The correlation between kidney volume and measured glomerular filtration rate in an Asian ADPKD population: a prospective cohort study.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disorder that leads to end stage renal disease (ESRD). Cyst expansion in ADPKD is strongly associated with the decline in renal function. However, the correlation between total kidney volume (TKV) and glomerular filtration rate (GFR) at an early stage has not been well demonstrated. There is growing evidence that utilization of estimated GFR (eGFR) may induce misleading information in a population with near normal renal function. Therefore, a more accurate method is essential. METHODS: A prospective cohort of ADPKD patients was conducted with clinical data and laboratory collection. Measured GFR (mGFR) was assessed by iohexol plasma clearance method using ultra performance liquid chromatography. eGFR was calculated using the CKD-EPI equation. Kidney volumes were evaluated using MRI imaging protocol. RESULTS: Thirty two patients completed the study. The mean age was 56 years old. The mean initial mGFR was 83.8 mL/min/1.73m2. The mean change in mGFR per year was -2.99 mL/min/1.73m2/year. The mean initial height-adjusted TKV (htTKV) was 681.0 mL/m. The mean percentage change in htTKV per year (%ΔhtTKV/y) was 4.77 %/year. mGFR had a better association with clinical parameters than eGFR. Initial mGFR was significantly and inversely correlated with initial htTKV and age. The percentage change in mGFR per year was significantly and inversely correlated with the %ΔhtTKV/y and 24-hr urine albumin. The %ΔhtTKV/y was significantly correlated with initial htTKV. CONCLUSIONS: Our studies demonstrated that mGFR using iohexol is a more reliable and accurate method than eGFR for evaluating GFR changes in the early stages of ADPKD patients. There is a strong inverse correlation between kidney volume and mGFR in an Asian ADPKD population. The initial htTKV is a good predictor of kidney volume progression. The %ΔhtTKV/y is a good early surrogate marker for the decline in renal function. 24-hr urine albumin is also a good indicator for renal progression.

Mutation analyses by next-generation sequencing and multiplex ligation-dependent probe amplification in Japanese autosomal dominant polycystic kidney disease patients.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD), one of the most common hereditary kidney diseases, causes gradual growth of cysts in the kidneys, leading to renal failure. Owing to the advanced technology of next-generation sequencing (NGS), genetic analyses of the causative genes PKD1 and PKD2 have been improved. METHODS: We performed genetic analyses of 111 Japanese ADPKD patients using hybridization-based NGS and long-range (LR)-PCR-based NGS. Additionally, genetic analyses in exon 1 of PKD1 using Sanger sequencing because of an extremely low coverage of NGS and those using multiplex ligation-dependent probe amplification (MLPA) were performed. RESULTS: The detection rate using NGS for 111 patients was 86.5%. One mutation in exon 1 of PKD1 and five deletions detected by MLPA were identified. When combined, the total detection rate was 91.9%. CONCLUSION: Although NGS is useful, we propose the addition of Sanger sequencing for exon 1 of PKD1 and MLPA as indispensable for identifying mutations not detected by NGS.

Revisiting racial differences in ESRD due to ADPKD in the United States.

INTRODUCTION: Autosomal dominant polycystic kidney disease (ADPKD) affects all races. Whether the progression of ADPKD varies by race remains unclear. METHODS: In this retrospective cohort study from 2004 to 2013 non-Hispanic blacks and non-Hispanic whites of all ages classified in the US Renal Data System (USRDS) with incident ESRD from ADPKD (n = 23,647), hypertension/large vessel disease (n = 296,352), or diabetes mellitus (n = 451,760) were stratified into five-year age categories ranging from < 40 to > 75 (e.g., < 40, 40-44, 45-49, …, 75+). The Cochran-Mantel-Haenszel test was used to determine the association of race and incidence of ESRD from ADPKD, diabetes, or hypertension. The difference in the proportions of ESRD in non-Hispanic black and non-Hispanic white patients at each age categorical bin was compared by two-sample proportion test. The age of ESRD onset between non-Hispanic black and non-Hispanic white patients at each year was compared using two-sample t-test with unequal variance. RESULTS: 1.068% of non-Hispanic blacks and 2.778% of non-Hispanic whites had ESRD attributed to ADPKD. Non-Hispanic blacks were less likely than non-Hispanic whites to have ESRD attributed to ADPKD (odds ratio (OR) (95% CI) = 0.38 (0.36-0.39), p <  0.0001). Using US Census data as the denominator to adjust for population differences non-Hispanic blacks were still slightly under-represented (OR (95% CI) 0.94 (0.91-0.96), p = 0.004). However, non-Hispanic blacks with ADPKD had a younger age of ESRD (54.4 years ±13) than non-Hispanic whites (55.9 years ±12.8) (p <  0.0001). For those < 40 years old, more non-Hispanic blacks had incident ESRD from ADPKD than non-Hispanic whites (9.49% vs. 7.68%, difference (95% CI) = 1.81% (0.87-2.84%), p <  0.001) for the combined years examined. CONCLUSIONS: As previously shown, we find the incidence of ESRD from ADPKD in non-Hispanic blacks is lower than in non-Hispanic whites. Among the younger ADPKD population (age < 40), however, more non-Hispanic blacks initiated dialysis than non-Hispanic whites. Non-Hispanic blacks with ADPKD initiated dialysis younger than non-Hispanic whites. A potential implication of these findings may be that black race should be considered an additional risk factor for progression in ADPKD.

