Autosomal dominant polycystic kidney disease

An Italian family with autosomal dominant polycystic kidney disease unlinked to either the PKD1 or PKD2 gene

We describe a family with autosomal dominant polycystic kidney disease in which molecular typing with closely linked markers for the PKD1 and PKD2 genes indicated absence of linkage. Thus, a third still unknown locus appears likely to be involved in disease development. This is the fourth "PKD3-linked" family described to date and the first from Italy.

Autosomal dominant polycystic kidney disease (ADPKD) in an Italian family carrying a novel nonsense mutation and two missense changes in exons 44 and 45 of the PKD1 Gene

Sixty-seven Italian patients with autosomal dominant polycystic kidney disease (ADPKD) were screened for mutations in the 3' unique region of the PKD1 gene, using heteroduplex DNA analysis. Novel aberrant bands were detected in 3 patients from the same family. DNA sequencing showed a C to T transition in exon 44 (C12269T), resulting in a premature stop codon (R4020X), predicted to impair the synthesis of the putative intracytoplasmic C-terminus tail of the PKD1 protein, polycystin. The mutation also generates a novel DdeI restriction site, and the abnormal restriction pattern was observed both on genomic DNA and on cDNA from the affected relatives, indicating that this is indeed the pathogenetic molecular lesion. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on lymphocyte mRNA showed that the mutant transcript is normally present and stable. No aberrantly spliced mRNAs were detected. Interestingly, the mutant PKD1 chromosome in this family also bears two missense mutations downstream (A12341G and C12384T), not found in the other ADPKD families studied.

Evidence that two phenotypically distinct mouse PKD mutations, bpk and jcpk, are allelic

Numerous mouse models of polycystic kidney disease (PKD) have been described. All of these diseases are transmitted as single recessive traits and in most, the phenotypic severity is influenced by the genetic background. However, based on their genetic map positions, none of these loci appears to be allelic and none are candidate modifier loci for any other mouse PKD mutation. Previously, we have described the mouse bpk mutation, a model that closely resembles human autosomal recessive polycystic kidney disease. We now report that the bpk mutation maps to a 1.6 CM interval on mouse Chromosome 10, and that the renal cystic disease severity in our intersubspecific intercross progeny is influenced by the genetic background. Interestingly, bpk co-localizes with jcpk, a phenotypically-distinct PKD mutation, and complementation testing indicates that the bpk and jcpk mutations are allelic. These data imply that distinct PKD phenotypes can result from different mutations within a single gene. In addition, based on its map position, the bpk locus is a candidate genetic modifier for jck, a third phenotypically-distinct PKD mutation.

PKD2, a gene for polycystic kidney disease that encodes an integral membrane protein

A second gene for autosomal dominant polycystic kidney disease was identified by positional cloning. Nonsense mutations in this gene (PKD2) segregated with the disease in three PKD2 families. The predicted 968-amino acid sequence of the PKD2 gene product has six transmembrane spans with intracellular amino- and carboxyl-termini. The PKD2 protein has amino acid similarity with PKD1, the Caenorhabditis elegans homolog of PKD1, and the family of voltage-activated calcium (and sodium) channels, and it contains a potential calcium-binding domain.

The sea urchin sperm receptor for egg jelly is a modular protein with extensive homology to the human polycystic kidney disease protein, PKD1

During fertilization, the sea urchin sperm acrosome reaction (AR), an ion channel-regulated event, is triggered by glycoproteins in egg jelly (EJ). A 210-kD sperm membrane glycoprotein is the receptor for EJ (REJ). This conclusion is based on the following data: purified REJ binds species specifically to EJ dotted onto nitrocellulose, an mAb to REJ induces the sperm AR, antibody induction is blocked by purified REJ, and purified REJ absorbs the AR-inducing activity of EJ. Overlapping fragments of REJ cDNA were cloned (total length, 5,596 bp). The sequence was confirmed by microsequencing six peptides of mature REJ and by Western blotting with antibody to a synthetic peptide designed from the sequence. Complete deglycosylation of REJ followed by Western blotting yielded a size estimate in agreement with that of the mature amino acid sequence. REJ is modular in design; it contains one EGF module and two C-type lectin carbohydrate-recognition modules. Most importantly, it contains a novel module, herein named the REJ module (700 residues), which shares extensive homology with the human polycystic kidney disease protein (PKD1). Mutations in PKD1 cause autosomal dominant polycystic kidney disease, one of the most frequent genetic disease of humans. The lesion in cellular physiology resulting from mutations in the PKD1 protein remains unknown. The homology between REJ modules of the sea urchin REJ and human PKD1 suggests that PKD1 could be involved in ionic regulation.

