Usefulness of combined genetic data in Hungarian families affected by autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary diseases. Mutations of two known genetic loci (PKD1: 16p13.3 and PKD2: 4q21.2) can lead to bilateral renal cysts. The PKD1 locus is the more common (～85%), with a more severe phenotype. Because of the genetic complexity of ADPKD and the size and complexity of the PKD1 gene, pedigree-based linkage analysis is a useful tool for the genetic diagnosis in families with more than one subject affected. We tested linkage or non-linkage to the closely linked DNA markers flanking the PKD1 (D16S663 and D16S291) and one intragenic D16S3252 and PKD2 (D4S1563 and D4S2462) in 30 ADPKD-affected families, to determine the distributions of alleles and the degree of microsatellite polymorphisms (in 91 patients and 125 healthy subjects). To characterize the markers, used heterozygosity levels, polymorphism information content and LOD scores were calculated. The D16S663 marker included 12 kinds of alleles, while D16S291 had 10 alleles and D16S3252 had 8. D4S1563 had 12 alleles and D4S2462 had 11. In a search for a common ancestral relationship, we considered the patients’ alleles with the same repeat number. Only one haplotype was detected in more than one (2) unrelated families. The calculated two-point LOD scores indicated a linkage to PKD1 in 22 families (74%). In four families (13%) with a linkage to PKD2, the patients reached the end-stage renal disease after the age of 65 years. One family was linked to neither gene (3%), and in three families (10%) a linkage to both genes was possible. In the latter three families, the numbers of analyzed subjects were small (4–5), and/or some markers were only partially or non-informative. However, the elderly affected family members exhibited the clinical signs of the PKD1 form in these cases. The new Hungarian population genetic information was compared with available data on other populations.     

Loss of the polycystic kidney disease (PKD1) region of chromosome 16p13 in renal cyst cells supports a loss-of-function model for cyst pathogenesis.

It is not known whether mutations in the PKD1 gene cause autosomal dominant polycystic kidney disease (PKD) by an activating (gain-of-function) or an inactivating (loss-of-function) model. We analyzed DNA from cyst epithelial cells for loss of heterozygosity (LOH) in the PKD1 region of chromosome 16p13 using microsatellite markers. 29 cysts from four patients were studied. Five cysts from three patients had chromosome 16p13 LOH. Four of the cysts had loss of two chromosome 16p13 markers that flank the PKD1 gene. In two patients, microsatellite analysis of family members was consistent with loss of the wild-type copy of PKD1 in the cysts. In the third patient, 16p13 LOH was detected in three separate cysts, all of which showed loss of the same alleles. Chromosome 3p21 LOH was detected in one cyst. No LOH was detected in four other genomic regions. These results demonstrate that some renal cyst epithelial cells exhibit clonal chromosomal abnormalities with loss of the wild-type copy of PKD1. This supports a loss-of-function model for autosomal dominant PKD, with a germline mutation inactivating one copy of PKD1 and somatic mutation or deletion inactivating the remaining wild-type copy.     

The molecular genetic analysis of polycystic kidney disease]

Autosomal dominant polycystic kidney disease (ADPKD) is one of common single gene disorders. The development of molecular genetic techniques has shown that mutant PKD1 gene assigned to ADPKD was closely linked to alpha-globin on the short arm of chromosome 16. This location was established when genetic linkage was found between ADPKD and a highly polymorphic region at the 3' end of the alpha-globin cluster (3' HVR). The discover of genetic linkage markers such as 3' HVR probe has provided a diagnostic test in presymptomatic stage. We performed this diagnostic test using DNA probes in 3 patients with ADPKD of one Japanese family. They also showed PKD1 gene linkage as previously described by Reeders et al. Linkage analysis of the PKD1 gene might be available to diagnostic test of ADPKD. DNA diagnosis of ADPKD however has to be performed carefully because of an ethical standpoint.     

Gene mapping of familial autosomal dominant dilated cardiomyopathy to chromosome 10q21-23.

