Histogenesis of the renal cysts in adult (autosomal dominant) polycystic kidney disease: a histochemical study

We studied the kidneys from ten patients with adult (autosomal dominant) polycystic kidney disease (APKD) stained with lectins specific for different segments of the nephron on 20 cysts from each case (ranging in size from 0.1 to 1.3 cm in nine cases and from 1.5 to 6 cm in one case). The epithelium of all cysts with positive reactivity (Arachis hypogaea and epithelial membrane antigen) was of collecting duct origin. Many cysts remained unstained. Cysts of proximal tubule origin could not be identified using the specific lectin Lotus tetragonolobus. Focal epithelial hyperplasia appeared in the collecting duct cysts. Cysts surrounded by smooth muscle were frequent and considered to be of collecting duct origin. One case had glomerular cysts. We conclude that the cysts of APKD are principally of collecting duct origin.     

Autosomal dominant polycystic liver disease: a second family

An autosomal dominant pattern of transmission has been established for polycystic kidney disease. The degree of cystic involvement of other organs has been variable. The genetic pattern of transmission of polycystic liver disease independent of cystic kidney disease has never been established. We present a second family with polycystic liver disease without kidney disease. The lack of renal cysts is unlikely to be due to variable expressivity and penetrance of the gene for polycystic kidney disease. The liver cysts may be of late onset since none of the proband's four children demonstrate cysts. Alternatively, none of these four individuals may have received the gene for polycystic liver disease from their affected mother. The family described supports an autosomal dominant pattern of inheritance for polycystic liver disease.     

Recurrence of orbital cysts in the branchio-oculo-facial syndrome.

Two sibs with the branchio-oculo-facial syndrome are reported. They both have orbital haemangiomatous cysts, which is a previously unreported feature. Both parents are clinically normal and unrelated. This disorder has been reported showing autosomal dominant transmission so this family could represent either an autosomal recessive form or germline mosaicism for the dominant gene.     

The liver in autosomal dominant polycystic kidney disease. Implications for pathogenesis

A histomorphometric and clinico-pathologic analysis of 26 autopsy cases of autosomal dominant polycystic kidney disease (ADPKD) showed that (1) the density of biliary microhamartomas (BMHs) and the stage of polycystic liver disease were strongly correlated, and (2) both were positively correlated with the stage of renal dysfunction and age at autopsy. Using multiple linear regression analysis, only the stage of renal dysfunction was significantly predictive of the density of BMHs, but both variables were simultaneously predictive for the stage of polycystic liver disease. On serial sections, 41.4% of cysts were connected to BMHs and 81.0% of BMHs to portal tracts. Bile-like material was found in 10.7% of BMHs. Flat or polypoid hyperplasia of the epithelium was observed in 2.7% of cysts. These results support the long-maintained view that hepatic cysts in ADPKD result from cystic dilatation of BMHs. They indicate, however, that the number of BMHs increases during life. These observations are consistent with the hypothesis that hepatic and renal cysts in ADPKD have similar pathogeneses, that BMHs and hepatic cysts result from hyperplasia of the bile duct epithelium, and that as they grow, the hepatic cysts become disconnected from the biliary ducts from which they are derived.     

Renal cysts in premature children: occurrence in a family with polycystic kidney disease

Discrete but typical renal lesions, probably representing the first stage of familial adult-type polycystic kidney disease, were found in two premature still-born daughters of a woman whose family had many cases of this autosomal dominant disease. Apparently, enough cysts were present to form polycystic kidneys of adult size solely by cyst dilation, without additional cyst formation.     

Tight junction composition is altered in the epithelium of polycystic kidneys

Kidney cysts in autosomal dominant polycystic kidney disease (ADPKD) undergo progressive enlargement together with luminal fluid secretion. This involves active, uphill transcellular Cl(-) transport which drives passive Na(+) and water secretion. Implicit in this mechanism is the assumption that the paracellular permeability of the cyst epithelium to Cl(-) must be very low. Claudins are tight junction (TJ) transmembrane proteins that determine the ion selectivity of paracellular barriers. The aim of this study was to determine the expression and localization of claudins within renal cysts in a mouse hypomorphic model of ADPKD and in human patients. We found that the majority of cysts were of collecting duct origin. Claudins normally expressed in collecting duct (3, 4, 7, 8, and 10) were found in small cysts. However, only claudin-7 persisted at substantive levels in the dedifferentiated epithelium of large, presumably late-stage cysts, where it was localized both at the TJ and basolaterally. The constitutively expressed TJ proteins, ZO-1 and occludin, were also abundantly expressed and correctly localized, suggesting that the basic infrastructure of the TJ is preserved. A previous study suggested that claudin-7 may function as a paracellular Cl(-) barrier. We postulate that the role of claudin-7 in ADPKD is to seal the paracellular route in Cl(-)-secreting cyst epithelium, preventing backleak of Cl(-), and that it thereby plays a permissive role in fluid secretion and cyst growth.     