High incidence of common bile duct dilatation in autosomal dominant polycystic kidney disease patients

Two autosomal dominant kidney disease (ADPKD) patients with cholecystitis or communicating extrahepatic dilatation of the common bile duct accompanied by tiny common bile duct stones prompted us to examine the incidence of gall stone disease and dilatation of the common bile duct in ADPKD patients. Computed tomography scans were examined retrospectively in 55 ADPKD patients and 55 age-, gender-, and duration of dialysis-matched non-ADPKD patients. The incidence of calcium-containing gall stones found on tomography scans was the same: eight of the 55 ADPKD patients and nine of the 55 non-ADPKD patients. However, common bile duct dilatation, defined as measuring more than 7 mm in diameter at the pancreatic head on CT scans, was found more frequently in the ADPKD patients (22 patients; 40.0%) than in the non-ADPKD patients (5 patients; 9.1%) (P = 0.0002). These results suggest that the high incidence of intrapancreatic common bile duct dilatation in ADPKD is a previously undescribed sign of extracellular matrix remodeling in ADPKD.

Hepatic cystic disease in an adult polycystic kidney disease transplant population

BACKGROUND

A study of the incidence of polycystic liver in a transplant population and an assessment of the impact of this disease on the group was undertaken. Clinical presentation, investigation and treatment of hepatic polycystic disease are explored.

METHODS

The study examined the morbidity incurred by polycystic liver disease in patients, patient and graft survival, incidence of hepatic cysts and presentation, investigation and management of morbid hepatic cystic disease. One hundred and eleven patients were studied.

RESULTS

It was found that hepatic cysts occurred in the majority of patients that underwent transplants for renal failure because of polycystic kidney disease at this institution. Symptomatic hepatic cystic disease was found to be primarily responsible for three deaths and affected between 15 and 20% of the group. Gall bladder disease was found to be associated with highly symptomatic hepatic cystic disease.

CONCLUSION

Hepatic cystic disease is common in patients that have had kidney transplants because of polycystic kidney disease. Morbidity is likely to increase as patients survive for longer periods. Cholecystectomy should be considered in patients with significant hepatic cystic disease.

Laparoscopy for adult polycystic kidney disease: a promising alternative

The purpose of this study was to evaluate the efficacy of laparoscopy in managing patients with abdominal symptoms from autosomal dominant polycystic kidney disease (ADPKD). From April 1993 to July 1995, four patients with ADPKD underwent seven laparoscopic procedures: five cyst decortications were performed in two patients using a laparoscopic ultrasound unit and two laparoscopic nephrectomies were performed in two patients with end-stage renal failure. The mean operative time was 207 minutes for laparoscopic cyst decortication and 272 minutes for laparoscopic nephrectomy. The two nephrectomy specimens were 2,200 g and 1,750 g, respectively. The mean intraoperative blood loss was 85 mL. The patients resumed their oral intake within 10 hours after laparoscopic cyst decortication and within 16 hours after laparoscopic nephrectomy. The mean amount of parenteral analgesics required postoperatively was 12 mg morphine sulfate for cyst decortication and 30 mg morphine sulfate for nephrectomy. The mean hospital stay was 3 days for cyst decortication and 3.5 days for nephrectomy. The patients returned to their usual activities after an average of 2 weeks. Based on pain analog scales, all the patients have shown marked reduction in their symptoms (average, 90%) during an average follow-up period of 6.6 months. Laparoscopic cyst decortication and nephrectomy are effective minimally invasive treatment options for patients with adult polycystic kidney disease who are experiencing abdominal symptoms due to marked renal enlargement. We believe that by using a laparoscopic ultrasound unit, most renal cysts may be safely removed, and if need be, even "giant" kidneys can be removed laparoscopically. To the best of our knowledge, the two nephrectomy specimens in this study represent the largest kidneys removed laparoscopically to date and the first laparoscopic nephrectomies in ADPKD patients.

