Genotype-Renal Function Correlation in Type 2 Autosomal Dominant Polycystic Kidney Disease
Riccardo Magistroni*,,
Ning He*,
Kairong Wang*,
Robin Andrew*,
Ann Johnson,
Patricia Gabow,
Elizabeth Dicks,
Patrick Parfrey,
Roser Torra,
Jose L. San-Millan¶,
Eliecer Coto#,
Marjan van Dijk@,
Martijn Breuning**,
Dorien Peters**,
Nadja Bogdanova,
Giulia Ligabue,
Alberto Albertazzi,
Nick Hateboer,
Kyproula Demetriou¶¶,
Alkis Pierides¶¶,
Constantinos Deltas##,
Peter St. George-Hyslop*,
David Ravine and
York Pei*
*Division of Genomic Medicine, University Health Network, Toronto, Canada; Renal Division, University of Colorado Health Sciences Center, Denver, CO; Division of Nephrology, Memorial University, St. John’s, Newfoundland, Canada; Division of Nephrology, Fundacio Puigvert, Barcelona, Spain; ¶Unidad de Genetica Molecular, Hospital Ramon y Cajal, Madrid, Spain; #Instituto Reina Sofia de Investigaciones Nephrologicas, Hospital Central de Asturias, Oviedo, Spain; @Academisch Ziekenhuis and **Afdeling Anthropogenetica Rijksuniversiteit Leiden, Leiden, the Netherlands; Institut Fur Humangenetik, Westfalische Wilheims-Universitat, Munster, Germany; Division of Nephrology, University of Modena and Reggio Emilia, Modena, Italy; Institute of Medical Genetics, University Hospital of Wales, Cardiff, UK; ¶¶Department of Nephrology, Nicosia General Hospital, Cyprus; and ##Department of Biological Sciences, University of Cyprus and Department of Molecular Genetics, Cyprus Institute of Neurology and Genetics, Cyprus.
Correspondence to Dr. York Pei, Division of Nephrology and Genomic Medicine, University Health Network, 13 EN-228, 200 Elizabeth Street, Toronto, Ontario, Canada M5G 2C4. Phone: 416-340-4257; Fax: 416-340-4999;
ABSTRACT. Autosomal dominant polycystic kidney disease (ADPKD)is a common Mendelian disorder that affects approximately 1in 1000 live births. Mutations of two genes, PKD1 and PKD2,account for the disease in approximately 80 to 85% and 10 to15% of the cases, respectively. Significant interfamilial andintrafamilial renal disease variability in ADPKD has been welldocumented. Locus heterogeneity is a major determinant for interfamilialdisease variability (i.e., patients from PKD1-linked familieshave a significantly earlier onset of ESRD compared with patientsfrom PKD2-linked families). More recently, two studies havesuggested that allelic heterogeneity might influence renal diseaseseverity. The current study examined the genotype-renal functioncorrelation in 461 affected individuals from 71 ADPKD familieswith known PKD2 mutations. Fifty different mutations were identifiedin these families, spanning between exon 1 and 14 of PKD2. Most(94%) of these mutations were predicted to be inactivating.The renal outcomes of these patients, including the age of onsetof end-stage renal disease (ESRD) and chronic renal failure(CRF; defined as creatinine clearance 50 ml/min, calculatedusing the Cockroft and Gault formula), were analyzed. Of allthe affected individuals clinically assessed, 117 (25.4%) hadESRD, 47 (10.2%) died without ESRD, 65 (14.0%) had CRF, and232 (50.3%) had neither CRF nor ESRD at the last follow-up.Female patients, compared with male patients, had a later meanage of onset of ESRD (76.0 [95% CI, 73.8 to 78.1] versus 68.1[95% CI, 66.0 to 70.2] yr) and CRF (72.5 [95% CI, 70.1 to 74.9]versus 63.7 [95% CI, 61.4 to 66.0] yr). Linear regression andrenal survival analyses revealed that the location of PKD2 mutationsdid not influence the age of onset of ESRD. However, patientswith splice site mutations appeared to have milder renal diseasecompared with patients with other mutation types (P < 0.04by log rank test; adjusted for the gender effect). Considerablerenal disease variability was also found among affected individualswith the same PKD2 mutations. This variability can confoundthe determination of allelic effects and supports the notionthat additional genetic and/or environmental factors may modulatethe renal disease severity in ADPKD. E-mail: york.pei@uhn.on.ca
Autosomal dominant polycystic kidney disease (ADPKD [MIM 173900])is the most common hereditary kidney disorder, with an incidenceof approximately 1 in 1000 live births, and accounts for approximately5 to 8% of end-stage renal disease (ESRD) (1,2). It is characterizedby the progressive formation and enlargement of renal cysts,typically leading to chronic renal failure by late middle age.Other manifestations of this disorder, such as cyst formationin non-renal organs, cardiac valvular defects, colonic diverticulosis,and intracranial arterial aneurysms, accompany the renal diseasevariably. Linkage studies in ADPKD families have documentedgenetic heterogeneity (3,4), and at least two disease genes(PKD1 [MIM 601313] on chromosome 16p13.3 and PKD2 [MIM 173910]on chromosome 4q13–23) have been identified and characterized(5–7). A rare putative third disease gene (PKD3 [MIM 600666])has been implicated by the identification of a small numberof families unlinked to the known gene loci (8,9). Mutationsof PKD1 and PKD2 account for the disease in approximately 80to 85% and approximately 10 to 15% of Caucasian ADPKD families,respectively (1,10). Polycystins 1 and 2, the gene productsof PKD1 and PKD2, are transmembrane proteins that share sequencehomology and are currently thought to be part of a novel signalingpathway that regulates intracellular calcium (11–13).Polycystin 1 is predicted to have a receptor-like structureand may be involved in cell-cell and/or cell-matrix interaction(12,13). In contrast, polycystin 2 shares significant homologyto and can function as a cation ion channel subunit, with nonselectivepermeability (12–14). Both proteins have been shown tointeract in vitro through their cytoplasmic region, with polycystin1 likely functioning as a regulator of polycystin 2 (11–14).