Familial colloid cysts of the third ventricle

A father and daughter with colloid cysts of the third ventricle are described. The nine previously reported examples of familial occurrence are reviewed, and the conclusion is reached that inheritance is likely autosomal dominant. The proportion of all cases which are genetic is not known. A plea is made for routine detailed and thorough family histories on all patients with such cysts and a high index of suspicion for non-specific symptoms in relatives such as headaches, migraine, depression, anxiety, nausea and vomiting.     

Genetic and clinical studies in autosomal dominant polycystic kidney disease type 1 (ADPKD1).

Thirteen Spanish families with autosomal dominant polycystic kidney disease were studied. In one family the disease did not segregate with polymorphic markers around the PKD1 locus. All subjects over the age of 30 years carrying a mutation at the PKD1 locus showed renal ultrasonographic cysts, but 40% of carriers of the PKD1 mutation younger than 30 years did not have renal cysts. Hypertension was found to be more frequent in those with renal cysts. Recombinants between 16p polymorphic loci and the PKD1 locus are described.     

Familial cancer or cancer family syndrome. Report on a cancer family and consideration of genetic mechanisms

We present a family with an unusually high incidence of cancer in four generations. Complete information could be obtained for the first three generations with 73 persons. Tumor incidence was 2/8 in the first generation, 14/22 in the second, and 11/44 in the third generation. A formal analysis, however, according to the four criteria of cancer family syndrome: increased frequency of adenocarcinomas of multiple anatomical sites, multiple primary malignant neoplasms, early age of onset, and autosomal dominant mode of inheritance, revealed that in this family multiple primaries are virtually absent and that tumors do not occur at a particularly early age. We therefore consider this family shows that familial clustering of tumors may follow an autosomal dominant pattern of inheritance even when the strict criteria of cancer family syndrome are not fulfilled. We conclude that the phenomenon of cancer families is not confined to one or two distinct clinical types.     

Epithelial cysts of the neuraxis: presentation of three cases and a review of the origins and classification

Benign, epithelial-lined cysts of the neuraxis may be asymptomatic or may behave as space-occupying lesions. Presentation of three such cysts, including an intramedullary epidermoid cyst, a lumbosacral subcutaneous enteric cyst that has an epithelium resembling ependyma, and a hypophyseal duct cyst, illustrates typical problems encountered. Review of their histogenesis and possible embryogenesis indicates that intracranial ependymal cysts and cysts of the sella turcica are not normally associated with other anomalies and frequently occur after middle age, whereas dermal and enteric cysts occur within the first two decades and are commonly associated with vertebral anomalies and other dysraphic syndromes. Enteric cysts may have a variable histologic appearance, including one resembling ependymal cysts. Recognition of the latter is important because of a possible associated dysraphic syndrome and the presence of an extraneuraxial component with the former but not the latter.     

Multifocal renal cell carcinoma in sibs from a chromosome 9 linked (TSC1) tuberous sclerosis family.

Multifocal renal cell carcinomas (RCCs), together with angiomyolipomas (AMLs) and renal cysts, were identified in early adult life in two sisters with tuberous sclerosis (TSC). They were members of a multigenerational tuberous sclerosis family showing strong evidence for a mutant TSC causing gene on chromosome 9 (TSC1). Previous reports of multifocal RCC in young patients with TSC suggest that constitutional mutations at the TSC loci may predispose to RCC. In the rat a germline mutation affecting the TSC2 gene is associated with transmission of multifocal RCC as an autosomal dominant trait. However, the cases reported here are the first to suggest a similar role for the TSC1 gene in renal cell carcinogenesis.     