A role for CFTR in human autosomal dominant polycystic kidney disease

Human autosomal dominant polycystic kidney disease (ADPKD) is the most common lethal dominant hereditary disorder characterized by enormous renal enlargement and the development of multiple cysts originating from nephrons. We investigated the pathogenesis of cyst formation in ADPKD by using patch-clamp and immunocytochemical techniques. Adenosine 3',5'-cyclic monophosphate-activated Cl- currents are present in primary cultures of ADPKD cells and have characteristics such as a linear current-voltage relation, insensitivity to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, sensitivity to glibenclamide and diphenylamine carboxylic acid, and an anion selectivity sequence of Br- > Cl- > I- > glutamate, all of which are identical to cystic fibrosis transmembrane conductance regulator (CFTR). With the use of CFTR antibodies raised against the regulatory and first nucleotide-binding domains, CFTR was detected in primary cultures of ADPKD cells. Similar results were obtained in vivo in cyst-lining epithelial cells in ADPKD kidneys, where staining was seen associated with the apical membrane regions. These data indicate that the CFTR Cl- channel exists in apical membranes of ADPKD cells and may play an important role in cyst formation or enlargement.

Intracranial cysts in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder well known for its association with intracranial aneurysms. A series of patients with ADPKD who were screened for the presence of an intracranial aneurysm were reviewed and found to include an unexpectedly high number with intracranial arachnoid cysts. Among 247 patients with ADPKD who underwent magnetic resonance imaging (180 cases) or high-resolution contrast-enhanced computerized tomography (67 cases), there were 151 women and 96 men with a mean age of 44 years. Intracranial arachnoid cysts were found in 20 patients (8.1%) with ADPKD compared to two (0.8%) in a control group without ADPKD matched for age, sex, and method of imaging (p < 0.0001). Multiple intracranial arachnoid cysts were found in two patients. Polycystic liver disease was present in 17 (85.0%) of the 20 patients with intracranial arachnoid cysts compared to 119 (52.4%) of the 227 patients without (p < 0.004). Pineal cysts were found in two patients (0.8%) and choroid plexus cysts were found in three patients (1.2%) but this was not different from the control population. None of the intracranial cysts was symptomatic and none was treated surgically. Intracranial arachnoid cysts are a relatively frequent incidental finding in patients with ADPKD, providing further support for the systemic nature of this disease. In the authors' experience with approximately 1500 patients with ADPKD, no complication has been encountered from an intracranial arachnoid cyst, suggesting that asymptomatic intracranial arachnoid cysts in patients with ADPKD require no treatment.

Congenital nephropathies and uropathies

Although congenital nephropathies and uropathies only represent a fraction of possible genitourinary diseases detected during childhood, they have serious and sometimes avoidable morbidity and mortality. Advances in genetic, molecular, and cellular biology research continue to better define embryologic insults to normal organogenesis and offer the promise that many of these conditions might be avoided in the future. For now, awareness of these entities and their varied presentations and manifestations is crucial so that prompt evaluation and aggressive multidisciplinary management assures the affected child optimal growth and development.

