Benign and malignant tumors in multiple organ systems

Transcription

1 VICKI COUCH, MS; NORALANE M. LINDOR, MD; PAMELA S. KARNES, MD; AND VIRGINIA V. MICHELS, MD An autosomal dominant tumor predisposition syndrome, von Hippel-Lindau disease (VHL) is characterized by the presence of benign and malignant tumors. Hallmark lesions include retinal angiomas, hemangioblastomas of the cerebellum and spinal cord, and renal cell carcinomas. Affected persons may also have angiomatous or cystic lesions of the kidneys, pancreas, and epididymis, as well as adrenal pheochromocytomas. In this article, we discuss the clinical features and diagnostic criteria for this clinically underdiagnosed condition. An update on recent findings regarding the molecular genetics of VHL is provided, including a discussion of the evolving understanding of geno- type-phenotype correlations. Understanding the molecular and functional aspects of this condition will lead to the development of strategies for the management and treatment of inherited and sporadic VHL-associated tumors. Mayo Clin Proc. 2000;75: CNS =central nervous system; CT =computed tomography; MRI = magnetic resonance imaging; mrna = messenger RNA; pvhl =VHL protein; RCC =renal cell carcinoma; VEGF = vascular endothelial growth factor; VHL = von Hippel-Lindau disease Benign and malignant tumors in multiple organ systems are the characteristic findings in patients with von Hippel-Lindau disease (VHL), a hereditary multisystemic disorder. Hallmark features of the condition include development of retinal angiomas, hemangioblastomas of the cerebellum and spinal cord, and renal cell carcinomas (RCCs). Additionally, this condition can cause angiomatous or cystic lesions in the kidneys, pancreas, and epididymis as well as adrenal pheochromocytomas. I Since the mid-1800s, ophthalmologists have reported retinal angiomas associated with blindness and occasionally with similar cerebellar lesions.' In 1904, German ophthalmologist Eugen von Hippel first recognized the hereditary component of retinal angiomas.' In 1927, Arvid Lindau, a Swedish pathologist, was the first to report a connection between retinal angiomas and hemangiomas of the cerebellum." Subsequently, numerous clinical reports have described families with retinal angiomas, central nervous system (CNS) hemangioblastomas, renal tumors and cysts, epididymal cystadenomas, pancreatic cysts and tumors, and pheochromocytomas, confirming the association of these Iesions.? However, it was not until 1964 that Melman and Rosen' coined the term von Hippel-Lindau disease in their classic review of the subject. von Hippel-Lindau disease is seen in all ethnic groups, and both sexes are affected equally. Epidemiological stud- From the Department of Medical Genetics, Mayo Clinic Rochester, Rochester, Minn. Address reprint requests and correspondence to Vicki Couch, MS, Department of Medical Genetics, Mayo Clinic Rochester, 200 First St SW, Rochester, MN Mayo Clin Proc. 2000;75: ies suggest that the birth incidence in eastern England is I in 36,000,6 and the prevalence in southwestern Germany is 1 in 39,000 persons.' Penetrance is estimated at 80% to 90% by the time a person is 65 years old, and expression is highly variable." The age at diagnosis ranges from infancy to the seventh decade of life or later, depending on the expression of the condition within the family and whether and which type of asymptomatic lesions are sought. Although VHL is considered rare, the condition is likely underdiagnosed." The goal of this review is to familiarize the practicing physician with this important, yet underrecognized, syndrome that predisposes to cancer. CLINICAL FEATURES There are several characteristic features of VHL but no single unique pathognomonic finding. Thus, multidisciplinary involvement in the diagnosis and management of this condition is crucial, and many investigators have stressed the importance of interdisciplinary exchange of information.p-'? CNS Hemangioblastomas Central nervous system hemangioblastomas are most frequently found in the cerebellum and then the spine and the brain stem, I I Supratentorial hemangioblastomas can occur, although they are rare. Central nervous system involvement is reported in 21% to 72% of VHL patienrs.v" In VHL, the tumors are often multiple, and the mean age of VHL patients at diagnosis of cerebellar hemangioblastomas is considerably younger than that of patients with sporadic cases. The primary age range of VHL pa Mayo Foundation/or Medical Education and Research