Galectin-3 associates with the primary cilium and modulates cyst growth in congenital polycystic kidney disease

Several lines of evidence implicate the beta-galactoside-binding lectin galectin-3 in development and pathological processes in renal collecting ducts: galectin-3 is expressed in the ureteric bud/collecting duct lineage during nephrogenesis, modulates collecting duct growth/differentiation in vitro, and is expressed in human autosomal recessive polycystic kidney disease in cyst epithelia, almost all of which arise from collecting ducts. Moreover, exogenous galectin-3 restricts growth of cysts generated by Madin-Darby canine kidney collecting duct-derived cells in three-dimensional culture in collagen. Using the cpk mouse model of recessively inherited polycystic kidney disease, we observed widespread galectin-3 mRNA and protein in cyst epithelia. Exogenous galectin-3 reduced cyst formation in suspension culture, and mice-null mutant for galectin-3 had more extensive renal cysts in vivo. Galectin-3 was also detected for the first time in the centrosome/primary cilium, which has been implicated in diverse polycystic kidney disease. Cilia structure/number appeared normal in galectin-3-null mutants. Finally, paclitaxel, a therapy that retards polycystic kidney disease in cpk mice, increased extracellular galectin-3, in which the lectin could potentially interact with cilia. These data raise the possibility that galectin-3 may act as a natural brake on cystogenesis in cpk mice, perhaps via ciliary roles.     

Spinal extradural arachnoid cysts associated with distichiasis and lymphedema

Spinal extradural arachnoid cysts (SEDAC) are lesions communicating to the subarachnoid space of the spinal canal via a dural defect. SEDAC occupies intraspinal space and sometimes causes neurological disturbances. Although most reported cases are sporadic, several familial cases have been described, suggesting a genetic etiology. Here we report on a family with SEDAC inherited in an autosomal dominant mode. Detailed study showed that the family has the lymphedema-distichiasis syndrome. Among family members examined, a total of ten in two generations manifested all or some of the following features: SEDAC, distichiasis and lymphedema. Seven had spinal cysts, four had both SEDAC and distichiasis, and one had SEDAC distichiasis and lymphedema; three did not have SEDAC. These findings, together with rarity of both distichiasis and lymphedema in the general population, support that all of the ten members were affected with one clinical entity, the lymphedema-distichiasis syndrome. The distribution of features illustrates the variable expressivity of clinical manifestations. Although FOXC2 mutation analysis was not performed in our family, it is likely that SEDAC is a component manifestation of lymphedema-distichiasis syndrome and more consistent in our family than those reported.     

Renal failure in a patient with autosomal dominant polycystic kidney disease and coexisting dermato-polymyositis: first report in the literature

Autosomal dominant polycystic kidney disease is a multisystem disorder characterized by multiple, bilateral renal cysts and is also associated with cysts in other organs, such as the liver, pancreas, and arachnoid membranes. Dermatomyositis is a disease which mainly involves the skin and muscles, although occasionally other organs are affected. In this report, a 56-year-old male patient with a four-year history of autosomal dominant polycystic kidney disease was presented. Renal failure was exacerbated by a coexisting dermato-polymyositis. Prednisone treatment with hemodialysis improved the situation. This is the first report renal failure in a patient with autosomal dominant polycystic kidney disease and dermato-polymyositis.     

Recurrence of neonatal haemochromatosis in half sibs born of unaffected mothers.

We report two families in which neonatal haemochromatosis was observed in half sibs. In the first family, two successive girls were born of different fathers. In the second family, an affected brother and sister were followed by an affected half brother born after donor insemination. These observations, as well as a previous abstract describing two affected half sisters, revive the debate over the inheritance of neonatal haemochromatosis. Incomplete penetrance or gonadal mosaicism for a dominant disorder, a maternal "environmental factor", or mitochondrial defect may be more suitable explanations than autosomal recessive inheritance in this condition. Alternative modes of fertilisation, such as donor insemination or in vitro fertilisation with donor eggs, should be considered with caution.     

Conductive deafness, symphalangism, and facial abnormalities: the WL syndrome in a Japanese family

We report on a family in which four relatives were affected with an autosomal dominant syndrome of unusual facial appearance, nasal abnormality, conductive deafness, pectus carinatum, and symphalangism. This appears to be only the second report of the WL symphalangism syndrome of Herrmann and the first studied in a Japanese family.     

Is cascade testing a sensible method of screening a population for autosomal recessive disorders?