Polycystic kidney disease: etiology, pathogenesis, and treatment

Once viewed as hopelessly incurable disorders and the dustbin for careers in academic medicine, the polycystic kidney diseases have emerged as prime targets of pathophysiologic study and palliative and definitive treatment in the era of molecular medicine. Polycystic kidney disease (PKD) may be hereditary or acquired. The major inherited types are autosomal dominant (AD) and autosomal recessive (AR). ADPKD is caused by at least two (and possibly three) genes located on separate chromosomes, while ADPKD-1 is due to a 14 kb transcript in a duplicated region on the short arm of chromosome 16 very near the alpha-globin gene cluster and the gene for one form of tuberous sclerosis. ADPKD-2 has been assigned to the long arm of chromosome 4. ARPKD is due to a mutated gene on both copies of the long arm of chromosome 6. Cysts originate in renal tubules. Proliferation of tubule epithelial cells modulated by endocrine, paracrine, and autocrine factors is a major element in the pathogenesis of renal cystic diseases. In addition, fluid that is abnormally accumulated within the cysts is derived from glomerular filtrate and, to a greater extent, by transepithelial fluid secretion. Abnormal synthesis and degradation of matrix components associated with interstitial inflammation are additional features in the pathogenesis of renal cystic diseases. The ADPKD genotypes are characterized by bilateral kidney cysts, hypertension, hematuria, renal infection, stones, and renal insufficiency. ADPKD is a systemic disorder; cysts appear with decreasing frequency in the kidneys, liver, pancreas, brain, spleen, ovaries, and testis. Cardiac valvular disorders, abdominal and inguinal hernias, and aneurysms of cerebral and coronary arteries and aorta are also associated with ADPKD. Treatment is supportive: dietary regulation of salt and protein intake, control of hypertension and renal stones, and dialysis and transplantation at the end stage. ARPKD is a relatively rare disease that causes clinical symptoms at birth, with significant mortality in the first month of life. The cysts develop primarily in the collecting ducts because of a failure in the maturation process. Early complications include Potter's syndrome; excessive size of the kidneys, causing respiratory dysfunction; hypertension; and renal insufficiency. Hepatic fibrosis is an associated extrarenal problem that results in significant morbidity in young children and adolescents. Treatment includes supportive care, dialysis, and renal transplantation. Acquired cysts (solitary/simple) are commonplace in older persons. Multiple cysts may be seen in association with potassium deficiency, congenital disorders, metabolic diseases, and toxic renal injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Isolation and characterization of a novel zinc-finger protein with transcription repressor activity

To identify genes that can repress the expression of growth regulatory molecules, a human fetal cDNA library was screened with a degenerate oligonucleotide that corresponds to the conserved stretch of 6 amino acids connecting successive zinc-finger regions in the Wilms' tumor suppressor/Egr-1 family of DNA-binding proteins. One clone, designated zinc-finger protein 174 (ZNF174), corresponds to a putative transcription factor with three zinc fingers and a novel finger-associated domain, designated the SCAN box. The three Cys2-His2-type zinc fingers are positioned at the carboxyl terminus, while the 65-amino acid finger-associated SCAN box is located near the amino terminus. Chromosomal localization using somatic cell hybrid analysis and fluorescent in situ hybridization mapped the gene for ZNF174 to human chromosome 16p13.3. The 2.5-kilobase transcript from this gene is expressed in a variety of human organs, but most strongly in adult testis and ovary. Fusion of the upstream regulatory region of ZNF174 to the DNA-binding domain of GAL4 revealed that the gene could confer a repression function on the heterologous DNA-binding domain. ZNF174 selectively repressed reporter activity driven by the platelet-derived growth factor-B chain and transforming growth factor-beta 1 promoters and bound to DNA in a specific manner. This member of the C2H2-type zinc-finger family is a novel transcriptional repressor.

Animal models of polycystic kidney disease

Polycystic kidney disease (PKD) is one of the most prevalent causes of heritable renal failure. The disease is characterized by the occurrence of numerous fluid-filled cysts within the parenchyma of kidney. The cysts are epithelial in origin and expand in size, leading to crowding of normal kidney tissue. Ultimately, there is gross enlargement of the kidneys with loss of normal functions, and death usually occurs because of complications related to renal failure. Animal models of polycystic kidney disease are proving to be extremely useful for studying the molecular basis of renal cyst formation and for the isolation of genes carrying the mutations. This article describes the various animal models of polycystic kidney disease, spontaneously and experimentally derived, that have recently been identified.

The evaluation and selection of living kidney donors

As the number of living kidney donations in the United States increases, it is important to continue to assess the manner in which potential living donors are evaluated and selected. Ethical issues can be framed using principles that are understandable to patients and physicians. Existing evidence suggests that, for most suitable donors, the short- and long-term risks of kidney donation are small enough to be outweighed by the potential benefits to the donor and recipient. A thorough but efficient evaluation of potential living donors, as outlined in this review, can effectively minimize the risks. However, mechanisms to provide long-term follow-up of all living donors are still needed. Appropriate surveillance mechanisms not only will minimize any long-term risks to individuals who have already donated a kidney but will also provide the data needed to accurately assess the risk, however small, for future donors. With or without these data, living donations will likely continue to play an increasingly important role in renal transplantation.

