New mutations in the PKD1 gene in Czech population with autosomal dominant polycystic kidney disease

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.     

Genetic heterogeneity of autosomal dominant polycystic kidney disease in Argentina.

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder with genetic heterogeneity. Up to three loci are involved in this disease, PKD1 on chromosome 16p13.3, PKD2 on 4q21, and a third locus of unknown location. Here we report the existence of locus heterogeneity for this disease in the Argentinian population by performing linkage analysis on 12 families of Caucasian origin. Eleven families showed linkage to PKD 1 and one family showed linkage to PKD2. Two recombinants in the latter family placed the locus PKD2 proximal to D4S1563, in agreement with data recently published on the cloning of this gene. Analysis of clinical data suggests a milder ADPKD phenotype for the PKD2 family.     

Genotypes of autosomal dominant polycystic kidney disease in Japanese

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary disorders. The prevalence of the ADPKD genotype in the Caucasian and Latin populations has been reported. Here, we used linkage analysis to demonstrate the prevalence of the genotype and the correlation between phenotypes and genotypes among 21 Japanese ADPKD families consisting of 96 individuals and including 57 affected members. Six polymorphic markers, each linked to either the polycystic kidney disease 1 (PKD1) or polycystic kidney disease 2 (PKD2) gene, were used for polymerase chain reaction analysis. Seventeen families (81%) showed linkage to PKD1, two families (10%) showed linkage to PKD2, and two families did not show linkage to either PKD1 or PKD2. One of the PKD1-linked families was indicated to have different mutations of PKD1 gene in the same family. PKD2-linked families did not have milder symptoms than PKD1-linked families. Received: October 9, 2001 / Accepted: November 9, 2001     

一个可能与PKD2基因连锁的常染色体显性多囊肾病家系

目的 研究常染色体显性多囊肾病（autosomal dominant polycystic kidney disease,ADPKD）在中国人中的遗传异质性。方法 采用聚合酶链反应 （polymerase chain reaction, PCR）、非变性聚丙烯酰胺凝胶电泳,检测了1个ADPKD家系各成员中与PKD1基因连锁的4种和与PKD2连锁的4种微卫星标记的基因分型。然后以软件辅助构建单倍型,并推测疾病单倍型。结果 发现该ADPKD家系中,与PKD1紧密连锁的4个微卫星KG8、SM6、CW4和CW2是有信息的;与PKD2基因紧密连锁的3种微卫星DNAIMS1563、D4S414和D4S423是有信息的。推定的单倍型提示,在这个家系中疾病可能与PKD2连锁,而不与PKD1连锁。结论 在此家系中,受累成员间存在表型异质性,并且有一个早发的儿童患者。与PKD2连锁的家系较少,这个家系的报道表明中国人中存在ADPKD的遗传异质性,PKD2的异常也可能会引起中国人ADPKD的发生。另外,发现有遗传早现现象存在,且疾病通过母亲传递。这提示在与PKD1不连锁的家系中后代可能早发病。     

DNA microsatellite analysis of families with autosomal dominant polycystic kidney disease types 1 and 2: evaluation of clinical heterogeneity between both forms of the disease.

We studied 17 large families affected by adult dominant polycystic kidney disease (ADPKD). Ultrasonographic analysis was performed on all the family members. DNA microsatellite markers closely linked to PKD1 on 16p13.3 were analysed, and linkage of the disease to this locus was determined. Families showing a negative linkage value were evaluated for linkage to the PKD2 locus on 4q. Five of the 17 families showed negative linkage for the 16p13.3 markers. In these families significant linkage to 4q was obtained. Renal cysts developed at an earlier age in PKD1 mutation carriers, and end stage renal failure occurred at an older age in people affected with PKD2. Analysis of large families with ADPKD in a Spanish population indicates that this is a genetically heterogeneous disorder, but mutations at only two loci are responsible for the development of the disease in most if not all the families. Clinicopathological differences between both forms of the disease occur, with subjects with ADPKD2 having a better prognosis than those with mutations at PKD1.     

Estimating locus heterogeneity in autosomal dominant polycystic kidney disease (ADPKD) in the Spanish population.

Although most mutations causing ADPKD in European populations have been mapped to the PKD1 locus on chromosome 16, some of them appear to be unlinked to this locus. To evaluate the incidence of unlinked mutations in Spain we have typed 31 Spanish families from different geographical sites for six closely linked DNA polymorphic marker loci flanking PKD1 detected by probes D16S85, D16S21, D16S259, D16S125, D16S246, and D16S80. Multilocus linkage analysis indicated that in 26 families the disease resulted from PKD1 mutations, whereas in three families it resulted from mutations in a locus other than PKD1. The two other families were not informative. Using the HOMOG test, the incidence of the PKD1 linked mutations in Spain is 85%. Multipoint linkage analysis in the 26 PKD1 families showed that the disease locus lies in the interval between D16S259(pGGG1) and D16S125(26.6).     

Autosomal dominant polycystic kidney disease: New information for genetic counselling

We evaluated the accuracy of ultrasonographic diagnosis of autosomal dominant polycystic kidney disease (ADPKD) and factors influencing its prognosis in members of 17 Newfoundland families originally described in 1984. In 10 families showing genetic linkage between ADPKD and markers for the PKD1 locus, rates of false negative ultrasonographic diagnosis are estimated as 36% below the age of 10 years and 8% or less thereafter, comparable with findings of genetic linkage studies of a subset of family members. At ages above 30 years, false negative ultrasonographic diagnosis of PKD1 disease is unlikely. In 2 families in which PKD1 disease is unlikely. In 2 families in which ADPKD is not coinherited with PKD1 markers, only 11% of members aged less than 30 years had kidney cysts. The mean (SE) age of onset of ESRD is 56.3 (1.8) years for persons with the PKD1 form of ADPKD, and 68.7 (1.7) years for affected members of families in which ADPKD is not co-inherited with PKD1 markers (P = 0.01). In the PKD1 families, age of onset of end stage renal disease (ESRD) was unrelated to the sex of the affected individual but was earlier in persons inheriting the disease from their mothers than from their fathers (50.5 vs. 64.8 years, P = 0.004), consistent with an influence of genetic imprinting on disease progresion. In females with a PKD1 mutation, onset of ESRD was not influenced by parity. In PKD1 families, resemblance in age of onset of ESRD was apparent; variation was less within than between families (F = 13.0, P < 0.0001), and risk of false negative ultrasonographic diagnosis appears largely restricted to families in which ESRD occurs relatively late. © 1992 Wiley-Liss, Inc.     

PKD2 gene mutation analysis in Korean autosomal dominant polycystic kidney disease patients using two-dimensional gene scanning

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous and is caused by mutations in the PKD1 or PKD2 genes. ADPKD caused by PKD2 mutations is characterized by a longer survival and a later onset of end-stage renal disease than ADPKD caused by PKD1 mutations. PKD2 encodes a 2.9-kb messenger RNA and is derived from 15 exons. Two-dimensional gene scanning (TDGS) is more efficient in detecting mutations in genes such as PKD2 because it can scan the whole coding regions simultaneously. In order to determine the prevalence of Korean PKD2 patients, all the coding sequences of PKD2 were screened using TDGS and direct sequencing in 46 randomly selected ADPKD patients (group 1). Another 45 ADPKD patients (group 2), who were presumed to be PKD2 patients, were screened in order to identify the type of mutation in the Korean PKD2 patients. Eight novel different mutations and three known mutations in the PKD2 gene were detected in 17 patients: 6 patients (13.0%) in group 1 and 11 patients (24.4%) in group 2. Considering the sensitivity of TDGS, the prevalence of PKD2 in Korean population might be greater than 18.6%. Both known and novel mutations were identified by TDGS in Korean PKD2 patients. Overall, these results showed that TDGS might be useful for diagnosing PKD2.     

Autosomal dominant polycystic kidney disease: new information for genetic counselling.

We evaluated the accuracy of ultrasonographic diagnosis of autosomal dominant polycystic kidney disease (ADPKD) and factors influencing its prognosis in members of 17 Newfoundland families originally described in 1984. In 10 families showing genetic linkage between ADPKD and markers for the PKD1 locus, rates of false negative ultrasonographic diagnosis are estimated as 36% below the age of 10 years and 8% or less thereafter, comparable with findings of genetic linkage studies of a subset of family members. At ages above 30 years, false negative ultrasonographic diagnosis of PKD1 disease is unlikely. In 2 families in which ADPKD is not co-inherited with PKD1 markers, only 11% of members aged less than 30 years had kidney cysts. The mean (SE) age of onset of ESRD is 56.3 (1.8) years for persons with the PKD1 form of ADPKD, and 68.7 (1.7) years for affected members of families in which ADPKD is not co-inherited with PKD1 markers (P = 0.01). In the PKD1 families, age of onset of end stage renal disease (ESRD) was unrelated to the sex of the affected individual but was earlier in persons inheriting the disease from their mothers than from their fathers (50.5 vs. 64.8 years, P = 0.004), consistent with an influence of genetic imprinting on disease progression. In females with a PKD1 mutation, onset of ESRD was not influenced by parity. In PKD1 families, resemblance in age of onset of ESRD was apparent; variation was less within than between families (F = 13.0, P less than 0.0001), and risk of false negative ultrasonographic diagnosis appears largely restricted to families in which ESRD occurs relatively late.     

Multipoint mapping of adult onset polycystic kidney disease (PKD1) on chromosome 16.

Analysis of genetic linkage data in 33 adult onset polycystic kidney (ADPKD) families was carried out using probes for the D16S85, D16S84, and D16S94 loci. The data set of 33 families shows no evidence of genetic heterogeneity since one unlinked family was previously excluded. Two point linkage analysis showed maximum likelihood values of the recombination fraction of 0.07 for ADPKD and D16S85 (lod score 18.78), 0.02 for ADPKD and D16S84 (lod score 7.55), and 0.00 for ADPKD and D16S94 (lod score 6.73). Multipoint analysis showed a maximum likelihood order of tel-D16S85-0.06-D16S84-0.02-(PKD1, D16S94)-cen with a multipoint lod score of 32.16. Analysis of rare recombinants lying close to PKD1 gave results consistent with this order.     

A family with a milder form of adult dominant polycystic kidney disease not linked to the PKD1 (16p) or PKD2 (4q) genes.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous disease. Most families show positive linkage to polymorphic markers around the PKD1 (16p13.3) or PKD2 (4q21-23) loci. The PKD1 and PKD2 genes have been cloned and mutations defined in a number of patients. Several clinical studies have described a milder phenotype for PKD2 patients. More recently, evidence for a third genetic locus has been found in one Portuguese, one French-Canadian, and one Italian family. We identified a Spanish family with negative linkage to the PKD1 and the PKD2 loci. This family showed a very mild clinical phenotype compared to the other forms of ADPKD, including the non-PKD1/non-PKD2 families previously described.     

Three novel mutations of the PKD1 gene in Korean patients with autosomal dominant polycystic kidney disease

Mutations at the PKD1 locus account for 85% of cases of the common genetic disorder called autosomal dominant polycystic kidney disease (ADPKD). Screening for mutations of the PKD1 gene is complicated by the genomic structure of the 5'-duplicated region encoding 75% of the gene. To date, more than 90 mutations of the PKD1 gene have been reported in the European and American populations, and relatively little information is available concerning the pattern of mutations present in the Asian populations. We looked for mutations of the PKD1 gene in 51 unrelated Korean ADPKD patients, using polymerase chain reaction (PCR) with primer pairs located in the 3' single-copy region of the PKD1 gene and by single-strand conformation polymorphism (SSCP) analysis. We found three novel mutations, a G to A substitution at nucleotide 11012 (G3601S), a C to A substitution at nucleotide 11312 (Q3701X), and a C to T substitution at nucleotide 12971 (P4254S), and a single polymorphism involving a G to C substitution at nucleotide 11470 (L3753L). These mutations were not found in control individuals, and no other mutations in the 3' single-copy region of the PKD1 gene of patients with these mutations were observed. In particular, P4254S segregated with the disease phenotype. The clinical data of affected individuals from this study, and of previously reported Korean PKD1 mutations, showed that patients with frameshift or nonsense mutations were more prone to develop end-stage renal failure than those with missense mutations. Our findings indicate that many different PKD1 mutations are likely to be responsible for ADPKD in the Korean population, as in the Western population.     

Genes homologous to the autosomal dominant polycystic kidney disease genes (PKD1 and PKD2)

Autosomal Dominant Polycystic Kidney Disease (ADPKD), a common inherited disease leading to progressive renal failure, can be caused by a mutation in either the PKD1 or PKD2 gene. Both genes encode for putative transmembrane proteins, polycystin-1 and polycystin-2, which show significant homology to each other and are believed to interact at their carboxy termini. To identify genes that code for related proteins we searched for homologous sequences in several databases and identified one partial cDNA and two genomic sequences with significant homology to both polycystin-1 and - 2. Further analysis revealed one novel gene, PKD2L2, located on chromosome band 5q31, and two recently described genes, PKD2L and PKDREJ, located on chromosome bands 10q31 and 22q13.3, respectively. PKD2L2 and PKD2L, which encode proteins of 613 and 805 amino acids, are approximately 65% similar to polycystin-2. The third gene, PKDREJ, encodes a putative 2253 amino acid protein and shows about 35% similarity to both polycystin-1 and polycystin-2. For all the genes expression was found in testis. Additional expression of PKD2L was observed in retina, brain, liver and spleen by RT-PCR. Analyses of five ADPKD families without clear linkage to either the PKD1 or PKD2 locus showed no linkage to any of the novel loci, excluding these genes as the cause of ADPKD in these families. Although these genes may not be involved in renal cystic diseases, their striking homology to PKD2 and PKD1 implies similar roles and may contribute to elucidating the function of both polycystin-1 and polycystin-2.     

Matching clinical and genetic diagnoses in autosomal dominant polycystic kidney disease reveals novel phenocopies and potential candidate genes

PurposeAutosomal dominant polycystic kidney disease (ADPKD) represents the most common hereditary nephropathy. Despite growing evidence for genetic heterogeneity, ADPKD diagnosis is still primarily based upon clinical imaging criteria established before discovery of additional PKD genes. This study aimed at assessing the diagnostic value of genetic verification in clinical ADPKD.MethodsIn this prospective, diagnostic trial, 100 families with clinically diagnosed ADPKD were analyzed by PKD gene panel and multiplex ligation-dependent probe amplification (MLPA); exome sequencing (ES) was performed in panel/MLPA-negative families.ResultsDiagnostic PKD1/2 variants were identified in 81 families (81%), 70 of which in PKD1 and 11 in PKD2. PKD1 variants of unknown significance were detected in another 9 families (9%). Renal survival was significantly worse upon PKD1 truncation versus nontruncation and PKD2 alteration. Ten percent of the cohort were PKD1/2-negative, revealing alternative genetic diagnoses such as autosomal recessive PKD, Birt–Hogg–Dubé syndrome, and ALG9-associated PKD. In addition, among unsolved cases, ES yielded potential novel PKD candidates.ConclusionBy illustrating vast genetic heterogeneity, this study demonstrates the value of genetic testing in a real-world PKD cohort by diagnostic verification, falsification, and disease prediction. In the era of specific treatment for fast progressive ADPKD, genetic confirmation should form the basis of personalized patient care.     

A comprehensive search for mutations in the PKD1 and PKD2 in Japanese subjects with autosomal dominant polycystic kidney disease

To elucidate the genotypic and phenotypic characteristics of autosomal dominant polycystic kidney disease (ADPKD) in Japanese populations, we performed a comprehensive search for mutations in PKD1 and PKD2 in 180 Japanese ADPKD patients from 161 unrelated families. We identified 112 (89 PKD1 and 23 PKD2) mutations within 135 families. Patients with PKD2 mutations account for 23.6% of all Japanese ADPKD families in this study. Seventy‐five out of the 112 mutations have not been reported previously. The estimated glomerular filtration rate (eGFR) decline was significantly faster in patients with PKD1 mutations than in those with PKD2 mutations (?3.25 and ?2.08 ml min^?1 year^?1 for PKD1 and PKD2, respectively, p < 0.01). These results indicate that mutations within PKD1 and PKD2 can be linked to most of the cases of Japanese ADPKD, and the renal function decline was faster in patients with PKD1 mutations than in those with PKD2 mutations also in the Japanese ADPKD. We also found that PKD2 mutations were more frequent in Japanese ADPKD than that in European or American ADPKD.     

Mutational analysis of PKD1 gene in a Chinese family with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary disease and common renal disease. Mutations of PKD genes are responsible for this disease. We analyzed a large Chinese family with ADPKD using Sanger sequencing to identify the mutation responsible for this disease. The family comprised 27 individuals including 10 ADPKD patients. These ADPKD patients had severe renal disease and most of them died very young. We analyzed 6 survival patients gene and found they all had C10529T mutation in exon 35 of PKD1 gene. We did not found gene mutation in any unaffected relatives or 300 unrelated controls. These findings suggested that the C10529T mutation in PKD1 gene might be the pathogenic mutation responsible for the disease in this family.     

Kidney enlargement and multiple liver cyst formation implicate mutations in PKD1/2 in adult sporadic polycystic kidney disease

Distinguishing autosomal‐dominant polycystic kidney disease (ADPKD) from other inherited renal cystic diseases in patients with adult polycystic kidney disease and no family history is critical for correct treatment and appropriate genetic counseling. However, for patients with no family history, there are no definitive imaging findings that provide an unequivocal ADPKD diagnosis. We analyzed 53 adult polycystic kidney disease patients with no family history. Comprehensive genetic testing was performed using capture‐based next‐generation sequencing for 69 genes currently known to cause hereditary renal cystic diseases including ADPKD. Through our analysis, 32 patients had PKD1 or PKD2 mutations. Additionally, 3 patients with disease‐causing mutations in NPHP4, PKHD1, and OFD1 were diagnosed with an inherited renal cystic disease other than ADPKD. In patients with PKD1 or PKD2 mutations, the prevalence of polycystic liver disease, defined as more than 20 liver cysts, was significantly higher (71.9% vs 33.3%, P = .006), total kidney volume was significantly increased (median, 1580.7 mL vs 791.0 mL, P = .027) and mean arterial pressure was significantly higher (median, 98 mm Hg vs 91 mm Hg, P = .012). The genetic screening approach and clinical features described here are potentially beneficial for optimal management of adult sporadic polycystic kidney disease patients.     

PGD for autosomal dominant polycystic kidney disease type 1

Autosomal dominant polycystic kidney disease (ADPKD) is primarily characterized by renal cysts and progression to renal failure. It is a genetically heterogeneous disease, with mutations in the PKD1 gene accounting for the majority of cases. Direct mutation detection for PKD1-linked ADPKD or type 1 is complicated by the large size and complex genomic structure of PKD1. This paper describes a microsatellite marker-based assay for PGD in couples at risk of transmitting ADPKD type 1. During PGD, genetic analysis is carried out on single blastomeres biopsied from preimplantation embryos obtained after IVF, and only embryos unaffected by the disease under investigation are selected for transfer. Single-cell genetic analysis relied on a fluorescent duplex-PCR of linked polymorphic markers followed by fragment length determination on an automated sequencer. The co-amplification of the intragenic KG8 and the extragenic D16S291 marker at the single-cell level was evaluated in pre-clinical tests on lymphoblasts and research blastomeres. The developed assay proved to be efficient (96.1% amplification) and accurate (1.4% allele drop-out and 4.3% contamination), and can be applied in all informative ADPKD type 1 couples. From five clinical cycles carried out for three couples, two pregnancies ensued, resulting in the birth of two healthy children.     

Presymptomatic molecular diagnosis of autosomal dominant polycystic kidney disease using PKD1-and PKD2-linked markers in Cypriot families

Autosomal dominant polycystic kidney disease (ADPKD), is a heterogeneous disorder, primarily characterized by the formation of cysts in the kidneys, and the late development in life of progressive chronic kidney failure. Three genes are implicated in causing ADPKD. One on chromosome 16, PKD1, accounts for 85–90% of all cases, and the PKD2 gene on chromosome 4 accounts for the remainder. A very rare third locus is still of unknown location. We used PKD1-and PKD2-linked polymorphic markers to make the diagnosis of ADPKD in young presymptomatic members in affected families. We showed that in young members of families where clinical diagnosis cannot be definitively established, molecular linkage analysis can assist clinicians in the diagnosis. In one family a 24-year old had one cyst on the right kidney; however, molecular analysis showed clearly that he had inherited the normal haplotype. In another family, in one part of the pedigree there was co-inheritance of the disease with a PKD1-linked haplotype which originated in a non-affected 78-year-old father. Analysis with PKD2-linked markers excluded this locus. The data can be explained in one of two ways. Either this family phenotype is linked to a third locus, or the proband was the first affected person, most probably because of a novel mutation in one of her father's chromosomes. In conclusion, the combined use of markers around the PKD1 and the PKD2 locus provides more definitive answers in cases where presymptomatic diagnosis is requested by concerned families.     

Four novel mutations of the PKD2 gene in Czech families with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous disease caused by mutations in at least three different loci. Mutations in the PKD2 gene are responsible for approximately 15% of the cases of the disease. We have screened 14 Czech families for mutation in the PKD2 gene. Clear evidence against linkage to the PKD1 gene was established by CA-repeat markers in five families. The disease could be linked to both genes according to linkage analysis in nine families but we have chosen these families because of the mild clinical course. An affected member from each family was analyzed by heteroduplex analysis (HA) and single strand conformation polymorphism (SSCP) for all 15 coding regions. Samples exhibiting shifted bands on HA or SSCP gels were sequenced. We detected five mutations (four new, and one which was previously described) and two polymorphisms. The four new mutations include one insertion, one deletion, one substitution (leading to premature translation stop), one amino acid substitution. Our results confirm that different point or small changes distributed throughout the PKD2 gene without clustering are responsible for the disease.