Disease progression of ADPKD is highly variable, with age atonset of ESRD ranging from childhood to old age (1). Geneticlocus heterogeneity is a major determinant for interfamilialdisease variability: patients from PKD1-linked families havea significantly earlier onset of ESRD or death when comparedwith patients from PKD2-linked families (median age: 53 [95%CI, 51.2 to 54.8] versus 69 [95% CI, 66.9 to 71.3] yr) (15).More recently, two studies have suggested that allelic heterogeneityin ADPKD might also influence renal disease severity. In thefirst study, patients with mutations in the 3' half of PKD1had milder renal disease than patients with mutations in the5' half of the gene (16). In the second study, patients withmutations in the 3' half of PKD2 had milder composite scoresfor renal complications (i.e., presence or absence of hypertension,hematuria, renal calculi, and urinary tract infection) thanpatients with mutations in the 5' half of the gene (17). However,correlation of renal function with genotype data has not beenassessed in the patients with PKD2 mutations. In the currentstudy, we report a pooled analysis of genotype-renal functioncorrelation in 461 affected individuals from 71 ADPKD familieswith known PKD2 mutations.
Study Patients
The clinical and genetic data of 461 affected members from 71ADPKD families with known germline PKD2 mutations were analyzed.The PKD2 mutations in 50 families have been previously described(17–25), and the remaining mutations from 21 familiesare reported here for the first time. The diagnosis of ADPKDin the patients and at-risk individuals from each study familywas established using well-established ultrasound-based criteria(26). Any affected individual with a concomitant renal disease(e.g., diabetic nephropathy) was excluded from this study. Thedemographic, clinical, and laboratory data (including serumcreatinine and/or creatinine clearance) were obtained from allthe participants after obtaining informed consent. All the researchprotocols used in the study have been approved by the institutionalreview boards of all the participating centers.
Definitions of Primary Renal Outcome
Two renal disease outcomes were used in this study. End-stagerenal disease (ESRD) is defined as severe chronic renal failurewith a serum creatinine value 500 uM (or 5.7 mg/dl) or therequirement of renal replacement therapy (chronic dialysis orrenal transplantation). Chronic renal failure (CRF) is definedas moderately severe chronic renal failure with a calculatedcreatinine clearance 50 ml/min per 1.73 m2 by the formula ofCockroft and Gault (27). The study subjects were classifiedas hypertensive if their systolic or diastolic BP exceeded the95th percentile predicted for age and gender or if they requiredanti-hypertensive treatment.
PKD2 Mutational Analyses
DNA isolation and mutation screening methods have been previouslydetailed (17–24). Single-stranded conformational polymorphism(SSCP), heteroduplex analysis (HA), or direct sequencing wasemployed to screen all 15 exons and their flanking intronicsequences of PKD2 (28) for PKD2 mutations in one definitivelyaffected individual from each study family. Whenever possible,segregation of a specific mutation with ADPKD was tested withineach family by SSCP, HA, restriction-digestion, or allele-specificoligonucleotide hybridization. All nonconservative missensechanges identified were also tested to determine whether theywere present in at least 100 normal chromosomes. Both strandsof the PCR templates containing any variants were sequencedby the dideoxy terminator method using an ABI 373 or 377 DNASequencer (Applied Biosystems). PKD2 mutations were considered5' mutations if they were located in the first half of the openreading frame (nucleotides 1 to 1452), or 3' mutations if theywere located in the second half of the open reading frame (nucleotides1453 to 2904). Gross deletion, nonsense, and frameshift mutationswere classified as truncating mutations, and missense and splicemutations were analyzed separately.