Apoptosis and loss of renal tissue in polycystic kidney diseases

BACKGROUND

Polycystic kidney disease is characterized by the enlargement of renal cysts, interstitial fibrosis, and gradual loss of normal renal tissue in association with progressive deterioration of renal function. The process causing the progressive loss of renal tissue is unknown, but it could be the result of a form of programmed cell death known as apoptosis.

METHODS

We assayed apoptotic DNA fragmentation in normal and polycystic kidneys biochemically by gel electrophoresis and histochemically by in situ end-labeling. A DNA-specific dye, Hoechst 33258, was used to detect morphologic apoptosis in renal samples from patients with normal kidneys, polycystic kidney disease, and other kidney diseases.

RESULTS

Apoptotic DNA fragmentation was detected in polycystic kidneys from 5 patients without renal failure and 11 patients with renal failure but not in kidneys from 12 patients with no renal disease. In situ end-labeling revealed apoptotic cells in glomeruli, in cyst walls, and in both cystic and noncystic tubules of the polycystic kidneys. No tubular apoptosis was detected in renal-biopsy specimens from five patients with IgA nephropathy, three patients with nephrosclerosis, two patients with focal glomerulosclerosis, one patient with diabetic nephropathy, six patients with acute tubular necrosis, or four patients with acute and four patients with chronic renal-transplant rejection. The capacity of polycystic kidney cells to undergo apoptosis was retained in vitro in the absence of uremia, ischemia, and other confounding pathologic conditions.

CONCLUSIONS

Apoptotic loss of renal tissue may be associated with the progressive deterioration of renal function that occurs in patients with polycystic kidney disease.

The polycystic kidney disease 1 (PKD1) gene encodes a novel protein with multiple cell recognition domains

Characterization of the polycystic kidney disease 1 (PKD1) gene has been complicated by genomic rearrangements on chromosome 16. We have used an exon linking strategy, taking RNA from a cell line containing PKD1 but not the duplicate loci, to clone a cDNA contig of the entire transcript. The transcript consists of 14,148 bp (including a correction to the previously described C terminus), distributed among 46 exons spanning 52 kb. The predicted PKD1 protein, polycystin, is a glycoprotein with multiple transmembrane domains and a cytoplasmic C-tail. The N-terminal extracellular region of over 2,500 aa contains leucine-rich repeats, a C-type lectin, 16 immunoglobulin-like repeats and four type III fibronectin-related domains. Our results indicate that polycystin is an integral membrane protein involved in cell-cell/matrix interactions.

Cyst fluid from a murine model of polycystic kidney disease stimulates fluid secretion, cyclic adenosine monophosphate accumulation, and cell proliferation by Madin-Darby canine kidney cells in vitro

Cyst fluids from subjects with autosomal dominant polycystic kidney disease (ADPKD) cause polarized monolayers of MDCK cells to secrete fluid toward the apical compartment in vitro. To determine the extent to which secretagogue accumulation may be a general feature of polycystic diseases, cyst fluid from mice with a slowly progressive form of hereditary PKD (DBA/2FG-pcy/pcy) was added to polarized MDCK monolayers. Basolateral application of cyst fluids (diluted with culture medium to 15% final concentration) from 13 different animals 16 to 35 weeks old increased the fluid secretion rate from a baseline of 0.023 +/- 0.003 to 0.111 +/- 0.017 microL/cm2/h (P < 0.005). There was a direct relation between the concentration of cyst fluid and the rate of net fluid secretion. The secretory activity of cyst fluid was not altered by pronase treatment or boiling. Cyst fluid (10%) added to the basolateral surfaces of polarized MDCK monolayers for 24 hours increased cell cyclic adenosine monophosphate (AMP) levels from a baseline of 6.3 +/- 0.2 to 17.3 +/- 0.3 pmoles/monolayer (n = 3, P < 0.05). The capacity of cyst fluid to increase cyclic AMP levels was not changed by pronase treatment or boiling. There was a direct relation between the level of cellular cyclic AMP and the rate of transepithelial fluid secretion caused by cyst fluid. Cyst fluid increased thymidine incorporation by Madin-Darby canine kidney (MDCK) cells to an extent equal to that caused by epidermal growth factor and caused MDCK cells to form cysts in collagen matricies.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for a third genetic locus for autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous disease with loci on chromosomes 16p and 4q. It has a moderately high spontaneous mutation rate, although the relative frequency of such mutations at each gene locus is unknown. In studying genetic heterogeneity in the French-Canadian population, we identified a family in which a classical clinical presentation of ADPKD resulted from a mutation at a locus genetically distinct from either of the previously described loci for this disease. This suggests the existence of a third genetic locus for ADPKD.