Identification of novel mutations and risk assessment of Han Chinese patients with autosomal dominant polycystic kidney disease.

AIM: Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease in humans and is caused by mutations in the PKD1 or PKD2 gene. ADPKD is heterogeneous with regard to locus and allele heterogeneity and phenotypic variability. METHODS: Using targeted capture associated with next generation sequencing (NGS), we performed a mutational analysis of Han Chinese patients with ADPKD from 62 unrelated families. Multivariate Cox proportional hazard modelling of their different clinical characteristics and mutation classes was performed. RESULTS: The detection rate for a PKD1 and PKD2 mutation in the Chinese ADPKD patients was 95.2% (59/62). We identified pathogenic mutations in 64.4% (38/59) of patients, including 32PKD1 mutations (15 nonsense mutations, 15 frameshift mutation, one splice mutation, and one large deletion) and six PKD2 mutations (three nonsense mutations and three frameshift mutations). Of the pathogenic variants we identified, 50% (19/38) were novel variants and 50% (19/38) were known variants. Patients with PKD2 mutations had milder and indistinguishable phenotypes. Significant phenotypic differences were observed among the various types of PKD1 mutations. CONCLUSION: Our results show that targeted capture associated with next-generation sequencing is an effective strategy for genetically testing ADPKD patients. This mutation analysis of ADPKD in Han Chinese extends our understanding of the genetic diversity of different ethnic groups, enriches the mutation database, and contributes to the genetic counselling of ADPKD patients.

Baseline characteristics of the autosomal-dominant polycystic kidney disease sub-cohort of the KoreaN cohort study for outcomes in patients with chronic kidney disease.

AIM: The aim of this study was to describe the baseline characteristics of autosomal-dominant polycystic kidney disease (ADPKD) in a cohort of Korean patients with chronic kidney disease (CKD). METHODS: From April 2011 to February 2016, patients with CKD stage 1-5 (pre-dialysis) were enrolled as an ADPKD sub-cohort of the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease. Baseline characteristics, the correlation of kidney and liver volume and kidney function and the factors associated with kidney function were analysed. RESULTS: A total of 364 ADPKD patients with a mean estimated glomerular filtration rate (eGFR) of 68.1 ± 33.3 mL/min per 1.73 m2 (50.5% male with a mean age of 47.0 ± 10.6 years) were enrolled from nine hospitals in Korea. Initially, 55.8% of the patients were asymptomatic, and pain was the most common symptom (12.9%); 87.6 and 77.5% of the patients had hypertension and hepatic cysts, respectively. The height-adjusted total kidney volumes (htTKV) were higher in male patients than in female patients. In contrast, the height-adjusted total liver volumes were higher in female patients than in male patients. The decrease rate of eGFR depending on Log(htTKV) was larger in the group aged between 41 and 50 years than the other age groups. Older age, a higher 24-h urine protein excretion, larger htTKV and hyperuricemia were independently associated with lower eGFR, whereas using febuxostat was independently associated with higher eGFR. CONCLUSION: This sub-cohort will provide clinical characteristics and outcomes of Korean ADPKD patients, which can be compared with those of other previous cohorts. We have identified factors associated with advanced-stage CKD in Korean patients with ADPKD.

A novel splicing mutation in the PKD1 gene causes autosomal dominant polycystic kidney disease in a Chinese family: a case report.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic renal disorder in humans, affecting 1 in 400 to 1000 individuals. Mutations PKD1 (which accounts for 85% of ADPKD and produces polycystin-1) and PKD2 (produces polycystin-2) are responsible for this disease. These two polycystins are critical for maintaining normal renal tubular structures during kidney development. CASE PRESENTATION: We performed genetic analysis on a family with ADPKD. DNA samples extracted from ADPKD patient blood were subject to targeted Next generation sequencing for human a panel of renal disease-related genes. A splicing mutation, c.2854-3C > G (also known as IVS11-3C > G), in the PKD1 gene was found in the 3 patients from the family, but was not found in four unaffected relatives and 100 normal control samples. Reverse transcription-PCR (RT-PCR) was performed to analyse the relative mRNA expression in the patient samples. mRNA sequencing showed that 29 bases inserted into the 3'-end of exon 11 in the PKD1 gene lead to a frameshift mutation. CONCLUSIONS: The PKD1 c.2854-3C > G mutation leads to a frameshift mutation during translation of the polycystin-1 protein, which eventually led to ADPKD in the Chinese family.

Novel mutations of PKD genes in Chinese patients suffering from autosomal dominant polycystic kidney disease and seeking assisted reproduction.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD), the commonest inherited kidney disease, is generally caused by heterozygous mutations in PKD1, PKD2, or GANAB (PKD3). METHODS: We performed mutational analyses of PKD genes to identify causative mutations. A set of 90 unrelated families with ADPKD were subjected to mutational analyses of PKD genes. Genes were analysed using long-range PCR (LR-PCR), direct PCR sequencing, followed by multiplex ligation-dependent probe amplification (MLPA) or screening of GANAB for some patients. Semen quality was assessed for 46 male patients, and the correlation between mutations and male infertility was analysed. RESULTS: A total of 76 mutations, including 38 novel mutations, were identified in 77 families, comprising 72 mutations in PKD1 and 4 in PKD2, with a positive detection rate of 85.6%. No pathogenic mutations of GANAB were detected. Thirty-seven patients had low semen quality and were likely to be infertile. No association was detected between PKD1 mutation type and semen quality. However, male patients carrying a pathogenic mutation in the Ig-like repeat domain of PKD1 had a high risk of infertility. CONCLUSION: Our study identified a group of novel mutations in PKD genes, which enrich the PKD mutation spectrum and might help clinicians to make precise diagnoses, thereby allowing better family planning and genetic counselling. Men with ADPKD accompanied by infertility should consider intracytoplasmic sperm injection combined with preimplantation genetic diagnosis to achieve paternity and obtain healthy progeny.

Real-world costs of autosomal dominant polycystic kidney disease in the Nordics.

BACKGROUND: There is limited real-world data on the economic burden of patients with autosomal dominant polycystic kidney disease (ADPKD). The objective of this study was to estimate the annual direct and indirect costs of patients with ADPKD by severity of the disease: chronic kidney disease (CKD) stages 1-3; CKD stages 4-5; transplant recipients; and maintenance dialysis patients. METHODS: A retrospective study of ADPKD patients was undertaken April-December 2014 in Denmark, Finland, Norway and Sweden. Data on medical resource utilisation were extracted from medical charts and patients were asked to complete a self-administered questionnaire. RESULTS: A total of 266 patients were contacted, 243 (91%) of whom provided consent to participate in the study. Results showed that the economic burden of ADPKD was substantial at all levels of the disease. Lost wages due to reduced productivity were large in absolute terms across all disease strata. Mean total annual costs were highest in dialysis patients, driven by maintenance dialysis care, while the use of immunosuppressants was the main cost component for transplant care. Costs were twice as high in patients with CKD stages 4-5 compared to CKD stages 1-3. CONCLUSIONS: Costs associated with ADPKD are significant and the progression of the disease is associated with an increased frequency and intensity of medical resource utilisation. Interventions that can slow the progression of the disease have the potential to lead to substantial reductions in costs for the treatment of ADPKD.

Identification of novel PKD1 and PKD2 mutations in Korean patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder. It is caused by mutations in the PKD1 and PKD2 genes, and manifests as progressive cyst growth and renal enlargement, resulting in renal failure. Although there have been a few studies on the frequency and spectrum of mutations in PKD1 and PKD2 in Korean patients with ADPKD, only exons 36-46, excluding the duplicated region, were analyzed, which makes it difficult to determine accurate mutation frequencies and mutation spectra. METHODS: We performed sequence analysis of 20 consecutive unrelated ADPKD patients using long-range polymerase chain reaction (PCR) to avoid pseudogene amplification, followed by exon-specific PCR and sequencing of the all exons of these two genes. Multiplex ligation-dependent probe amplification was performed in patients in whom pathogenic mutations in PKD1 or PKD2 were not identified by LR-PCR and direct sequencing to detect large genomic rearrangements. RESULTS: All patients met the diagnostic criteria of ADPKD, and pathogenic mutations were found in 18 patients (90.0%), comprising 15 mutations in PKD1 and three in PKD2. Among 10 novel mutations, eight mutations were found in the PKD1 gene while two mutations were found in the PKD2 gene. Eight of 14 PKD1 mutations (57.1%) were located in the duplicated region. CONCLUSIONS: This study expands the spectra of mutations in the PKD1 and PKD2 genes and shows that the mutation frequencies of these genes in Korean ADPKD patients are similar to those reported in other ethnicities. Sequence analysis, including analysis of the duplicated region, is essential for molecular diagnosis of ADPKD.

Effects of endothelial nitric oxide synthase gene on end stage renal disease progression in autosomal dominant polycystic kidney disease.

AIM: To investigate whether endothelial nitric oxide synthase (eNOS) gene associate with the progression of autosomal dominant polycystic kidney disease (ADPKD). METHODS: Databases of EMBASE, Pubmed, ISI, Ovid Database, Cochrane library and China National Knowledge Infrastructure were all searched. Associated studies about eNOS polymorphisms and ADPKD were analyzed by meta-analysis. RESULTS: A total of 11 studies with Glu298Asp and 4b/a polymorphisms were included. A allele of the 4b/a polymorphism increased the risk of end stage renal disease (ESRD) in ADPKD (odds ratio (OR) = 1.85, 95% confidence interval (CI) 1.17-2.94, P = 0.009). However, GG phenotype of Glu298Asp polymorphism neither decreased the ESRD risk (OR = 0.77, 95% CI 0.55-1.08, P = 0.13) nor affected the hypertension risk (OR = 1.04, 95% CI 0.66-1.66, P = 0.86). The GG phenotype carriers had later ESRD age compared with the T allele of Glu298Asp polymorphism (WMD = 2.39; 95% CI 1.32-3.46; P < 0.0001). Significant association was also found in Caucasians (WMD = 2.41; 95% CI 1.18-3.64; P = 0.0001). Subgroup analysis by gender indicated GG genotype carriers had older age of ESRD than T allele carriers in males (WMD = 4.51; 95% CI 3.95-5.08; P = 0.00001), but not in females. CONCLUSIONS: GG genotype of the Glu298Asp variant slowed the ESRD progression in ADPKD, while a allele carriers of the 4b/a variant increased the risk of ESRD. Variants of eNOS gene might play different roles in the ESRD progression in ADPKD.

A new PKD1 mutation discovered in a Chinese family with autosomal polycystic kidney disease.

BACKGROUND/AIMS: Autosomal-dominant polycystic kidney disease (ADPKD), a heterogeneous genetic disorder characterized by massive kidney enlargement and progressive chronic kidney disease, is due to abnormal proliferation of renal tubular epithelium. ADPKD is known to be caused by mutations in PKD1 and PKD2 genes. METHODS: In the present study, the mutation analysis of PKD genes was performed in a new Chinese family with ADPKD using Long-Range (LR) PCR sequencing and targeted next-generation sequencing (targeted DNA-HiSeq). RESULTS: A unique 28 bp deletion (c.12605_12632del28) in exon 46 of the PKD1 gene was identified in two affected family members by LR PCR method, but not in any unaffected relatives or unrelated controls. Higher accuracy and less missing detection presented in LR PCR method compared with targeted DNA-HiSeq. This mutation c.12605_12632del28 (p.Arg4202ProextX146) resulted in a delayed termination of amino acid code, and was highly speculated pathogenic in this ADPKD family. Moreover, this newly identified frame-shift change was compared to the PKD gene database, but no similar mutation was yet reported. CONCLUSION: A novel frame-shift mutation, c. 12605_12632del28, in the PKD1 gene was found in a Chinese ADPKD family. All evidence available suggested that it might be the mutation responsible for the disease in that family.

Patterns of autosomal dominant polycystic kidney diseases in black Africans.

Autosomal dominant polycystic kidney disease (ADPKD) is not well described in black Africans while some data suggesting the disease is exceptional in this race. A retrospective study of patients with ADPKD followed in nephrology department of a teaching hospital in Dakar (January 1, 1995 to December 31, 2005) was therefore undertaken. Prevalence of ADPKD was one in 250. Mean age was 47 + or - 5 years with a predominance of male (57%). High blood pressure (HBP) was present in 68% of patients. Other renal manifestations were flank pain, hematuria and proteinuria. Majority of patients had impaired renal function at time of diagnosis. Extra-renal cysts were essentially found in liver (45.5%), pancreas and seminal vesicles. Main complications: ESRD (51%) occurred within a 6 year mean period, urinary tract infection (13%) and cerebral haemorrhage (2%). HBP control, in general needed 2 or more antihypertensive drugs. Fourteen patients died, ten patients had been on haemodialysis and four others died from uremic complications. In conclusion, ADPKD in black African adults is not rare and probably underdiagnosed. Early HBP and ESRD are likely more frequent than in other races. Earlier ultrasound detection and strategies to preserve renal function should be offered to at-risk individuals to improve outcomes.

DNA microsatellite analysis in families with autosomal dominant polycystic kidney disease (ADPKD): the first Polish study.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited renal disorders with genetic heterogeneity. Mutations of two known genes are responsible for this disease: PKD1 at 16p13.3 and PKD2 at 4q21-23. A majority of cases (85%) are caused by mutations in PKD1. Because direct mutation screening remains complex, we describe here the application of an efficient approach to studies based on highly informative dinucleotide and tetranucleotide repeats flanking genes PKD1 and PKD2. METHODS: For this study a series of microsatellites closely linked to locus PKD1 (D16S291, D16S663, D16S665, D16S283, D16S407, D16S475) and to locus PKD2 (D4S1563, D4S2929, D4S414, D4S1534, D4S423) were selected. Short (81-242 bp) DNA fragments containing the tandem repeats were amplified by polymerase chain reaction (PCR). The number of repeat units of microsatelite markers was determined by fluorescent capillary electrophoresis. RESULTS: DNA microsatellite analysis was performed in 25 Polish ADPKD families and established the type of disease (21 families PKD1-type, 1 family PKD2-type). CONCLUSIONS: While a disease-causing mutation in the PKD1 and PKD2 genes cannot be identified, DNA microsatellite analysis provided an early diagnosis and may be considered in ADPKD families.

[Mutation detection of ADPKD PKD1 gene in Hans by denaturing high-performance liquid chromatography].

OBJECTIVE: To develop a screening system for more rapid and sensitive mutation detection of autosomal dominant polycystic kidney disease (ADPKD) gene 1 (PKD1) by using denaturing high-performance liquid chromatography (DHPLC) protocol. METHODS: Using genomic DNA as templates extracted from blood samples of 19 Han pedigrees with 67 family members, the complete codon areas were amplified by long-range PCR and nested PCR in succession, and then the PCR products were analyzed by DHPLC. The mutations from screened abnormal PCR products were confirmed by DNA sequencing, and then compared with the mutations identified by single strand conformation polymorphism (SSCP) before. RESULTS: There were 14 mutations found in this study, including 10 missense, 1 insertion, 1 deletion and 2 nonsense mutations. Besides 12 mutations identified before, mutations nt32819G>A and nt37137T>C were the novel mutations found. The mutation detection ratio was 73.7%. CONCLUSION: This developed system via DHPLC can be used as a more effective approach for mutation detection of autosomal dominant polycystic kidney disease PKD1 in Hans.

PKD1 and PKD2 mutations in Slovenian families with autosomal dominant polycystic kidney disease.

BACKGROUND: Autosomal 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. METHODS: We 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 . RESULTS: Lod 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. CONCLUSION: In 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.

[A Chinese autosomal dominant polycystic kidney disease family probably related to PKD2 gene].

OBJECTIVE: To study the genetic heterogeneity of autosomal dominant polycystic kidney disease (ADPKD) in Chinese. METHODS: Using polymerase chain reaction (PCR) and non-denatured polyacrylamide gel electrophoresis, the authors analyzed eight microsatellite markers closely linked to PKD1 or PKD2 genes respectively in a Chinese ADPKD family. RESULTS: Seven informative markers were found in this family, including KG8, SM6, CW4 and CW2 which are tightly linked to PKD1, and D4S1563, D4S414 and D4S423 which are linked to PKD2. After the process of genotyping, the haplotypes were estimated with Cyrillic 2.0, and the linkage-based analysis suggested that the disease is not linked to PKD1 other than PKD2. CONCLUSION: In China this non-PKD1 family is the second one, but it is the first reported PKD2 family showing the genetic heterogeneity of ADPKD in Chinese. In the family the affected mother transmits the disease and the affected members' phenotypes are eterogeneous. In addition, the existing "anticipation" and the presence of the disease in a child of this family suggest that non-PKD1 linked families may have early-onset of the disease in child.