2 266 tients who present with CNS lesions is 25 to 40 years, although CNS lesions can occur in children.v"-" The hemangioblastomas seen in VHL are benign, but they may produce symptoms depending on their size, site, and number. Symptoms are due to local disruption of neurologic function or increased intracranial pressure, sometimes compounded by hydrocephalus. Spinal cord lesions may cause syringomyelia." Surgical resection of CNS hemangioblastomas often provides excellent results. However, the development of multiple tumors is still a major problem, and CNS involvement is an important cause of morbidity and mortality in patients with VHL. 14,15 Symptoms of CNS hemangioblastomas can include headache, nausea, vertigo, and broad-based gait. Signs such as papilledema, ataxia, slurred speech, and nystagmus may occur." Detection of CNS hemangioblastomas has improved substantially with the use of modem imaging techniques and preventive screening of VHL patients to identify presymptomatic or asymptomatic tumors. The current preferred method for detection of CNS lesions in VHL is gadolinium-enhanced magnetic resonance imaging (MRI), for both intracranial and intraspinal tumors.l-" More studies are needed to confirm whether presymptomatic CNS screening for and treatment of identified lesions in patients who have VHL or are at risk for VHL actually improves quality of life or extends survival. Retinal Angiomas Retinal angiomas (hemangioblastomas) are present in more than one half of all patients with VHL. 9,18,19 These benign tumors are often multiple, bilateral, and recurrent. If untreated, they may cause retinal detachment and hemorrhage, leading to blindness. Most angiomas are found in the second and third decades of life, with a mean age at diagnosis of 25 years.v" However, age at onset is variable; these tumors can be found in infants, or they may not be present until the eighth decade of life or later." Often, there are no clinical symptoms until serious damage occurs due to hemorrhage, retinal detachment, or other complications. Detection of these lesions is by ophthalmoscopic examination, with the classic finding being a reddish spherical tumor of variable size with a dilated feeding artery and a draining vein. 22,23 Microangiomas with no dilated or tortuous feeder vessels precede the tumors. Most small lesions are peripheral and difficult to detect. 10 Regular ophthalmologic examinations, often including tonometry, fluorescein angioscopy, and indirect ophthalmoscopy, are an essential component of the preventive screening that should be performed for all patients with VHL. IO, 13,2 1 Treatment of small lesions is by laser coagulation and cryotherapy, usually with few complications." Thus far, the pathogenesis of retinal detachment in VHL is poorly understood. It often occurs with no warning symptoms, and there may be no identifiable precipitating factor. Treatment of detachment is difficult and often unsuccessful. 10 This is a compelling reason for regular ophthalmologic screening and early intervention for retinal lesions in VHL. Many clinicians recommend initiation of annual ophthalmologic screening at an early age (6 years or younger) to ensure that vision can be preserved.p:" Renal Lesions The renal lesions in VHL include both cysts and carcinomas.":" Renal cysts are present in 50% to 70% of patients, and, while they are frequently bilateral and multiple, they rarely cause pronounced renal impairment.v-" Occasionally, innumerable cysts are present, as occurs in autosomal dominant polycystic kidney disease." Unlike the sequelae in autosomal dominant polycystic kidney disease, multiple cysts in VHL infrequently lead to chronic renal decompensation or renal hypertension." The predominant histological finding of an RCC in patients with VHL is a clear cell carcinoma.p'-'? The lifetime risk for RCC is greater than 70%, and RCC causes death in 15% to 50% of VHL patients."?" When an RCC is identified as a result of symptoms, 30% to 50% of VHL patients with renal lesions already have metastases to the lymph nodes, liver, lungs, or bones.>" These metastatic lesions respond poorly to chemotherapy and radiation. 10 Thus, the strategy for managing patients with VHL or those at risk for VHL is careful annual surveillance with computed tomography (CT), ultrasonography, or both. If only asymptomatic cysts are identified, continued surveillance is sufficient. When solid lesions are detected, treatment is parenchymal-sparing surgery when possible.p'" Because the lesions are often bilateral, partial nephrectomy or tumor enucleation, when possible, may avoid or delay the need for dialysis or transplantation. Microscopically, kidneys from patients with VHL may contain numerous small neoplasms, and the development of primary tumors is almost inevitable." Patients must be informed of the need for ongoing surveillance and the likelihood of repeated renal surgery. The goal of renal surgery in patients with VHL is to prolong renal function while decreasing the risk of metastasis. Pheochromocytomas Approximately 20% of all pheochromocytomas are due to VHL. 37 The pheochromocytomas seen in VHL differ from those in sporadic cases since they occur in younger patients and are often bilateral, multiple, and extra-adrenal. Metastasis is infrequent. 32,38,39 A pheochromocytoma may be the only symptom of VHL in an affected person. 37 Pheochromocytomas are seen in 7% to 20% of families For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,