Statistical Analyses
Time from birth to ESRD (i.e., renal death) was computed bythe product-limit (i.e., Kaplan-Meier) method of survival analysis.To assess the differences in renal survival (i.e., freedom fromESRD) between specific patient groups of interest, a two-sidedlog-rank test was used. Additionally, time to ESRD plus deathwas analyzed as an additional outcome measure. The effects ofthe covariates (i.e., gender and hypertension) on renal survivalwere tested using the univariate Cox proportional hazards modelor the log-rank test for continuous or categorical variables,respectively (29). Linear regression analysis was also performedto assess the influence of the position of the PKD2 mutationson the age of onset of ESRD and CRF separately. The runningaverage of the age of onset of ESRD and CRF in Figure 2 wasbased on the best fitting cubic spline function of the age versusnucleotide relationship. For the linear regression and renalsurvival analyses, the results based on ESRD alone or ESRD plusdeath were not significantly different. Thus, only the resultsbased on ESRD alone will be presented because this outcome measureprovides a more accurate assignment of renal survival. All theanalyses were performed using the SPSS version 11.0.1 (SPSS,Chicago, IL) and PRISM version 3.0 (GraphPad Software, Inc.San Diego, CA) statistical packages.
Figure 2. Renal survival (i.e., absence of ESRD) analysis. The probability of renal survival differs significantly between female (n = 221) than male (n = 174) patients with PKD2 mutations (2 = 27.9; P < 0.00005 by log-rank test). On average, female patients developed ESRD 8 yr later than male patients with PKD2 mutations.
Clinical Characteristics of Study Patients
We analyzed the clinical and genetic data of 461 affected individuals(44.2% male; 55.8% female) from 71 families in which the germlinePKD2 mutations were characterized. Overall, 117 of these affectedindividuals (25.4%) had ESRD, 47 died without ESRD (10.2%),65 (14.0%) had CRF, and 232 (50.3%) had neither CRF nor ESRDat the last follow-up. Although ruptured intracranial arterialaneurysm was the primary cause of death in at least seven affectedindividuals who died without ESRD, the cause of death was notavailable for the remaining 40 patients. BP information wasavailable in 103 of 182 individuals with either ESRD or CRF,and hypertension was present in 68 (66%) of these 103 individuals.Figure 1 shows the frequency distribution of the study patentsby their age of onset of ESRD, CRF, and death. Typical of type2 ADPKD, the mode of distribution of these events occurred ata relatively late age (i.e., age range of 60 to 79 yr). However,considerable renal disease variability (e.g., age range of onsetof ESRD: 40 to 88 yr) was also evident between individual patients.In general, female patients had milder renal disease than malepatients (i.e., the mean age of onset of ESRD and CRF was 76.0[95% CI, 73.8 to 78.1] versus 68.1 [95% CI, 66.0 to 70.2] and72.5 [95% CI, 70.1 to 74.9] versus 63.7 [95% CI, 61.4 to 66.0]yr, respectively). The renal survival (i.e., absence of ESRD)curves also differed significantly between the two gender groups(Figure 2).
Figure 1. Frequency distribution of age of onset of end-stage renal disease (ESRD), death (without ESRD), and chronic renal failure (CRF) in the study patients. Typical of type 2 ADPKD, the mode of distribution of these events occurred at a relatively late age (age range, 60 to 79 yr). However, considerable renal disease variability (age range of onset of ESRD, 40 to 88 yr) was also evident between individual patients.
Spectrum of PKD2 Mutations
Fifty different mutations from 71 families were included inthe current study (Table 1). These mutations spanned the entirePKD2, with the exception of exons 3 and 15, for which no mutationshave been reported thus far. Among these 71 families, 27 (38.0%)had nonsense mutations, 27 (38.0%) had frameshift mutations,12 (16.9%) had splice site mutations, 4 (5.6%) had missensemutations, and one (1.5%) had a complete deletion of PKD2. Thefour missense mutations (A356P; W414G; C632R; R807Q) includedin this study all involved nonconservative amino acid changes,segregated only in the affected members of the same family andwere not observed in at least 100 normal chromosomes. Severalmutations recurred in apparently unrelated families. Of interest,a single nucleotide deletion or insertion of a polyadenosinetract (2152–2159delA and 2152–2159insA) on exon11 accounted for frameshift mutations in six families. Additionally,the same splice site mutation in exon 5 (i.e. IVS5+1GA) wasresponsible for the mutation in three Spanish and two Canadianfamilies. The frequencies of various clinical events (i.e.,ESRD, CRF, and death) in the patients with different types ofPKD2 mutations are detailed in Table 2.