Dilated cardiomyopathy (DCM) is the most common form of primary myocardial disorder, accounting for 60% of all cardiomyopathies. In 20-30% of cases, familial inheritance can be demonstrated; an autosomal dominant transmission is the usual type of inheritance pattern identified. Previously, genetic heterogeneity was demonstrated in familial autosomal dominant dilated cardiomyopathy (FDCM). Gene localization to chromosome 1 (1p1-1q1 and 1q32), chromosome 3 (3p25-3p22), and chromosome 9 (9q13-9q22) has recently been identified. We report one family with 26 members (12 affected) with familial autosomal dominant dilated cardiomyopathy in which linkage to chromosome 10 at the 10q21-q23 locus is identified. Using short tandem repeat polymorphism (STR) markers with heterozygosity > 70%, 169 markers (50% of the genome) were used before linkage was found to markers D10S605 and D10S201 with a pairwise LOD score = 3.91, theta = 0, penetrance = 100% for both markers. Linkage to 1p1-1q1, 1q32, 3p25-3p22, and 9q13-9q22 was excluded. We conclude that a new locus for pure autosomal dominant FDCM exists, and that this gene is localized to a 9 cM region of 10q21-10q23. The search for the disease causing gene and the responsible mutation(s) is ongoing.     

荧光原位杂交技术快速诊断胎儿常见染色体数目异常

目的探讨荧光原位杂交(FISH)技术在产前诊断中的应用价值。方法采集116名孕妇孕16~23周的羊水标本,应用荧光标记的21号染色体特殊位点探针(21q22,DSCR2)、13号染色体特殊位点探针(13q14,DLEU1)及18号染色体探针、X/Y染色体着丝粒探针(CEP)对未经培养的羊水间期细胞进行FISH检测;同步进行羊水细胞培养,行常规细胞遗传学染色体核型分析。结果 FISH与羊水细胞核型分析相符的染色体数目正常108例,数目异常6例,另各有1例染色体核型分析分别显示为平衡易位、臂内倒位异常,FISH结果显示正常。6例数目异常胎儿引产时抽脐血染色体检查结果与羊水产前诊断结果一致。结论 FISH技术用于快速诊断胎儿常见染色体数目异常,具有简便、快速、特异性强等优点,临床有较高的应用价值。     

荧光原位杂交技术快速诊断胎儿常见染色体数目异常

目的探讨荧光原位杂交（FISH）技术在产前诊断中的应用价值。方法采集116名孕妇孕16~23周的羊水标本,应用荧光标记的21号染色体特殊位点探针（21q22,DSCR2）、13号染色体特殊位点探针（13q14,DLEU1）及18号染色体探针、X/Y染色体着丝粒探针（CEP）对未经培养的羊水间期细胞进行FISH检测;同步进行羊水细胞培养,行常规细胞遗传学染色体核型分析。结果 FISH与羊水细胞核型分析相符的染色体数目正常108例,数目异常6例,另各有1例染色体核型分析分别显示为平衡易位、臂内倒位异常,FISH结果显示正常。6例数目异常胎儿引产时抽脐血染色体检查结果与羊水产前诊断结果一致。结论 FISH技术用于快速诊断胎儿常见染色体数目异常,具有简便、快速、特异性强等优点,临床有较高的应用价值。     

Human gastric adenocarcinoma allelotype on chromosomes 17 and 18

Allelic losses of multiple chromosome loci in gastric adenocarcinoma suggest that inactivation of tumour suppressor genes in these regions may be important for tumourigenesis. To define deletion intervals and find candidate tumour suppressor genes involved in gastric adenocarcinoma pathogenesis, a genome-wide search for loss of heterozygosity (LOH) was conducted in 45 patients with primary gastric adenocarcinoma. Investigations using 29 microsatellite markers spanning chromosomes 17 and 18 showed allelic deletion in 29 (64%) specimens at one or more loci. Five LOH overlap regions, three newly identified as deletion regions, were defined: RI, D17S831 - D17S921 at 17p12-13.3; RII, D17S1868 - D17S787 at 17q21.3-22; RIII, D17S785 - D17S928 at 17q25.3; RIV, D18S61 - D18S1161 at 18q22; and RV, D18S462 - D18S70 at 18q22-q23. Eleven (24%) patients with chromosome 17 allelic loss also showed LOH on 18q, with at least one region of overlapping. LOH mapping showed allelic losses were widespread on both chromosomes and suggests the possibility that multiple tumour suppressor genes, including one or more that are unknown, might be inactivated in the aetiology of gastric adenocarcinoma.     