3 with VHL.9,19 There is dramatic clustering of pheochromocytomas in a subset of families with VHL (as is discussed in the section on diagnostic criteria). However, it is still unclear whether the correlation between specific VHL genotypes and particular phenotypic expression of the disorder will be absolute. It may be tempting to use details of a patient's genotype to determine whether to pursue screening for pheochromocytomas (or possibly for other manifestations of VHL), but this approach is premature. For example, evidence shows that modifier genes may influence the expression of the phenotype of VHL. 14 Additional research is needed for a complete definition of the specificity and sensitivity of the relationship between particular VHL mutations and the predicted disease spectrum before such genotype-specific screening strategies can be endorsed. Thus, while a family history of pheochromocytomas in affected relatives is clearly an indication for careful surveillance," all persons diagnosed with or at risk for VHL should be screened regularly for a pheochromocytoma. Pheochromocytomas among patients with VHL may cause intermittent or sustained hypertension, episodic sweating, palpitations, and headaches. Pheochromocytomas are diagnosed by biochemical tests, which demonstrate elevated urine levels of catecholamines (epinephrine, norepinephrine, and metanephrine), in combination with imaging studies (ultrasonography, CT, or MRI).40,41 Often, pheochromocytomas in VHL remain asymptomatic, and findings on biochemical tests and MRI may be unremarkable." The behavior of pheochromocytomas in VHL is unpredictable, and previously inactive pheochromocytomas may suddenly become life threatening. This situation can be especially risky if an unsuspected pheochromocytoma is present in a patient with VHL who has a cerebellar hemangioblastoma, is undergoing surgery for another VHL-associated lesion, or is pregnant.":" Screening for pheochromocytomas before surgery consists of 24-hour urine metanephrine and catecholamine determinations. If the patient is normotensive and asymptomatic, results obtained within the past 6 months are acceptable; however, if the patient is hypertensive or symptomatic, current studies are necessary. Symptomatic pheochromocytomas must be removed surgically. When there are bilateral lesions, adrenal-sparing surgery may be considered to preserve some functioning adrenal tissue." As with nephron-sparing surgery in patients with VHL, this necessitates ongoing surveillance for recurrent pheochromocytomas. If pheochromocytomas must be removed, it is important to attempt to localize extra-adrenal pheochromocytomas that may be present and to recognize the potential for life-threatening complications during surgery because manipulation can cause a 267 sudden elevation in circulating catecholamines, leading to hypertension and arrhythmia during surgery." Pancreatic Lesions Pancreatic lesions are common in VHL and are most often limited to cysts.25,44 These lesions are diagnosed in patients at the mean age of 41 years, although they can be diagnosed from the second through the sixth decade of Iife." The cysts are often multiple and are present throughout the body of the pancreas. They are frequently asymptomatic, but complications can occur because of space-occupying effects. If biliary obstruction occurs, it is managed by placement of biliary stents. Pancreatic exocrine insufficiency may develop and is managed by enzyme replacement. 13 Imaging techniques such as CT or MRI may provide more accurate detection of small lesions and solid lesions than ultrasound scanning.w" but over a lifetime a combination of imaging techniques is suggested to balance cost and radiation exposure. Pancreatic islet cell tumors (which can secrete insulin) can occur in VHL. This process is apparently independent of the pancreatic cyst formation, and the tumors are of neural origin." Like the renal, CNS, and retinal lesions in VHL, pancreatic islet cell tumors are substantially vascular. Most of these lesions grow slowly and are asymptomatic, although they can be malignant, Computed tomography or MRI is used to diagnose islet cell tumors, and lesions that are growing are excised surgically. Epididymal Lesions Epididymal lesions are found in 10% to 60% of male patients with VHL.2,16 Papillary cystadenomas of the epididymis may be unilateral or bilateral. These lesions are benign and, if bilateral, may present as infertility." An analogous lesion may occur in women with VHL, presenting as papillary cystadenoma of the broad ligament." Endolymphatic Sac Tumors Endolymphatic sac tumors were only recently recognized as a manifestation of VHL.50 An estimated 10% of VHL patients have these slow-growing, low-grade papillary adenocarcinomas. These tumors are frequently bilateral and can invade locally, an outcome associated with hearing loss. Patients with VHL who experience symptoms such as hearing loss, vertigo, or tinnitus should undergo CT or MRI of the internal auditory canal. Whether surgical intervention will help preserve hearing is still unknown." DIAGNOSTIC CRITERIA Minimal diagnostic criteria for patients with a known family history of VHL include the presence of a single retinal or cerebellar hemangioblastoma, RCC, or pheochromo- For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,