Table 2. Distribution of patients with different clinical outcomes by PKD2 mutation typesa
Genotype-Renal Function Correlation
We analyzed the correlation between the age of onset of ESRDand the nucleotide position of the PKD2 mutation in the studypatients (upper panel of Figure 3). Linear regression analysisshowed a correlation coefficient (r) of 0.109 (r2 = 0.012),and the slope of the regression line did not differ significantlyfrom zero (slope value: 0.001 [95% CI, -0.001 to 0.004]). Similarly,we analyzed the correlation between the age of onset of CRFand the nucleotide position of the PKD2 mutation in the studypatients (upper panel of Figure 3). Linear regression analysisshowed a correlation coefficient (r) of 0.036 (i.e., r2 = 0.001),and the slope did not differ significantly from zero (slopevalue: -0.0004 [95% CI, -0.004 to 0.003]). These results remainedunchanged when the correlation was stratified by gender. Atthe last follow-up, 232 study patients had not developed eitherCRF or ESRD and a plot of their age by the position of the PKD2mutations is shown in the lower panel of Figure 3. Considerablerenal disease variability was noted among patients with thesame mutations. For example, five patients (i.e., boxed in theupper panel of Figure 3) whose mutations clustered around thenucleotide position of 1000 to 1500 of the open reading frameof PKD2, had atypically severe renal disease (i.e., ESRD before50 yr of age). However, on close inspection they representedcases at one end of the spectrum of disease severity among patientswith the same PKD2 mutations (Figure 4). In contrast, severalpatients, who did not have CRF even after 70 yr of age (lowerpanel of Figure 3), represented cases with exceptionally milddisease.
Figure 3. Linear regression analysis of renal disease severity and nucleotide position of PKD2 mutations in the study patients. The slope of the regression line for patients with ESRD (blue square) and CRF (red diamond) did not significantly differ from zero (upper panel). Considerable disease variability was noted among patients with the same mutations. For example, five patients with four different PKD2 mutations (boxed in the upper panel) had atypically severe disease with ESRD before 50 yr of age. However, these patients represented discordant cases among patients with the same PKD2 mutation (see Figure 4). In contrast, several patients (green triangles in lower panel), who did not have CRF even after 70 yr of age, represented cases with exceptionally mild disease.
Figure 4. Significant renal disease variability among patients with the same PKD2 mutations. Five patients (see Figure 3), whose mutations clustered around the nucleotide position of 1000 to 1500 of the open reading frame of PKD2, had atypically severe renal disease. However, they represented discordant cases among patients with the same PKD2 mutations. One or more older patients with the same mutations had mild renal disease typical of type 2 ADPKD (square denotes ESRD; diamond denotes CRF).
We also analyzed the renal survival of the study patients bythe types (i.e., missense, truncating, and splice site) as wellas location (i.e., 5' or nt 1–1452 versus 3' or nt 1453–2904)of their PKD2 mutations (Table 3; Figure 5). We found that neitherthe types (P = 0.26 by log-rank test; upper panel) nor the location(P = 0.78 by log-rank test; lower panel) of the PKD2 mutationsinfluence the renal survival of our patients. Gender was a significantdeterminant of renal survival; we therefore also repeated thesurvival analyses using univariate proportional-hazards modelsto include gender as a covariate. In the gender-adjusted analysis,we found that patients with splice site mutations appeared tohave a more favorable renal survival compared with patientswith other mutation types (i.e., P = 0.046; Figure 6). On theother hand, the 5' and 3' location of the PKD2 mutations didnot influence renal survival. Hypertension (i.e., presence orabsence), included as a covariate in univariate proportional-hazardsmodels, did not change our findings.
Figure 5. Renal survival (i.e., absence of ESRD) of the study patients by the types (i.e., missense, truncating, or splice site mutations) and location (i.e., 5' half versus 3' half) of their PKD2 mutations. Neither the types (P = 0.26 by log-rank test; upper panel) nor the location (P = 0.78 by log-rank test; lower panel) of the mutations appeared to influence the renal survival of the study patients.
Figure 6. Gender-adjusted renal survival analysis suggests a more favorable outcome in patients with splice site mutations. Univariate Cox proportionate hazards analysis with gender included as a covariate indicates that patients with splice site mutations may have a more favorable renal survival (i.e., absence of ESRD) than patients with missense and truncating mutations (P = 0.046).
In this study, we have examined the genotype-renal functioncorrelation in a large cohort of patients from families withknown PKD2 mutations. Consistent with the published literature(3,15), we found in our study patients a late age of onset ofESRD (i.e., mean age of 72 yr) and a strong gender effect onrenal disease severity (i.e., P < 0.00005 by log-rank test).The mutations identified in the study families, spanning betweenexons 1 and 14, also covered the entire spectrum of PKD2 mutationsreported to date (25). Several of these mutations are of particularinterest (Table 1). For example, the four missense mutations(A356P; W414G; C632R; R807Q) included in this study all involvednonconservative amino acid changes, segregated only in the affectedmembers of the family, and were not observed in the normal population.They are also predicted to change within the mutant polycystin2–specific amino acids that are evolutionarily conservedbetween different organisms (data not shown). However, structural-functionalanalyses have not been performed on these mutations. Nonetheless,W414G, by virtue of its location within the polycystin domain,may disrupt the dimerization of polycystin 2 with itself andwith polycystin 1 (12,14). In contrast, C632R and R807Q, locatedin the pore region and endoplasmic reticulum retention domain,may disrupt the channel function of polycystin 2 (11,14). Itis also conceivable that some of these missense changes mayin fact result in aberrant splicing, as recently described inanother PKD2 mutation: nt A2657G (30). Of the recurring mutations,two involving an insertion or deletion of a polyadenosine tract(i.e., 2152–2159delA and 2152–2159insA) are of interest.These mutations were observed in six apparently unrelated familiesfrom different geographical regions, suggesting that the polyadenosinetract (p(A)8: nt 2152–2159) on exon 11 is a regional hotspot within PKD2 that predisposes to both germline (Table 1)and somatic mutations (31), presumably by "slipped strand mispairing"(20).
The location but not the types of PKD1 mutations has been recentlyreported to influence renal disease severity in a large cohortof patients with type 1 ADPKD (16). Specifically, patients withmutations localized to the 5' half of PKD1 had an earlier onsetof ESRD compared with patients with mutations localized to the3' half of the gene (i.e., median age of onset of ESRD: 53 versus56 yr, respectively; P = 0.025). However, this effect is weakcompared with the locus effect between PKD1 and PKD2 mutations(15). Given that most PKD1 mutations are predicted to be protein-truncating,these data have led to the suggestion that mutations in the3'-end of this gene may result in partially functional geneproducts (16). In the current study, we were unable to detecta position effect in our patients by either linear regressionor renal survival analyses. With a large patient sample sizeand adjustment for the gender effect, we believe that our analysesare robust. Most PKD2 mutations are also predicted to truncatethe C'-terminus of polycystin 2; it therefore appears that theloss of the coil-coil interaction region with polycystin 1 (i.e.,the most distal C'-terminal functional domain so far identified)may be sufficient to completely inactivate the mutant protein(11,12,14). Recent human (31–33) and knockout mouse (34,35)studies have suggested that a common mechanism for individualcyst formation in ADPKD results from the inactivation of PKD1or PKD2 within an epithelial cell, through germline and somaticmutations. Our data are consistent with this classical two-hitmodel of cystogenesis in ADPKD and suggest that most PKD2 mutationsare completely inactivating.
In contrast to the lack of correlation between the mutationtypes and renal disease severity seen in type 1 ADPKD (16),we found that our patients with PKD2 splice site mutations appearedto have milder renal disease compared with patients with othermutation types (P = 0.046 by log-rank test; Figure 6). Amongthe families with the splice site mutations, one family (family61; IVS12–7TA; Table 1) had notably mild disease, withfive elderly affected individuals developing only CRF at age70, 71, 79, 80, and 83 yr, respectively. It is conceivable thatcertain splice site mutations may be "leaky," so that low levelsof a normal protein product can still be generated by the mutantallele. Should this be the case, a threshold model for polycystin2 within individual epithelial cells of patients with such mutationsmay provide an additional mechanism for the cystogenic process.Under this model, individual cells with low levels of a functionalpolycystin may be triggered into a cystogenic pathway by localstresses and other stochastic factors (36,37). Alternatively,it is possible that the above observation may be spurious, giventhe borderline statistical association and the presence of asignificant "modifier effect" (see below).
The most definitive conclusion of our study is that significantrenal disease variability exists among the patients with thesame PKD2 mutations (Figures 1 and 3). Within individual families,we have observed both elderly patients with very mild renaldisease and younger patients with ESRD (Figure 4). This is consistentwith the finding of significant renal disease variability withinfamilies with PKD1-linkage (38) and among patients with thesame PKD1 mutations (16). Taken together, these data suggestthe existence of a modifier effect for ADPKD (17,38,39). Recentstudies have shown that the phenotypic variability of a numberof Mendelian disorders is in fact complex because of the existenceand interaction of genetic and environmental modifiers (40).Some recent examples include cystic fibrosis (41) and Hirschsprungdisease (42), in which one or more modifier loci/genes havebeen implicated from both animal models and patients. Indeed,several population-based studies have recently examined thepolymorphic variants of the angiotensin-converting enzyme (ACE)(16,43–46) and endothelial nitric oxide synthase (eNOS)(47,48) genes as modifiers of renal disease progression in ADPKD.However, these studies are limited by their research study designand small patient sample size, and they have produced conflictingresults. Future studies using a family-based research design(49) and properly-powered patient sample size will be requiredto dissect the individual components of this modifier effect.The identification of specific genetic and environmental modifierswill have important relevance for individual patient prognosticationand mechanism-based therapy in ADPKD.
