatellite polymorphic markers, four in the case of PKD1 (KG8, AC2.5, CW3 and CW2) and five for PKD2 (D4S1534, D4S2929, D4S1542, D4S1563 and D4S423). Partial PKD1 mutation screening was undertaken by analysing exons 23 and 31-46 and PKD2 .ResultsLod scores indicated linkage to PKD1 in six families and to PKD2 in two families. One family was linked to none and in seven families linkage to both genes was possible. Partial PKD1 mutation screening was performed in 33 patients (including 20 patients from the families where linkage analysis could not be performed). We analysed PKD2 in 2 patients where lod scores indicated linkage to PKD2 and in 7 families where linkage to both genes was possible. We detected six mutations and eight polymorphisms in PKD1 and one mutation and three polymorphisms in PKD2.ConclusionIn our study group of ADPKD patients we detected seven mutations: three frameshift, one missense, two nonsense and one putative splicing mutation. Three have been described previously and 4 are novel. Three newly described framesfift mutations in PKD1 seem to be associated with more severe clinical course of ADPKD. Previously described nonsense mutation in PKD2 seems to be associated with cysts in liver and milder clinical course.
| S-EPMC1434729 | biostudies-literature
Project description:BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is the most common form of inherited kidney disease that results in renal failure. ADPKD is a systemic disorder with cysts and connective tissue abnormalities involving many organs. ADPKD caused by mutations in PKD1 gene is significantly more severe than the cases caused by PKD2 gene mutations. The large intra-familial variability of ADPKD highlights a role for genetic background.Case presentationHere we report a case of ADPKD family initially appearing unlinked to the PKD1 or PKD2 loci and the influence of mosaicism and hypomorphic allele on the variability of the clinical course of the disease. A grandmother with the PKD1 gene mutation in mosaicism (p.Val1105ArgfsX4) and with mild clinical course of ADPKD (end stage renal failure at the age of 77) seemed to have ADPKD because of PKD2 gene mutation. On the other hand, her grandson had a severe clinical course (end stage renal disease at the age of 45) in spite of the early treatment of mild hypertension. There was found by mutational analysis of PKD genes that the severe clinical course was caused by PKD1 gene frameshifting mutation inherited from his father and mildly affected grandmother in combination with inherited hypomorphic PKD1 allele with described missense mutation (p.Thr2250Met) from his clinically healthy mother. The sister with two cysts and with PKD1 hypomorphic allele became the kidney donor to her severely affected brother.ConclusionWe present the first case of ADPKD with the influence of mosaicism and hypomorphic allele of the PKD1 gene on clinical course of ADPKD in one family. Moreover, this report illustrates the role of molecular genetic testing in assessing young related kidney donors for patients with ADPKD.
| S-EPMC3621255 | biostudies-literature
Project description:Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common hereditary kidney disease. We analysed PKD1 and PKD2, in a large cohort of 440 unrelated Italian patients with ADPKD and 203 relatives by direct sequencing and MLPA. Molecular and detailed phenotypic data have been collected and submitted to the PKD1/PKD2 LOVD database. This is the first large retrospective study in Italian patients, describing 701 variants, 249 (35.5%) already associated with ADPKD and 452 (64.5%) novel. According to the criteria adopted, the overall detection rate was 80% (352/440). Novel variants with uncertain significance were found in 14% of patients. Among patients with pathogenic variants, in 301 (85.5%) the disease is associated with PKD1, 196 (55.7%) truncating, 81 (23%) non truncating, 24 (6.8%) IF indels, and in 51 (14.5%) with PKD2. Our results outline the high allelic heterogeneity of variants, complicated by the presence of variants of uncertain significance as well as of multiple variants in the same subject. Classification of novel variants may be particularly cumbersome having an important impact on the genetic counselling. Our study confirms the importance to improve the assessment of variant pathogenicity for ADPKD; to this point databasing of both clinical and molecular data is crucial.
| S-EPMC4976333 | biostudies-literature
Project description:BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease. The disease is caused by mutations of the PKD1 (affecting roughly 85% of ADPKD patients) and PKD2 (affecting roughly 14% of ADPKD patients) genes, although in several ADPKD families, the PKD1 and/or PKD2 linkage was not found. Mutation analysis of the PKD1 gene is complicated by the presence of highly homologous genomic duplications of the first two thirds of the gene. METHODS: The direct detection of mutations in the non-duplicated region of the PKD1 gene was performed in 90 unrelated individuals, consisting of 58 patients with end-stage renal failure (manifesting before their 50th year of life) and 32 individuals from families where the disease was clearly linked to the PKD1 gene. Mutation screening was performed using denaturing gradient gel electrophoresis (DGGE). DNA fragments showing an aberrant electrophoretic banding pattern were sequenced. RESULTS: In the non-duplicated region of the PKD1 gene, 19 different likely pathogenic germline sequence changes were identified in 19 unrelated families/individuals. Fifteen likely pathogenic sequence changes are unique for the Czech population. The following probable mutations were identified: 9 nonsense mutations, 6 likely pathogenic missense mutations, 2 frameshifting mutations, one in-frame deletion and probable splice site mutation. In the non-duplicated region of the PKD1 gene, 16 different polymorphisms or unclassified variants were detected. CONCLUSION: Twenty probable mutations of the PKD1 gene in 90 Czech individuals (fifteen new probable mutations) were detected. The establishment of localization and the type of causal mutations and their genotype phenotype correlation in ADPKD families will improve DNA diagnosis and could help in the assessment of the clinical prognosis of ADPKD patients.
| S-EPMC2736583 | biostudies-literature