Chromosomal abnormalities in myelodysplastic syndromes and acute myeloid leukemia

Clonal chromosome abnormalities are found in more than half the patients with hematologic malignancies. Karyotype is an independent prognostic factor in these patients. Cytogenetic findings correlate significantly with morphologic, immunologic, and clinical features as well as response to treatment, remission duration, and survival. The number of different cytogenetic abnormalities is enormous; however, many cytogenetic findings frequently occur in a given disease (e.g., abnormalities of 5 or 7 in 75% to 90% of patients with therapy-related AML). Some abnormalities are found only in myeloid malignancies, for example, the t(8;21)(q22;q22) and rearrangements of chromosome 16q22, both of which have a good prognosis. Other abnormalities usually are found in both myeloid and lymphoid malignancies, for example, the t(4;11)(q21;q23) and t(9;22)(q34;q11), both of which have a poor prognosis. The Human Gene Mapping Conferences have compiled much cytogenetic data and produced several interesting correlations in myeloid malignancies: rearrangements of 3q21-26 with myeloid proliferations associated with environmental exposure (similar to abnormalities of 5q, 7q, 12p, and 17q), aberrations of 12p, 11q13 and 11q23 with both myeloid and lymphoid disorders, and the lack of myeloid involvement and abnormalities of chromosomes 14 and 18. In conclusion, cytogenetic analysis of neoplastic cells at diagnosis for patients with MDS, AML, and SAML is required for appropriate diagnosis and treatment. The use of chromosome abnormalities to separate patients into high- and low-risk groups eventually may allow us to be more effective in selecting curative therapy.     

遗传性丙酮酸激酶缺乏症的诊疗现状

遗传性丙酮酸激酶缺乏症(PKD)是由人肝红细胞丙酮酸激酶(PKLR)基因突变导致的一种隐性遗传的纯合子或杂合子突变疾病.PKLR基因位于染色体1q21,目前发现的突变类型已超过200种.PKD常导致遗传性非球形红细胞溶血性贫血(HNHA)发生.笔者对PKD的诊断、治疗现状进行综述.     

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.     

The low-incidence red cell antigen Wra: genetic studies

Studies of 91 individuals in three families allowed a genetic-linkage analysis of the gene governing the production of the low-incidence red cell antigen Wra and provided evidence that Wra is not a member of the Scianna, Landsteiner-Wiener, Chido/Rodgers, or XK blood group systems, and that the "WR" locus is excluded from autosomal sites or regions 1p34-p22.1, 1p21-q23, 1q32, 2p25, 3q21, 4q28-q32, 6p24-q12, 9q34.1-q34.2, 13q14.1-q14.2, 14q24.3-q32.1, 14q32.33, 16p13, 16q22.1, and 21q21-q22.1. "WR" is also excluded from within specified genetic distances of chromosomes 8 (GPT), 18 (JK), 19 (C3), 20 (ADA), and 22 (P1) loci, which brings its exclusion to approximately 10 percent (320cM) of the total genetic map of the genome. The possibility that "WR" is pseudoautosomal is deemed to be highly unlikely.     

Prenatal detection of a de novo Yqh-acrocentric translocation

OBJECTIVES: To identify the extra chromosomal material on 46,XX,21p+ for prenatal diagnosis. DESIGN AND METHODS: Conventional cytogenetic studies using GTG (G bands by trypsin using Giemsa) and CBG (C bands by barium hydroxide using Giemsa) techniques were performed on chromosomes at metaphase obtained from cultured amniocytes and parental blood lymphocytes. Molecular cytogenetic techniques, QF-PCR (quantitative fluorescent polymerase chain reaction), FISH (fluorescent in-situ hybridization), and DA-DAPI (Distamycin A and 4,6-diamino-2-phenylindole) staining, were then used to clarify the extra material present on fetal chromosome 21 p. RESULTS: The extra material on fetal chromosome 21 p has originated from Yqh, most likely at PAR2 (the secondary pseudoautosomal region). The karyotype should be 46,XX,der(21)t(Y;21)(q12;p13)de novo.ish der(21)t(Y;21)(q12;p13) (EST Cdy16c07+). CONCLUSION: This case demonstrates the usefulness of molecular techniques in the investigation of rare chromosomal rearrangements.     