4 268 cytoma.' Multiple pancreatic cysts may indicate that an at-risk person inherited the mutation since these lesions are otherwise uncommon. However, because renal and epididymal cysts occur with some frequency in the general population, the presence of these lesions may not be reliable evidence that an at-risk person carries a VHL mutation." The number of renal cysts and age at detection must be considered because such cysts are extremely uncommon in children and young adults, especially if they are multiple. In an isolated case, the clinical diagnosis of VHL can be made in a person who has 2 or more retinal or CNS hemangioblastomas or a single hemangioblastoma and a characteristic visceral tumor." De novo mutations tend to be underrecognized compared with mutations in a familial setting. A diagnosis of VHL should be considered in any patient with a retinal or CNS hemangioblastoma, especially if onset is at an early age and there are familial, early-onset, or bilateral clear cell RCC; familial or bilateral pheochromocytoma; and bilateral endolymphatic sac tumors." There is a fairly clear distinction between VHL families with greater or lesser likelihood of developing pheochromocytomas (as discussed further in the section on genotype-phenotype correlations). Investigators have proposed that VHL without pheochromocytoma be classified as type 1 while that with pheochromocytoma be classified as type 2.52 Type 2 has been further divided into type 2A, VHL with pheochromocytomas but without RCC, and type 2B, VHL with pheochromocytomas and RCC. 53 Mayo Clin Proc, March 2000, Vol 75 ing recommendations, even in the absence of a known family history of the disorder. Such persons may have VHL due to a new mutation not previously present in their family, and each of their offspring would have a 50% risk of inheriting the mutation. Alternatively, other relatives of a person with an apparently sporadic case of VHL may also carry the VHL gene mutation and not yet manifest clinically recognized symptoms. In this situation, relatives such as parents, siblings, and children would be at risk for manifestations of the disorder. Mutation analysis can be offered to family members of a person who appears to have a sporadic case of VHL, and for whom a mutation in the gene for VHL has been identified, to determine whether they are currently asymptomatic gene carriers who would benefit from VHL screening recommendations. In discussing the option of predictive mutation analysis for at-risk persons when a mutation has been identified in an affected family member, reviewing potential risks and benefits of obtaining such information is important. In other inherited cancer predisposition conditions, a concern is that predictive mutation testing may result in possible employment or insurance discrimination for a person who is found to carry a predisposing mutation. This concern may be most germane in the setting of cancer predisposition syndromes for which there is no evidence of benefit from early screening of currently asymptomatic gene carriers. However, in VHL, there is a direct benefit from appropriateearly screening, beginning in childhood.v" MOLECULAR GENETICS Identification and Localization of the VHL Gene CLINICAL GENETIC TESTING Genetic testing (which is described subsequently in more detail) can also be used to determine whether a person carries a pathological mutation in the VHL gene. Deleterious mutations in the VHL gene can be identified in 80% or more of families with VHL. 54 In a VHL family in which a mutation has previously been identified in an affected person, at-risk relatives can be tested to determine whether they carry the same mutation. With this approach, family members with a 50% risk of having inherited a mutation but found not to have the specific mutation known to be present in an affected family member can be reassured that they do not need to follow the screening recommendations, which are appropriate for those who do have the mutation; thus, they are spared the expense and inconvenience of repeated medical testing.'? In a person who has no known family history of VHL but has a personal clinical history that is suspicious for this disorder, a gene test may be able to confirm whether there is a known deleterious mutation in the gene for VHL. Clearly, such a person would benefit from full VHL screen- Evidence from clinical and molecular epidemiological data suggests that VHL is due to inactivation of a tumor suppressor gene." Tumor suppressor genes inhibit tumor cell development, and their loss or inactivation predisposes to cancer. Carriers of mutations in a tumor suppressor gene inherit a germline mutation in 1 allele of the gene, and tumors develop if a somatic mutation occurs in the homologous normal allele. 16 While the germline mutation is inherited in an autosomal dominant fashion with a 50% risk of the mutant allele being transmitted to each child, the actual mechanism of tumor development in a specific cell is recessive because tumors occur only when both copies of the tumor suppressor gene are inactivated. This "2-hit" hypothesis for the origin of cancer was proposed by Knudson" in 1971 to explain the observation that some types of cancer, such as retinoblastoma, occur in both sporadic and hereditary forms. Inherited cases of retinoblastoma tend to involve bilateral, multifocal tumors and are typically diagnosed at an earlier age than sporadic cases, in which the tumors are usually unilateral. Tumor suppressor genes have regulatory roles in cell proliferation and differentiation as For personal use, Mass reproduce only with permission from Mayo Clinic Proceedings,