New mouse model for polycystic kidney disease with both recessive and dominant gene effects

In the course of studying the genetics of chlorambucil mutagenesis, we have uncovered a new model for autosomal polycystic kidney disease (PKD). In the homozygous condition, the gene, jcpk, causes a very severe disease characterized by cysts in all segments of the nephron. Death usually occurs before 10 days of age. Extrarenal involvement was also noted; enlarged bile ducts, pancreatic ducts, and gall bladder often accompanied the PKD. In addition, approximately 25% of the aged +/jcpk heterozygotes show evidence of glomerulocystic disease. This gene maps to Chromosome 10 between two DNA markers, D10Mit20 and D10Mit42. Because this gene causes extrarenal abnormalities and because it has a heterozygote effect, it may be an informative animal model for the commonly occurring human adult dominant PKD.

Methylprednisolone retards the progression of inherited polycystic kidney disease in rodents

Polycystic kidney disease in adult laboratory animals and humans is associated with enlarged kidneys and a progressive decline of renal function, resulting in death from uremia. Interstitial inflammation and fibrosis typically are observed in association with the development of renal insufficiency. To determine whether amelioration of interstitial inflammation and fibrosis may diminish cyst expansion/kidney enlargement and stabilize renal function, we administered methylprednisolone, an anti-inflammatory drug with antifibrogenic effects, to mice and rats with hereditary polycystic kidney disease. The experiment was repeated once for each species. Mice were studied both in America and in Japan. Weanling male and female mice (DBA/FG pcy/pcy [cystic] and +/+ [normal], n = 87 and 20, respectively) and rats (Han:SPRD Cy/+ and +/+, n = 70 and 33, respectively) were administered methylprednisolone (1 to 2 mg/kg/d) in the drinking water for 100 days (mice) or 42 days (rats). Control animals drank distilled water. In normal DBA +/+ mice, methylprednisolone had no effect on serum urea nitrogen (SUN) levels, kidney weight, or kidney/body weight. Untreated male and female mice developed cystic kidneys and azotemia to an equal extent. Methylprednisolone administered in America to mice with renal cystic disease decreased kidney weight, kidney/body weight, SUN levels, volume density of cysts, and severity of interstitial fibrosis. In Japan, methylprednisolone decreased kidney weight and SUN levels of animals with cystic disease, but the effect on kidney/body weight did not reach statistical significance. In contrast to mice, male rats developed more severe renal cystic changes and were more azotemic than female rats. Methylprednisolone administered to male rats with cystic disease decreased SUN levels, kidney weight, kidney/body weight, volume density of cysts, and severity of interstitial fibrosis. Methylprednisolone had no effect on kidney/body weight or SUN levels in female rats with renal cystic disease. In normal Han:SPRD (+/+) rats of both sexes, kidney and body weight were decreased by methylprednisolone, but kidney/body weight and SUN levels were unchanged. On the basis of this study, we conclude that methylprednisolone decreased the extent of renal enlargement, reduced renal interstitial fibrosis, and preserved kidney function in mice and rats with relatively severe forms of inherited polycystic kidney disease.

Gene linkage analysis and DNA based detection of autosomal dominant polycystic kidney disease (ADPKD) in a newborn infant. Case report

Bilateral polycystic kidneys were detected by ultrasound at 23 weeks gestation in a male fetus. Bilateral renal cysts were subsequently also found in the asymptomatic propositus' mother and grandmother, suggesting the diagnosis of autosomal dominant polycystic kidney disease (ADPKD). The renal ultrasonograms showed cortical cysts with normal or decreased-sized kidneys. Renal function was normal. Seven available members of the family were genotyped for flanking DNA markers tightly linked to the PKD1 gene on chromosome 16p, and for a polymorphism close to a second putative disease gene (PKD2) on chromosome 2. The genetic linkage approach allowed us to detect with a high degree of accuracy the ADPKD1 at risk chromosome in the three patients, as well as in a 28-year-old unaffected female. This report illustrates the feasibility and the usefulness of recent molecular genetic strategies for diagnostic purposes in ADPKD, especially when clinical and radiological data are atypical. Furthermore, it also confirms that early or very early onset forms of the disease are not uncommon, and should be considered in the differential diagnosis of childhood cystic disease.