Acknowledgments
We are indebted to all the participating members of the ADPKDfamilies. Supported by grants from Polycystic Kidney ResearchFoundation, Canadian Institutes of Health Research (MOP53324),and Kidney Foundation of Canada (Y.P.); Department of Healthand Human Services, Public Health Service, USA, and GeneralClinical Research Centers Program of the Division of ResearchResources, National Institutes of Health, USA (A.J. and P.G.);Cyprus Kidney Association (C.D.).
Hughes J, Ward CJ, Peral B, Aspinwall R, Clark K, San Millan JL, Gamble V, Harris PC: The polycystic kidney disease 1 (PKD1) gene encodes a novel protein with multiple cell recognition domains. Nat Genet 10: 151–160, 1995[Medline]
International Polycystic Kidney Disease Consortium: Polycystic kidney disease: The complete structure of the PKD1 gene and its protein. Cell 81: 289–298, 1995[CrossRef][Medline]
Mochizuki T, Wu G, Hayashi T, Xenophontos SL, Veldhuisen B, Saris JJ, Reynolds DM, Cai Y, Gabow PA, Pierides A, Kimberling WJ, Breuning MH, Deltas CC, Peters DJ, Somlo S: PKD2, a gene for polycystic kidney disease that encodes an integral membrane protein. Science 272: 1339–1342, 1996[Abstract]
Daoust MC, Reynolds DM, Bichet DG, Somlo S: Evidence for a third genetic locus for autosomal dominant polycystic kidney disease. Genomics 25: 733–736, 1995[CrossRef][Medline]
Paterson A, Pei Y: A third gene for autosomal dominant polycystic kidney disease? Kidney Int 54: 1759–1761, 1998[CrossRef][Medline]
Peters DJ, Sandkuijl LA: Genetic heterogeneity of polycystic kidney disease in Europe. Contrib Nephrol 97: 128–139, 1992[Medline]
Somlo S, Ehrlich B: Human disease: Calcium signaling in polycystic kidney disease. Curr Biol 11: R356–R360, 2001[CrossRef][Medline]
Igarashi P, Somlo S: Genetics and pathogenesis of polycystic kidney disease. J Am Soc Nephrol 13: 2384–2398, 2002[Free Full Text]
Koulen P, Cai Y, Geng L, Maeda Y, Nishimura S, Witzgall R, Ehrlich BE, Somlo S: Polycystin-2 is an intracellular calcium release channel. Nat Cell Biol 4, 191–197, 2002
Hateboer N, v Dijk MA, Bogdanova N, Coto E, Saggar-Malik AK, San Millan JL, Torra R, Breuning M, Ravine D: Comparison of phenotypes of polycystic kidney disease types 1 and 2. European PKD 1:PKD 2 Study Group. Lancet 353: 103–107, 1999[CrossRef][Medline]
Rossetti S, Burton S, Strmecki L, Pond G, San Millan J, Zerres K, Barratt TM, Ozen S, Torres V, Bergstralh EJ, Winearls C, Harris PC: The position of the polycystic kidney disease 1 gene mutation correlates with the severity of renal disease. J Am Soc Nephrol 13: 1230–7, 2002[Abstract/Free Full Text]
Hateboer N, Veldhuisen B, Peters D, Breuning MH, San-Millan JL, Bogdanova N, Coto E, van Dijk MA, Afzal AR, Jeffery S, Saggar-Malik AK, Torra R, Dimitrakov D, Martinez I, de Castro SS, Krawczak M, Ravine D: Location of mutations within the PKD2 gene influences clinical outcome. Kidney Int 57: 1444–1451, 2000[CrossRef][Medline]
Veldhuisen B, Saris JJ, de Haij S, Hayashi T, Reynolds DM, Mochizuki T, Elles R, Fossdal R, Bogdanova N, van Dijk MA, Coto E, Ravine D, Norby S, Verellen-Dumoulin C, Breuning MH, Somlo S, Peters DJ: A spectrum of mutations in the second gene for autosomal dominant polycystic kidney disease. Am J Hum Genet 61: 547–555, 1997[Medline]
Viribay M, Hayashi T, Telleria D, Mochizuki T, Reynolds DM, Alonso R, Lens XM, Moreno F, Harris PC, Somlo S, San Millan JL: Novel stop and frameshifting mutations in the autosomal dominant polycystic kidney disease 2 gene. Hum Genet 101: 229–234, 1997[CrossRef][Medline]
Pei Y, He N, Wang K, Kasenda M, Paterson AD, Chan G, Liang Y, Roscoe J, Brissenden J, Hefferton D, Parfrey P, Somlo S, St George-Hyslop P: A spectrum of mutations in the polycystic kidney disease-2 gene from eight Canadian kindreds. J Am Soc Nephrol 9: 1853–1860, 1998[Abstract]
Aguiari G, Manzati E, Penolazzi L, Micheletti F, Augello G, Vitali ED, Cappelli G, Cai Y, Reynolds D, Somlo S, Piva R, del Senno L: Mutations in autosomal dominant polycystic kidney disease 2 gene: Reduced expression of PKD2 protein in lymphoblastoid cells. Am J Kidney Dis 33: 880–885, 1999[Medline]
Demetriou K, Tziakouri C, Anninou K, Eleftheriou A, Koptides M, Nicolaou A, Deltas C, Pierides A: Autosomal dominant polycystic kidney disease-type 2 Ultrasound, genetic and clinical correlations. Nephrol Dial Transplant 15: 205–211, 2000[Abstract/Free Full Text]
Iglesias DM, Telleria D, Viribay M, Herrera M, Bernath VA, Kornblihtt AR, Martin RS, Millan JL: A novel frameshift mutation (2436insT) produces an immediate stop codon in the autosomal dominant polycystic kidney disease 2 gene. Nephrol Dial Transplant 15: 477–480, 2000[Abstract/Free Full Text]
Torra R, Badenas C, Perez-Oller L, Luis J, Millan S, Nicolau C, Oppenheimer F, Mila M, Darnell A: Increased prevalence of polycystic kidney disease type 2 among elderly polycystic patients. Am J Kidney Dis 36: 728–734, 2000[Medline]
Deltas CC: Mutations of the human polycystic kidney disease 2 (PKD2) gene. Hum Mutat 18: 13–24, 2001[CrossRef][Medline]
Cockcroft DW, Gault MH: Prediction of creatinine clearance from serum creatinine. Nephron 16: 31–41, 1976[Medline]
Hayashi T, Mochizuki T, Reynolds D, Wu Y, Cai Y, Somlo S: Characterization of the exon structure of the Polycystic Kidney Disease2 gene. Genomics 44: 131–136, 1997[CrossRef][Medline]
Cox DR: Regression models and life-tables. J Royal Statist Soc 34: 187–220, 1972
Reynolds D, Hayashi T, Cai YQ, Veldhuisen B, Watnick T, Lens X, Mochizuki T, Qian F, Maeda Y, Li L, Fossdal R, Coto E, Wu GQ, Breuning M, Germino G, Peters D, Somlo S: Aberrant splicing in the PKD2 gene as a cause of polycystic kidney disease. J Am Soc Nephrol 10: 2342–2351, 1999[Abstract/Free Full Text]
Watnick T, He N, Wang KW, Liang Y, Parfrey P, Hefferton D, St. George-Hyslop P, Germino G, Pei Y: Somatic mutations in PKD1 in ADPKD2 tissue suggest a possible pathogenic role of trans-heterozygous mutations. Nature Genet 25: 143–144, 2000[CrossRef][Medline]
Qian F, Watnick TJ, Onuchic LF, Germino GG: The molecular basis of focal cyst formation in human autosomal dominant polycystic kidney disease type 1. Cell 87: 979–987, 1996[CrossRef][Medline]
Koptides M, Hadjimichael C, Koupepidou P, Pierides A, Constantinou Deltas C: Germinal and somatic mutations in the PKD2 gene of renal cysts in autosomal dominant polycystic kidney disease. Hum Mol Genet 8: 509–513, 1999[Abstract/Free Full Text]
Lu W, Shen X, Pavlova A, Lakkis M, Ward CJ, Pritchard L, Harris PC, Genest DR, Perez-Atayde AR, Zhou J: Comparison of Pkd1-targeted mutants reveals that loss of polycystin-1 causes cystogenesis and bone defects. Hum Mol Genet 10: 2385–2389, 2001[Abstract/Free Full Text]
Wu GQ, D’Agati V, Cai Y, Markowitz G, Park JH, Reynolds D, Maeda Y, Le TC, Hou H, Kucherlapati R, Edelmann W, Somlo S: Somatic inactivation of Pkd2 results in polycystic kidney disease. Cell 93: 177–188, 1998[CrossRef][Medline]
Wilkie A: The molecular basis of genetic dominance. J Med Genet 31: 89–98, 1994[Abstract/Free Full Text]
Pei Y, Paterson AD, Wang KR, He N, Hefferton D, Watnick T, Germino GG, Parfrey P, Somlo S, St. George-Hyslop P: Bilineal disease and trans-heterozygotes in autosomal dominant polycystic kidney disease. Am J Hum Genet 68: 355–363, 2001[CrossRef][Medline]
Hateboer N, Lazarou LP, Williams AJ, Holmans P, Ravine D: Familial phenotype differences in PKD1. Kidney Int 56: 34–40, 1999[CrossRef][Medline]
Pei Y: A "two-hit" model of cystogenesis in autosomal dominant polycystic kidney disease? Trends Mol Med 7: 151–156, 2001[CrossRef][Medline]
Dipple KM, McCabe ER: Modifier genes convert "simple" Mendelian disorders to complex traits. Mol Genet Metab 71: 43–50, 2000[CrossRef][Medline]
Zielenski J, Corey M, Rozmahel R, Markiewicz D, Aznarez I, Casals T, Larriba S, Mercier B, Cutting GR, Krebsova A, Macek M Jr, Langfelder-Schwind E, Marshall BC, DeCelie-Germana J, Claustres M, Palacio A, Bal J, Nowakowska A, Ferec C, Estivill X, Durie P, Tsui LC: Detection of a cystic fibrosis modifier locus for meconium ileus on human chromosome 19q13. Nat Genet 22: 128–129, 1999[CrossRef][Medline]
Carrasquillo MM, McCallion AS, Puffenberger EG, Kashuk CS, Nouri N, Chakravarti A: Genome-wide association study and mouse model identify interaction between RET and EDNRB pathways in Hirschsprung disease. Nat Genet 32: 237–244, 2002[CrossRef][Medline]
Baboolal K, Ravine D, Daniels J, Williams N, Holmans P, Coles GA, Williams JD: Association of the angiotensin I converting enzyme gene deletion polymorphism with early onset of ESRF in PKD1 adult polycystic kidney disease. Kidney Int 52: 607–613, 1997[Medline]
Perez-Oller L, Torra R, Bandenas C, Mila M, Darnell A: Influence of the angiotensin converting enzyme polymorphism in the progression of renal failure in autosomal dominant polycystic kidney disease. Am J Kidney Dis 34: 273–278, 1999[Medline]
van Dijk MA, Breuning MH, Peters DJ, Chang PC: The ACE insertion/deletion polymorphism has no influence on progression of renal function loss in autosomal dominant polycystic kidney disease. Nephrol Dial Transplant 15: 836–839, 2000[Abstract/Free Full Text]
Schiavello T, Burke V, Bogdanova N, Jasik P, Melsom S, Boudville N, Robertson K, Angelicheva D, Dworniczak B, Lemmens M, Horst J, Todorov V, Dimitrakov D, Sulowicz W, Krasniak A, Stompor T, Beilin L, Hallmayer J, Kalaydjieva L, Thomas M: Angiotensin-converting enzyme activity and the ACE Alu polymorphism in autosomal dominant polycystic kidney disease. Nephrol Dial Transplant 16: 2323–2327, 2001[Abstract/Free Full Text]
Persu A, Stoenoiu MS, Messiaen T, Davila S, Robino C, El-Khattabi O, Mourad M, Horie S, Feron O, Balligand JL, Wattiez R, Pirson Y, Chauveau D, Lens XM, Devuyst O: Modifier effect of ENOS in autosomal dominant polycystic kidney disease. Hum Mol Genet 11: 229–241, 2002[Abstract/Free Full Text]
Walker D, Consugar M, Slezak J, Rossetti S, Torres VE, Winearls CG, Harris PC: The ENOS polymorphism is not associated with severity of renal disease in polycystic kidney disease 1. Am J Kidney Dis 41: 90–94, 2003[CrossRef][Medline]
Martin ER, Monks SA, Warren LL, Kaplan NL: A test for linkage and association in general pedigrees: the pedigree disequilibrium test. Am J Hum Genet 67: 146–154, 2000[CrossRef][Medline]
Received for publication November 27, 2002.
Accepted for publication January 20, 2003.
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Top
Abstract
Introduction
50 ml/min, calculated using the Cockroft and Gault formula), were analyzed. Of all the affected individuals clinically assessed, 117 (25.4%) had ESRD, 47 (10.2%) died without ESRD, 65 (14.0%) had CRF, and 232 (50.3%) had neither CRF nor ESRD at the last follow-up. Female patients, compared with male patients, had a later mean age of onset of ESRD (76.0 [95% CI, 73.8 to 78.1] versus 68.1 [95% CI, 66.0 to 70.2] yr) and CRF (72.5 [95% CI, 70.1 to 74.9] versus 63.7 [95% CI, 61.4 to 66.0] yr). Linear regression and renal survival analyses revealed that the location of PKD2 mutations did not influence the age of onset of ESRD. However, patients with splice site mutations appeared to have milder renal disease compared with patients with other mutation types (P < 0.04 by log rank test; adjusted for the gender effect). Considerable renal disease variability was also found among affected individuals with the same PKD2 mutations. This variability can confound the determination of allelic effects and supports the notion that additional genetic and/or environmental factors may modulate the renal disease severity in ADPKD. E-mail: york.pei@uhn.on.ca 
500 uM (or 5.7 mg/dl) or the requirement of renal replacement therapy (chronic dialysis or renal transplantation). Chronic renal failure (CRF) is defined as moderately severe chronic renal failure with a calculated creatinine clearance 
A) was responsible for the mutation in three Spanish and two Canadian families. The frequencies of various clinical events (i.e., ESRD, CRF, and death) in the patients with different types of PKD2 mutations are detailed in Table 2. 
2 = 27.9; P < 0.00005 by log-rank test). On average, female patients developed ESRD 8 yr later than male patients with PKD2 mutations.