5 Mayo elin Proc, March 2000, Vol7S well as other basic cellular functions and have been found to have a role in other inherited cancer syndromes, such as multiple endocrine neoplasia type I and familial adenomatous polyposis. Consistent with the idea that VHL is due to germline mutations in a tumor suppressor gene, the VHL gene was mapped to a chromosomal region, 3p25-26, that is frequently altered or deleted in sporadic RCC.56 The mapping of the VHL gene to chromosome 3, and the eventual isolation of the gene, was aided by the identification of several VHL families with germline deletions in the VHL gene." These deletions were overlapping, with the area of minimal deletion providing precise physical localization for the VHL gene. In addition, in VHL families in which it was possible to track the parental origin of the chromosome 3p sequences, the copy that was lost in the VHL-associated lesions was the one bearing the wild-type allele. 58 This demonstrates that both copies of the VHL gene were inactivated in the VHL tumors, a hallmark of tumor suppressor genes. These findings indicate that normal function of the VHL gene is necessary for control of cell growth in certain cell types. A germline mutation in I allele is the first " hit," with the second " hit" causing loss of the wildtype allele, leading to development of tumors and cancers in certain tissues. This follows Knudson 's 2-hit model of tumorigenesis as it was originally demonstrated for retinoblastoma. The VHL gene, which was identified in 1993, consists of 3 exons, encoding 213 amino acids. Exon 2 is alternatively spliced, resulting in transcribed messenger RNAs (mrnas) of 2 distinct sizes, 6 and 6.5 kilobase." VHL patients have been identified who have germline deletions of exon 2, resulting in expression of only the shorter mrna product. This suggests that the shorter transcript is not a full y functional gene product." Both of the mrnas are expressed in adult tissues, including the brain, kidneys, adrenal glands, prostate, lungs, and heart. IO 59 Because VHL-mRNA expression is not restricted to those organs affected by VHL, thus far no tissue tested for the pre sence of the mrna transcript has been negative.t">' In fetal brain, only the shorter mrna transcript is expressed, whereas in fetal kidneys, only the longer transcript is expre ssed. This is consistent with a role in normal renal tubular development and differentiation.s':" Genotype-Phenotype Correlations Germline VHL mutations have been detected in almost 500 families with VHL The mutations are extremely heterogeneous and occur throughout the coding region, except that intragenic mutations are rare in the first 50 codons. About 15% to 20 % of patients have large germline deletions, which can be detected by Southern blot 269 analysis, 27 % have missense mutations, and 27% have frameshift or nonsense mutations. By using Southern blot analysis and direct sequencing of the coding region, mutations can be identified in 80% or more of VHL families. There appears to be a strong correlation between the type of mutation and the clinical phenotype of VHL. The mutations associated with VHL type 1 (without pheochromocytoma) are deletions and protein-truncating mutations such as nonsense mutations and microdeletions-insertions in most families. In VHL type 2 (with pheochromocytoma), 96% of families have missense mutations. However, not all missense mutations are associated with a high risk of pheochromocytorna.t- " VHL Protein Product The VHL protein (pvhl) contains 213 amino acids with a primary sequence that has no important homology to other proteins." Immunostaining and biochemical fractionation studies suggest that pvhl is found primarily in the cytoplasm.p:" In an effort to understand the mechanisms by which pvhl acts as a tumor suppressor, several groups sought to identify cellular pvhl-binding proteins. i':" Two such proteins, Elongin B and C, bind to a region of pvhl that is frequently mutated in VHL families this binding prevents assembly of a transcriptional elongation complex called Elongin (SIll) by blocking binding of the B/C com plex with the catalytic subunit, Elongin A.82 Elongin (SIll) activates transcription of mrna, both by inhibiting the arrest of polymerase II at distinct sites of the DNA (called "pausing") and by controlling the release of polymerase II from the DNA. 83 Thus, competitive inhibition of Elongin A binding to Elongin B/C by pvhl acts to down-regulate the transcription rate of certain genes." Mutated forms of pvhl that are unable to associate with Elongin BIC may disturb the normal VHL tumor suppressor function by preventing regulation of transcription rates." :" The Elongin B/C-pVHL complex may act in a way unrelated to its ability to promote transcriptional elongation. VHL and Angiogenesis Angiogenesis is a striking feature of the clinical manifestations of VHL, with its characteristic cysts and wellvascularized tumors. Vascularization of tumors is induced by several stimuli, including hypoxia and polypeptide growth factors such as vascular endothelial growth factor (VEGF).84 The hypervascular nature of VHL lesions has been linked to the overproduction of VEGF by tumor cells. Vascular endothelial growth factor is normally expressed in the brain, kidneys, and other tissues, and it is substantially overexpressed in RCC and in sporadic and VHL-