Spontaneous vertebral artery dissection as a complication of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) may be associated with a variety of cardiovascular complications, including intracranial saccular aneurysms. In ADPKD, intracranial saccular aneurysms tend to rupture more frequently and earlier than the sporadic variety with a tendency to cluster in families. In contrast, dissecting intracranial aneurysms are rarely associated with either intracranial saccular aneurysms or ADPKD. We describe an ADPKD-1 patient whose course was complicated by a spontaneous dissection of a vertebral artery aneurysm. This particular patient had previously experienced three episodes of ascending aortic dissection with cystic medial necrosis. Intracranial vascular and aneurysmal dissection may occur in select ADPKD patients with familial clusters.

Effect of sodium chloride, enalapril, and losartan on the development of polycystic kidney disease in Han:SPRD rats

We found that the administration of an angiotensin I-converting enzyme inhibitor and sodium chloride loading lessen the development of renal cystic disease induced by 2-amino-4-5-diphenylthiazole in rats. To determine whether similar effects could be observed in an autosomal dominant model of polycystic kidney disease, heterozygous cystic (Cy/+) and homozygous normal (+/+) Han:SPRD rats were divided into experimental groups at 3 weeks of age. The first study included four groups receiving enalapril (50 mg/L), losartan (400 mg/L), hydralazine (80 mg/L), or no drug in their drinking water. The second study included four groups fed a sodium-deficient diet or the same diet supplemented with 0.25%, 0.6%, or 3.3% sodium chloride. The Cy/+ rats receiving enalapril had lower kidney weights and histologic scores than those in the control group, and lower kidney weights, plasma creatinines, and histologic scores than those in the hydralazine group. The Cy/+ rats receiving losartan had lower plasma creatinines and histologic scores than those in the control and hydralazine treatment groups. A sodium-deficient diet markedly blunted the growth of the animals and the development of cystic disease. Increases in the sodium content of the diet in the other three groups were accompanied by higher relative kidney weights and histology scores, while the levels of plasma creatinine were not significantly different. Regression of the cystic disease was observed between 3 and 4 months of age. These results indicate that the development of autosomal dominant polycystic kidney disease in the rat can be modulated by pharmacologic and nutritional factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurovascular manifestations of heritable connective tissue disorders. A review

BACKGROUND

Heritable disorders of connective tissue are recognized in a small minority of patients with neurovascular diseases. In this report, we review the neurovascular manifestations of four heritable connective tissue disorders: Ehlers-Danlos syndrome, Marfan's syndrome, osteogenesis imperfecta, and pseudoxanthoma elasticum, as well as two other systemic disorders with potential vascular manifestations: neurofibromatosis and polycystic kidney disease.

SUMMARY OF REVIEW

Typical neurovascular complications of Ehlers-Danlos syndrome are carotid-cavernous fistulae, intracranial aneurysms, and cervical artery dissections. Arterial dissections and intracranial aneurysms cause the majority of neurovascular symptoms in Marfan's syndrome. Neurovascular disease is uncommon in osteogenesis imperfecta, although carotid-cavernous fistulae and vertebral artery dissections have been reported. Neurovascular disease in pseudoxanthoma elasticum is characterized by intracranial aneurysms and cerebral ischemia caused by premature arterial occlusive disease. Intracranial occlusive arterial disease is the most common neurovascular manifestation of neurofibromatosis, followed by cervical arteriovenous fistulae and aneurysms and intracranial aneurysms. Intracranial aneurysms are the hallmark of polycystic kidney disease.

CONCLUSIONS

Recognition of an underlying generalized connective tissue disorder may be of considerable importance, although marked phenotypic heterogeneity often complicates the diagnosis of these disorders. Conversely, the association of certain neurovascular anomalies with generalized connective tissue disorders and recognition of their basic molecular defect may offer clues to the etiology and pathogenesis of these neurovascular diseases in general.