Our aim was to evaluate "cascade testing" as a method of screening a population for autosomal recessive disorders. We used computer simulations to estimate screening performance according to carrier frequency, whether testing would extend to siblings, first or second cousins of identified carriers and family size. Cascade testing in populations with the distribution of family size current in England and Wales would require locating and testing a small proportion of the population as expected, but would detect few cases. For cystic fibrosis (carrier frequency of 4%), testing all siblings and first cousins of all identified carriers would require locating and testing only 1.9% of the whole population, but would detect only 15% of all new cases. Similarly for congenital adrenal hyperplasia (carrier frequency of 1%), testing all siblings and first cousins of all identified carriers would require locating and testing only 0.1% of the whole population, but would detect only 3.1% of all new cases. The detection rate increases with increasing carrier frequency, family size and extending the testing to second cousins of identified carriers, but at the cost of greater increases in the proportion of the population located and tested. The performance of cascade testing is too poor to justify its introduction into practice as a screening test for any autosomal recessive disorder.     

Congenital biliary dilatation in autosomal dominant adult polycystic disease of the liver and kidneys

Specimens of autopsied livers and biliary tracts of three patients with autosomal dominant adult polycystic disease of the liver and kidneys were examined morphologically with adjunct postmortem cholangiography. The cholangiograms revealed nonobstructive diffuse dilatation of intrahepatic bile ducts in all cases. Macroscopic examination confirmed the nonobstructive ductal dilatation and also showed a number of cysts in all cases. Microscopically, the dilated bile duct walls were composed of fibrous walls and were free of other pathologic changes, suggesting that the biliary dilatation was congenital in origin. Small microscopic bile ducts, however, were not dilated and were free of ductal plate malformation. In addition, Meyenburg's complexes and liver cysts not communicating with the biliary tract lumen were seen. It was suggested that adult polycystic disease, Meyenburg's complexes, and congenital intrahepatic biliary dilatation could coexist in some patients.     

The genetic landscape of polycystic kidney disease in Ireland

Polycystic kidney diseases (PKDs) comprise the most common Mendelian forms of renal disease. It is characterised by the development of fluid-filled renal cysts, causing progressive loss of kidney function, culminating in the need for renal replacement therapy or kidney transplant. Ireland represents a valuable region for the genetic study of PKD, as family sizes are traditionally large and the population relatively homogenous. Studying a cohort of 169 patients, we describe the genetic landscape of PKD in Ireland for the first time, compare the clinical features of patients with and without a molecular diagnosis and correlate disease severity with autosomal dominant pathogenic variant type. Using a combination of molecular genetic tools, including targeted next-generation sequencing, we report diagnostic rates of 71–83% in Irish PKD patients, depending on which variant classification guidelines are used (ACMG or Mayo clinic respectively). We have catalogued a spectrum of Irish autosomal dominant PKD pathogenic variants including 36 novel variants. We illustrate how apparently unrelated individuals carrying the same autosomal dominant pathogenic variant are highly likely to have inherited that variant from a common ancestor. We highlight issues surrounding the implementation of the ACMG guidelines for variant pathogenicity interpretation in PKD, which have important implications for clinical genetics.Subject terms: Polycystic kidney disease, Disease genetics, Next-generation sequencing, Genetics research, Genetic testing     

Coordinate Expression of the Autosomal Dominant Polycystic Kidney Disease Proteins, Polycystin-2 And Polycystin-1, in Normal and Cystic Tissue

A second gene for autosomal dominant polycystic kidney disease (ADPKD), PKD2, has been recently identified. Using antisera raised to the human PKD2 protein, polycystin-2, we describe for the first time its distribution in human fetal tissues, as well as its expression in adult kidney and polycystic PKD2 tissues. Its expression pattern is correlated with that of the PKD1 protein, polycystin-1. In normal kidney, expression of polycystin-2 strikingly parallels that of polycystin-1, with prominent expression by maturing proximal and distal tubules during development, but with a more pronounced distal pattern in adult life. In nonrenal tissues expression of both polycystin molecules is identical and especially notable in the developing epithelial structures of the pancreas, liver, lung, bowel, brain, reproductive organs, placenta, and thymus. Of interest, nonepithelial cell types such as vascular smooth muscle, skeletal muscle, myocardial cells, and neurons also express both proteins. In PKD2 cystic kidney and liver, we find polycystin-2 expression in the majority of cysts, although a significant minority are negative, a pattern mirrored by the PKD1 protein. The continued expression of polycystin-2 in PKD2 cysts is similar to that seen by polycystin-1 in PKD1 cysts, but contrasts with the reported absence of polycystin-2 expression in the renal cysts of Pkd2+/- mice. These results suggest that if a two-hit mechanism is required for cyst formation in PKD2 there is a high rate of somatic missense mutation. The coordinate presence or loss of both polycystin molecules in the same cysts supports previous experimental evidence that heterotypic interactions may stabilize these proteins.