6 270 von Hlppel-Lmdau Disease associated CNS hemangioblastomas.p'" The up-regulation of VEGF by hypoxia may be mediated by increased mrna stability." Cell lines lacking wild-type VHL inappropriately produce hypoxia-inducible mrnas under both hypoxic and normoxic conditions.p'?" Reintroduction of wildtype, but not mutant, pvhl into these VHL (-/-) cells reconstitutes the hypoxia-regulated expression of VEGF mrna and inhibits VEGF expression under normoxic conditions. This suggests that hypoxia initiates VEGF transcription via a VHL-mediated pathway, perhaps involving the Elongin complex or other proteins that regulate mrna stability I! SUMMARY 14. Like many other hereditary cancer syndromes, VHL is due to a germline mutation affecting a tumor suppressor gene. This potentially malignant disease may be underrecognized by physicians. Central nervous system hemangioblastoma and RCC are the most serious of the numerous characteristic lesions. When VHL is diagnosed in a patient, lifelong and close follow-up for multiple and recurrent tumors is necessary. The diagnosis of VHL also has implications for family members of the patient, potentially involving many relatives. If mutation testing of the affected patient results in an identifiable mutation, at-risk relatives can be offered the option of presymptomatic gene testing. Alternatively, if no identifiable mutation is located or if the relative prefers not to undergo mutation analysis, screening of first-degree relatives for evidence of VHL-associated tumors is recommended. Increased recognition of the need for screening in VHL has improved the prognosis for affected patients. The evolving understanding of genotype-phenotype correlations and the molecular and functional aspects of this condition will lead to the development of strategies for the management and treatment of inherited and sporadic VHLassociated tumors. 15. REFERENCES McKusick VA. Mendelian Inheritance in Man: A Catalog of Human Genes and Genetic Disorders. 12th ed. Baltimore, Md: Johns Hopkins University Press; Choyke PL, Glenn GM, Walther MM, Patronas NJ, Linehan WM, Zbar B. von Hippel-Lindau disease: genetic, clinical, and imaging features [published correction appears in Radiology. 1995; 196:582]. Radiology. 1995;194: von Hippel E. Uber eine sehr seltene Erkrankung der Netzhaut. Graefes Arch Clin Exp Ophthalmol. 1904;59: Lindau A. Zur Frage der Angiomatosis retinae und ihrer Himcomplikation. Acta Ophthalmol (Scand). 1927;4: Melmon KL, Rosen SW. Lindau's disease: review of the literature and study of a large kindred. Am J Med. 1964;36: Maher ER, Iselius L, Yates JR, et at. von Hippel-Lindau disease: a genetic study. J Med Genet. 1991;28: Neumann HP, Wiestler 00. Clustering of features of von HippelLindau syndrome: evidence for a complex genetic locus. Lancet. 1991;337: Maher ER. von Hippel-Lindau disease. Eur J Cancer. 1994; 30A: Lamiell JM, Salazar FG, Hsia YEo von Hippel-Lindau disease affecting 43 members of a single kindred. Medicine (Baltimore). 1989;68:1-29. Neumann HP, Lips CJ, Hsia YE, Zbar B. von Hippel-Lindau syndrome. Brain Pathol. 1995;5: Filling-Katz MR, Choyke PL, Oldfield E, et a1. Central nervous system involvement in von Hippel-Lindau disease. Neurology. 1991;41: Maher ER', Yates JR, Ferguson-Smith MA. Statistical analysis of the two stage mutation model in von Hippel-Lindau disease, and in sporadic cerebellar haemangioblastorna and renal cell carcinoma. J Med Genet. 1990;27: Linehan WM, Klausner RD. Renal carcinoma. In: Vogelstein B, Kinzler KW, eds. The Genetic Basis ofhuman Cancer. New York, NY: McGraw-Hill; 1998: Maher ER, Kaelin WG Jr. von Hippel-Lindau disease. Medicine (Baltimore). 1997;76: Neumann HP, Eggert HR, Scheremet R, et a1. Central nervous system lesions in von Hippel-Lindau syndrome. J Neurol Neurosurg Psychiatry. 1992;55: Karsdorp N, Elderson A, Wittebol-Post 0, et at. von Hippel-Lindau disease: new strategies in early detection and treatment. Am J Med. 1994;97: Filling-Katz MR, Choyke PL, Patronas NJ, et at. Radiologic screening for von Hippel-Lindau disease: the role of Gd-DTPA enhanced MR imaging of the CNS. J Comput Assist Tomogr. 1989; 13: Neumann HP. Basic criteria for clinical diagnosis and genetic counselling in von Hippel-Lindau syndrome. Vasa. 1987;16: Maher ER, Yates JR, Harries R, et at. Clinical features and natural history of von Hippel-Lindau disease. QJM. 1990;77: Green JS, Bowmer MI, Johnson GJ. von Hippel-Lindau disease in a Newfoundland kindred. CMAJ. 1986;134: , 146. Moore AT, Maher ER, Rosen P, Gregor Z, Bird AC. Ophthalmological screening for von Hippel-Lindau disease. Eye. 1991;5: Ridley M, Green J, Johnson G. Retinal angiomatosis: the ocular manifestations of von Hippel-Lindau disease. Can J Ophthalmol. 1986;21: Welch RB. von Hippel-Lindau disease: the recognition and treatment of early angiomatosis retinae and the use of cryosurgery as an adjunct to therapy. Trans Am Ophthalmol Soc. 1970;68: Glenn GM, Choyke PL, Zbar B, Linehan WM. von Hippel-Lindau disease: clinical review and molecular genetics. Probl Urol. 1990; 4: Horton WA, Wong V, Eldridge R. von Hippel-Lindau disease: clinical and pathological manifestations in nine families with 50 affected members. Arch Intern Med. 1976;136: Poston CD, Jaffe GS, Lubensky la, et at. Characterization of the renal pathology of a familial form of renal cell carcinoma associated with von Hippel-Lindau disease: clinical and molecular genetic implications. J Urol. 1995;153: Solomon 0, Schwartz A. Renal pathology in von Hippel-Lindau disease. Hum Pathol. 1988;19: Richard S, Chauveau 0, Chretien Y, et a1. Renal lesions and pheochromocytoma in von Hippel-Lindau disease. Adv Nephrol Necker Hosp. 1994;23:1-27. Frimodt-Moller PC, Nissen HM, Dyreborg U. Polycystic kidneys as the renal lesion in Lindau's disease. J Urol. 1981;125: Malek RS, Omess PJ, Benson RC Jr, Zincke H. Renal cell carcinoma in von Hippel-Lindau syndrome. Am J Med. 1987;82: Neumann HP. Prognosis of von Hippel-Lindau syndrome. Vasa. 1987;16:

7 Levine E, Collins DL, Horton WA, Schimke RN. CT screening of the abdomen in von Hippel-Lindau disease. AJR Am] Roentgenol. 1982;139: Pearson JC, Weiss J, Tanagho EA. A plea for conservation of kidney in renal adenocarcinoma associated with von HippelLindau disease. J Urol. 1980;124: Morgan WR, Zincke H. Progression and survival after renal-conserving surgery for renal cell carcinoma: experience in 104 patients and extended foltowup.z Urol. 1990;144: Frydenberg M, Malek RS, Zincke H. Conservative renal surgery for renal cell carcinoma in von Hippel-Lindau's disease. J Urol. 1993;149: Walther MM, Lubensky la, Venzon D, Zbar B, Linehan WM. Prevalence of microscopic lesions in grossly normal renal parenchyma from patients with von Hippel-Lindau disease, sporadic renal cell carcinoma and no renal disease: clinical implications. J Ural. 1995;154: Neumann HP, Berger DP, Sigmund G, et al. Pheochromocytomas, multiple endocrine neoplasia type 2, and von Hippel-Lindau disease [published correction appears in N Engl J Med. 1994; 331:1535). N EnglJ Med. 1993;329: Sato Y, Waziri M, Smith W, et al. Hippel-Lindau disease: MR imaging. Radiology. 1988;166: Atuk NO, McDonald T, Wood T, et al. Familial pheochromocytoma, hypercalcemia, and von Hippel-Lindau disease: a ten year study of a large family. Medicine (Baltimore). 1979;58: Reinig JW, Doppman JL, Dwyer AJ, Johnson AR, Knop RH. Adrenal masses differentiated by MR. Radiology. 1986;158:8184. van Gils AP, Falke TH, van Erkel AR, et al. MR imaging and MIBG scintigraphy of pheochromocytomas and extraadrenal functioning paragangliomas. Radiographies. 1991;11: Cryer PE. Phaeochromocytoma. Clin Endocrinol Metab. 1985;14: Hull CJ. Phaeochromocytoma: diagnosis, preoperative preparation and anaesthetic management. Br J Anaesth. 1986;58: Neumann HP, Dinkel E, Brambs H, et al. Pancreatic lesions in the von Hippel-Lindau syndrome. Gastroenterology. 1991;101: Bickler S, Wile AG, Melicharek M, Recher L. Pancreatic involvement in Hippel-Lindau disease. West] Med. 1984;140: Choyke PL, Filling-Katz MR, Shawker TH, et al. von HippelLindau disease: radiologic screening for visceral manifestations. Radiology. 1990;174: Choyke PL, Glenn GM, Walther MM, et al. The natural history of renal lesions in von Hippel-Lindau disease: a serial CT study in 28 patients. A]R Am] Roentgenol. 1992;159: Witten FR, O'Brien DP III, Sewell CW, Wheatley JK. Bilateral clear cell papillary cystadenoma of the epididymides presenting as infertility: an early manifestation of von Hippel-Lindau's syndrome. J Urol. 1985;133: Korn WT, Schatzki SC, DiSciullo AJ, Scully RE. Papillary cystadenoma of the broad ligament in von Hippel-Lindau disease. Am] Obstet Gynecol. 1990;163: Manski TJ, Heffner DK, Glenn GM, et al. Endolymphatic sac tumors: a source of morbid hearing loss in von Hippel-Lindau disease.]ama.1997;277: Seizinger BR, Smith 01, Filling-Katz MR, et al. Genetic flanking markers refine diagnostic criteria and provide insights into the genetics of von Hippel Lindau disease. Proc Natl Acad Sci USA. 1991;88: Chen F, Kishida T, Yao M, et al. Germline mutations in the von Hippel-Lindau disease tumor suppressor gene: correlations with phenotype. Hum Mutat. 1995;5: Glavac D, Neumann HP, Wittke C, et al. Mutations in the VHL tumor suppressor gene and associated lesions in families with von Hippel-Lindau disease from central Europe. Hum Genet. 1996; 98: Maher ER, Webster AR, Richards FM, et al. Phenotypic expression in von Hippel-Lindau disease: correlations with germline VHL gene mutations. J Med Genet. 1996;33: Knudson AG Jr. Mutation and cancer: statistical study of retinoblastoma. Proc Natl Acad Sci USA. 1971;68: Iliopoulos 0, Kaelin WG Jr. The molecular basis of von HippelLindau disease. Mol Med. 1997;3: Yao M, Latif F, Orcutt ML, et al. von Hippel-Lindau disease: identification of deletion mutations by pulsed-field gel electrophoresis. Hum Genet. 1993;92: Tory K, Brauch H, Linehan M, et al. Specific genetic change in tumors associated with von Hippel-Lindau disease. J Natl Cancer Inst.1989;81: Latif F, Tory K, Gnarra J, et al. Identification of the von HippelLindau disease tumor suppressor gene. Science. 1993;260: Gnarra JR, Tory K, Weng Y, et al. Mutations of the VHL tumour suppressor gene in renal carcinoma. Nat Genet. 1994;7:8590. Richards FM, Schofield PN, Fleming S, Maher ER. Expression of the von Hippel-Lindau disease tumour suppressor gene during human embryogenesis. Hum Mol Genet. 