Mutation analysis of autosomal dominant polycystic kidney disease genes in Han Chinese.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in two genes, PKD1 and PKD2. The complexity of these genes, particularly PKD1, has complicated genetic screening, though recent advances have provided new opportunities for amplifying these genes. In the Han Chinese population, no complete mutational analysis has previously been conducted across the entire span of PKD1 and PKD2. Here, we used single-strand conformation polymorphism (SSCP) analysis to screen the entire coding sequence of PKD1 and PKD2 in 85 healthy controls and 72 Han Chinese from 24 ADPKD pedigrees. In addition to 11 normal variants, we identified 17 mutations (12 in PKD1 and 5 in PKD2), 15 of which were novel ones (11 for PKD1 and 4 for PKD2). We did not identify any seeming mutational hot spots in PKD1 and PKD2. Notably, we found several disease-associated C-T or G-A mutations that led to charge or hydrophobicity changes in the corresponding amino acids. This suggests that the mutations cause conformational alterations in the PKD1 and PKD2 protein products that may impact the normal protein functions. Our study is the first report of screenable mutations in the full-length PKD1 and PKD2 genes of the Han Chinese, and also offers a benchmark for comparisons between Caucasian and Han ADPKD pedigrees and patients.

Medullary cystic kidney disease type 1 in a large Native-American kindred.

BACKGROUND: Autosomal dominant medullary cystic kidney disease type 1 (MCKD1; Mendelian Inheritance in Man 174000) is a hereditary tubulointerstitial renal disease. For MCKD1, a locus on chromosome 1q21 is published. Although there are characteristic biopsy and imaging findings for MCKD, clinical diagnosis of this disorder is still very difficult because unique phenotypic features are not always present in individual cases. METHODS: In a large Native-American kindred with apparent autosomal dominant nephropathy, clinical findings in more than 50 individuals were collected and evaluated. Haplotype analysis for 34 individuals was performed. RESULTS: We report the difficulties establishing the diagnosis of MCKD in a large Native-American kindred solely by means of clinical criteria. This kindred shows a wider range of age of disease onset than previously reported. Gout and hypertension were common, but no patient reported symptoms of salt wasting. By means of haplotype analysis linkage was shown to the MCKD1 locus (logarithm of the odds score, 3.34). CONCLUSION: Establishing a diagnosis of MCKD solely on clinical findings is difficult because signs and symptoms may be subtle, renal cysts may be absent in more than 50% of affected individuals, and renal histological abnormalities are nonspecific. In patients presenting with renal insufficiency from apparent interstitial disease, a thorough family history and genetic linkage studies are required to establish a diagnosis of MCKD. We suspect MCKD is underdiagnosed and the true incidence of MCKD1 in the general population may be underestimated. No further living-related transplantation should be performed until genetic testing can exclude potentially affected donors.

Abnormal hepatocystin caused by truncating PRKCSH mutations leads to autosomal dominant polycystic liver disease.

Mutations in protein kinase C substrate 80K-H (PRKCSH), encoding for the protein hepatocystin, cause autosomal dominant polycystic liver disease (PCLD), which is clinically characterized by the presence of multiple liver cysts. PCLD has been documented in families from Europe (Netherlands, Belgium, Finland) as well as from the United States. In this article, we report results from extensive mutational analysis of the PRKCSH gene in a group of 14 PCLD families and 65 singleton cases of Dutch and Finnish descent with multiple simple liver cysts. We identified PRKCSH mutations in 12 families and in 3 sporadic cases. In 8 of 10 Finnish families we detected the 1437+2delTG splice-site mutation. In Dutch families, we found 2 other mutations that affect correct splicing of PRKCSH: 292+1 G>C (2 families) and 1338-2 A>G (1 family). In another Dutch family, we detected a novel deletion (374-375delAG) in exon 6, predicting an abnormal shortened protein. Investigation of the carrier haplotypes identified a common founder chromosome in unrelated individuals in each of the 3 identified splice-site mutations. In 2 Finnish families with dominantly inherited PCLD, and in 62 of 65 sporadic cases with multiple simple liver cysts, we failed to demonstrate any PRKCSH mutation. This corroborates the notion that autosomal dominant PCLD is genetically heterogeneous. In conclusion, we propose that, on the basis of our results, genetic screening for PRKCSH gene mutations should be limited to patients either with a positive family history for PCLD or who have severe polycystic liver disease.