卵巢癌组织17号染色体位点的微卫星不稳定性的研究

目的 探讨卵巢癌组织微卫星不稳定性（Microsatellite Instability,MIN)的表现。方法 在23例卵巢癌新鲜组织和自身癌旁正常组织的DNA中,用聚合酶链反应（PCR）扩增17号染色体上5个微卫星位点,用单链构象多态性（Single Strand Conformation Polymorphism,SSCP)分析法检测微卫星不稳定性（MIN）,并用银染方法显示结果。结果 在23例卵巢癌组织中均有不同程度的MIN发生,其中浆液性卵巢癌阳性率明显高于其他类型卵巢癌;Ⅲ-Ⅳ期肿瘤微卫星不稳定性高于Ⅰ－Ⅱ期肿瘤。在17号染色体长臂上的3个微卫星位点D17S855、D17S806和D17S579的MIN的发生率分别为4／23、7／23、6／23,短臂上2个位点D17S513和TP53的MIN的发生率分别为2／23和4／23,长臂的阳性率明显高于短臂,表明长臂比短臂更不稳定。有4例病例在短臂和长臂处均出现MIN,表明17号染色体的长臂和短臂出现MIN是卵巢癌普遍发生的现象。结论 17号染色体定位于BRCA1附近的3个微卫星位点以及p53附近的微卫星位点均频繁地出现MIN。证实了频繁发生微卫星不稳定的染色体区域附近,可能存在抑癌基因,并且有可能引起抑癌基因功能的丧失。位于端粒处的D17S513发生MIN,可以推测在端粒至p53的区域可能存在一个新的抑癌基因。     

Practical genetics for autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common mendelian disorder of the kidney and accounts for ~5% of end-stage renal disease in North America. It is characterized by focal development of renal cysts which increase in number and size with age. Mutations of PKD1 and PKD2 account for most cases. Although the clinical manifestations of both gene types overlap completely, PKD1 is associated with more severe disease than PKD2, with larger kidneys and earlier onset of end-stage renal disease. Furthermore, marked within-family renal disease variability is well documented in ADPKD and suggests a strong modifier effect from as yet unknown genetic and environmental factors. In turn, the significant inter- and intra-familial renal disease variability poses a challenge for diagnosis and genetic counseling. In general, renal ultrasonography is commonly used for the diagnosis, and age-dependent criteria have been defined for subjects at risk of PKD1. However, the utility of the PKD1 ultrasound criteria in the clinical setting is unclear since their performance characteristics have not been defined for the milder PKD2 and the gene type for most test subjects is unknown. Recently, highly predictive ultrasound diagnostic criteria have been derived for at-risk subjects of unknown gene type. Additionally, both DNA linkage and gene-based direct sequencing are available for the diagnosis of ADPKD, especially in subjects with equivocal imaging results, a negative or indeterminate family history, or in younger at-risk individuals being evaluated as potential living related kidney donor. This review will highlight the utility and limitations of clinical predictors of gene types, imaging- and molecular-based diagnostic tests, and present an integrated approach for evaluating individuals suspected to have ADPKD.     

A novel ATP1A2 gene mutation in an Irish familial hemiplegic migraine kindred

OBJECTIVE: We studied a large Irish Caucasian pedigree with familial hemiplegic migraine (FHM) with the aim of finding the causative gene mutation. BACKGROUND: FHM is a rare autosomal-dominant subtype of migraine with aura, which is linked to 4 loci on chromosomes 19p13, 1q23, 2q24, and 1q31. The mutations responsible for hemiplegic migraine have been described in the CACNA1A gene (chromosome 19p13), ATP1A2 gene (chromosome 1q23), and SCN1A gene (chromosome 2q24). METHODS: We performed linkage analyses in this family for chromosome 1q23 and performed mutation analysis of the ATP1A2 gene. RESULTS: Linkage to the FHM2 locus on chromosome 1 was demonstrated. Mutation screening of the ATP1A2 gene revealed a G to C substitution in exon 22 resulting in a novel protein variant, D999H, which co-segregates with FHM within this pedigree and is absent in 50 unaffected individuals. This residue is also highly conserved across species. CONCLUSIONS: We propose that D999H is a novel FHM ATP1A2 mutation.     

Pkd1 regulates immortalized proliferation of renal tubular epithelial cells through p53 induction and JNK activation

Autosomal dominant polycystic kidney disease (ADPKD) is the most common human monogenic genetic disorder and is characterized by progressive bilateral renal cysts and the development of renal insufficiency. The cystogenesis of ADPKD is believed to be a monoclonal proliferation of PKD-deficient (PKD(-/-)) renal tubular epithelial cells. To define the function of Pkd1, we generated chimeric mice by aggregation of Pkd1(-/-) ES cells and Pkd1(+/+) morulae from ROSA26 mice. As occurs in humans with ADPKD, these mice developed cysts in the kidney, liver, and pancreas. Surprisingly, the cyst epithelia of the kidney were composed of both Pkd1(-/-) and Pkd1(+/+) renal tubular epithelial cells in the early stages of cystogenesis. Pkd1(-/-) cyst epithelial cells changed in shape from cuboidal to flat and replaced Pkd1(+/+) cyst epithelial cells lost by JNK-mediated apoptosis in intermediate stages. In late-stage cysts, Pkd1(-/-) cells continued immortalized proliferation with downregulation of p53. These results provide a novel understanding of the cystogenesis of ADPKD patients. Furthermore, immortalized proliferation without induction of p53 was frequently observed in 3T3-type culture of mouse embryonic fibroblasts from Pkd1(-/-) mice. Thus, Pkd1 plays a role in preventing immortalized proliferation of renal tubular epithelial cells through the induction of p53 and activation of JNK.     

Molecular genetics of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a common Mendelian disorder, occurring in approximately 1 in 1000 births and accounting for 8% to 10% of cases of end-stage renal disease (ESRD). Mutations of 2 genes, PKD1 and PKD2, account for the disease in approximately 80% to 85% and 10% to 15% of families respectively. The gene products (polycystin 1 and 2) of PKD1 and PKD2 are plasma membrane proteins and components of a novel signalling pathway that regulates epithelial cell growth and differentiation. Significant inter- and intrafamilial renal disease variability in ADPKD has been well documented and is influenced by both germline and somatic genetic events. Specifically, genetic locus heterogeneity and 2 rare Mendelian syndromes have been shown to strongly influence the variability of interfamilial renal disease, and as-yet-unknown genetic and environmental factors likely modify both inter- and intrafamilial renal disease severity. Furthermore, individual cyst formation in ADPKD represents an aberration of monoclonal growth triggered by somatic PKD1 or PKD2 mutations within individual epithelial cells. Current studies are in progress to identify major genetic and environmental modifiers of renal disease variability. A thorough knowledge of these determinants will allow better patient risk assessment and development of mechanism-based therapy in ADPKD.     

Towards understanding the polycystins

Autosomal dominant polycystic kidney disease (ADPKD) is a very common inherited disease caused by mutations in PKD1 or PKD2 genes characterized by progressive enlargement of fluid-filled cysts and loss of renal function [1]. Previous studies proposed a role for human polycystin-1 in renal morphogenesis acting as a matrix receptor in focal adhesions and for polycystin-2 as a putative calcium channel [2, 3]. The genome of Caenorhabditis elegans contains 2 new members of the polycystin family: lov-1, the homolog for PKD1; and pkd-2, the homolog for PKD2 [4; this paper]. Mutation analysis in C. elegans showed similarly compromised male mating behaviors in all single and double lov-1 and pkd-2 mutants, indicating their participation in a single genetic pathway. Expression analysis localized LOV-1 and PKD-2 to the ends of sensory neurons in male tails and to the tips of CEM neurons in the head, consistent with functions as chemo- or mechanosensors. Human and C. elegans PKD1 and PKD2 homologs, transfected into mammalian renal epithelial cells, co-localized with paxillin in focal adhesions suggesting function in a single biological pathway. Based on the role of polycystins in C. elegans sensory neuron function and the conservation of PKD pathways we suggest that polycystins act as sensors of the extracellular environment, initiating, via focal adhesion assembly, intracellular transduction events in neuronal or morphogenetic processes.     

Rearrangements of the tal-1 locus as clonal markers for T cell acute lymphoblastic leukemia.

Normal and aberrant immune receptor gene assembly each produce site-specific DNA rearrangements in leukemic lymphoblasts. In either case, these rearrangements provide useful clonal markers for the leukemias in question. In the t(1;14)(p34;q11) translocation associated with T cell acute lymphoblastic leukemia (T-ALL), the breakpoints on chromosome 1 interrupt the tal-1 gene. A site-specific deletion interrupts the same gene in an additional 26% of T-ALL. Thus, nearly one-third of these leukemias contain clustered rearrangements of the tal-1 locus. To test whether these rearrangements can serve as markers for residual disease, we monitored four patients with T-ALL; three of the leukemias contained a deleted (tald) and one a translocated (talt) tal-1 allele. These alleles were recognized by a sensitive amplification/hybridization assay. tald alleles were found in the blood of one patient during the 4th mo of treatment but not thereafter. Using a quantitative assay to measure the fraction of tald alleles in DNA extracts, we estimated that this month 4 sample contained 150 tald copies per 10(6) genome copies. The patient with t(1;14)(p34;q11) (talt) leukemia developed a positive assay during the 20th mo of treatment. By standard criteria, all four patients remain in complete remission 11-20 mo into treatment. We conclude that tal-1 rearrangements provide useful clonal markers for approximately 30% of T-ALLs.