1996;5: Kessler PM, Vasavada SP, Rackley RR, et al. Expression of the von Hippel-Lindau tumor suppressor gene, VHL, in human fetal kidney and during mouse embryogenesis. Mol Med. 1995;1: Crossey PA, Richards FM, Foster K, et al. Identification of intragenic mutations in the von Hippel-Lindau disease tumour suppressor gene and correlation with disease phenotype. Hum Mol Genet. 1994;3: Richards FM, Crossey PA, Phipps ME, et al. Detailed mapping of germline deletions of the von Hippel-Lindau disease tumour suppressor gene. Hum Mol Genet. 1994;3: Whaley JM, Naglich J, Gelbert L, et al. Germ-line mutations in the von Hippel-Lindau tumor-suppressor gene are similar to somatic von Hippel-Lindau aberrations in sporadic renal cell carcinoma [published correction appears in Am] Hum Genet. 1995;56:356). Am] Hum Genet. 1994;55: Decker HJ, Neuhaus C, Jauch A, et al. Detection of a germline mutation and somatic homozygous loss of the von Hippel-Lindau tumor-suppressor gene in a family with a de novo mutation: a combined genetic study, including cytogenetics, PCR/SSCP, FISH, and CGH. Hum Genet. 1996;97: Brauch H, Kishida T, Glavac D, et al. von Hippel-Lindau (VHL) disease with pheochromocytoma in the Black Forest region of Germany: evidence for a founder effect. Hum Genet. 1995;95: Richards FM, Phipps ME, Latif F, et al. Mapping the von HippelLindau disease tumour suppressor gene: identification of germline deletions by pulsed field gel electrophoresis. Hum Mol Genet. 1993;2: Kishida T, Yao M, Chen F, Orcutt ML, Lerman MI, Zbar B. A novel donor splice site mutation associated with two mrnas in von Hippel-Lindau disease. Hum Mol Genet. 1994;3: Loeb DB, Pericak-Vance MA, Stajich JM, Vance JM. A novel mutation in the von Hippel-Lindau gene. Hum Mol Genet. 1994;3: Shuin T, Kondo K, Kaneko S, et al. Results of mutation analyses of von Hippel-Lindau disease gene in Japanese patients: comparison with results in United States and United Kingdom [in Japanese). Hinyokika Kiyo. 1995;41: Zbar B, Kishida T, Chen F, et al. Germline mutations in the von Hippel-Lindau disease (VHL) gene in families from North America, Europe, and Japan. Hum Mutat. 1996;8: Iliopoulos 0, Kibei A, Gray S, Kaelin WG Jr. Tumour suppression by the human von Hippel-Lindau gene product. Nat Med. 1995;1: Corless CL, Kibei AS, Iliopoulos 0, Kaelin WG Jf. Immunostaining of the von Hippel-Lindau gene product in normal and neoplastic human tissues. Hum Pathol. 1997;28:

8 272 von Rippel-Lindau Disease 75. Lee S. Chen DY. Humphrey JS. Gnarra JR, Linehan WM. Klausner RD. Nuclear/cytoplasmic localization of the von Hippel-Lindau tumor suppressor gene product is determined by cell density. Proc Natl Acad Sci USA. 1996;93: Los M, Jansen GH. Kaelin WG. Lips CJ. Blijham GH, Voest EE. Expression pattern of the von Hippel-Lindau protein in human tissues. Lab Invest. 1996;75: Duan DR. Humphrey JS. Chen DY. et al. Characterization of the VHL tumor suppressor gene product: localization, complex formation, and the effect of natural inactivating mutations. Proc Natl Acad Sci USA. 1995;92: Kibei A. Iliopoulos 0, DeCaprio JA. Kaelin WG Jr. Binding of the von Hippel-Lindau tumor suppressor protein to Elongin B and C. Science. 1995;269: Kishida T. Stackhouse TM, Chen F, Lerman MI, Zbar B. Cellular proteins that bind the von Hippel-Lindau disease gene product: mapping of binding domains and the effect of missense mutations. Cancer Res. 1995;55: Tsuchiya H. Iseda T, Hino 0. Identification of a novel protein (VB P-I) binding to the von Hippel-Lindau (VHL) tumor suppressor gene product. Cancer Res. 1996;56: Duan DR. Pause A. Burgess WHo et al. Inhibition of transcription elongation by the VHL tumor suppressor protein. Science. 1995;269: Aso T, Lane WS. Conaway JW. Conaway RC. Elongin (SIII): a multisubunit regulator of elongation by RNA polymerase II. Science.1995;269: Decker HJ. Weidt EJ. Brieger J. The von Hippel-Lindau tumor suppressor gene: a rare and intriguing disease opening new insight into basic mechanisms of carcinogenesis. Cancer Genet Cytogenet, 1997;93: Kolch W. Martiny-Baron G. Kieser A. Marme D. Regulation of the expression of the VEGF/VPS and its receptors: role in tumor angiogenesis. Breast Cancer Res Treat. 1995;36: Takahashi A. Sasaki H, Kim SJ, et al. Markedly increased amounts of messenger RNAs for vascular endothelial growth factor and placenta growth factor in renal cell carcinoma associated with angiogenesis. Cancer Res. 1994;54: Wizigmann-Voos S. Breier G. Risau W. Plate KH. Up-regulation of vascular endothelial growth factor and its receptors in von Hippel-Lindau disease-associated and sporadic hemangioblastomas. Cancer Res. 1995;55: Ikeda E, Achen MG. Breier G, Risau W. Hypoxia-induced transcriptional activation and increased mrna stability of vascular endothelial growth factor in C6 glioma cells. J Bioi Chern. 1995; 270: Gnarra JR. Zhou S. Merrill MJ, et al. Post-transcriptional regulation of vascular endothelial growth factor mrna by the product of the VHL tumor suppressor gene. Proc Nat! Acad Sci USA. 1996;93: Iliopoulos 0. Levy AP, Jiang C, Kaelin WG Jr, Goldberg MA. Negative regulation of hypoxia-inducible genes by the von Hippel Lindau protein. Proc Natl Acad Sci USA. 1996;93: Siemeister G. Weindel K. Mohrs K. Barleon B, Martiny-Baron G. Marme D. Reversion of deregulated expression of vascular endothelial growth factor in human renal carcinoma cells byvon Hippel Lindau tumor suppressor protein. Cancer Res. 1996;56: