Molecular genetic aspects of Von Hippel-Lindau (VHL) disease and criteria for DNA analysis in subjects at risk

ISOLATED PARAGANGLIOMA IN A PATIENT WITH VHL P.L163F MUTATION

Objective

Paragangliomas (PGLs) are one of the many neoplasms associated with von Hippel-Lindau (VHL) disease. VHL disease type 2C is a unique subtype characterized by the presence of a PGL or pheochromocytoma without other VHL-associated neoplasms. This report describes a rare germline mutation in the VHL gene in a patient with isolated PGL.

Methods

The clinical presentation, urinary metanephrines and normetanephrines, computed tomography scan, meta-iodobenzylguanidine scintiscan, surgical pathology, and genetic testing of a patient with PGL and a rare VHL gene mutation are described. A literature review is also presented.

Results

A 23-year-old, Indian woman was incidentally found to have an indeterminate 4.2 × 3.6 × 3.2-cm mass adjacent to the liver. A 36-year-old first cousin was recently diagnosed with a PGL. Her 24-hour urinary metanephrines were 6,886 μg/g creatinine (reference range is 81 to 330 μg/g creatinine) and normetanephrines were 6,810 μg/g creatinine (reference range is 20 to 158 μg/g creatinine). Surgical pathology revealed a PGL adjacent to a normal adrenal gland. Genetic testing revealed a mutation in VHL p.L163F. Surveillance for other tumors associated with VHL disease has been negative thus far. Her cousin has not undergone genetic testing despite recommendations to do so.

Conclusion

We present the first reported case of PGL in a patient with VHL disease caused by a missense mutation in VHL p.L163F. To date, reports of this rare mutation have only involved patients with pheochromocytoma and without other tumors associated with VHL disease, suggesting that VHL p.L163F mutation may cause a VHL disease type 2C phenotype.

The McGill Interactive Pediatric OncoGenetic Guidelines: An approach to identifying pediatric oncology patients most likely to benefit from a genetic evaluation

Identifying cancer predisposition syndromes in children with tumors is crucial, yet few clinical guidelines exist to identify children at high risk of having germline mutations. The McGill Interactive Pediatric OncoGenetic Guidelines project aims to create a validated pediatric guideline in the form of a smartphone/tablet application using algorithms to process clinical data and help determine whether to refer a child for genetic assessment. This paper discusses the initial stages of the project, focusing on its overall structure, the methodology underpinning the algorithms, and the upcoming algorithm validation process.

von Hippel-Lindau gene mutation in non-syndromic familial pheochromocytomas

Approximately 50% of patients with non-syndromic familial pheochromocytomas had germline von Hippel-Lindau (VHL) gene mutations, but no reports on the subject were available in China. A total of five unrelated Chinese families with non-syndromic familial pheochromocytomas were screened for VHL gene mutation by polymerase chain reaction (PCR) and subsequent direct sequencing. Missense germline mutations of VHL gene were detected in four of the five families. Arg161Gln (695G-A) mutation was found in two families, and the other two families had Leu163Phe (700C-T) and Arg167Trp (712C-T) mutation, respectively. In conclusion, VHL gene may have frequent mutation in Chinese patients with non-syndromic familial pheochromocytomas.

Hemangioblastomas of Central Nervous System: Molecular Genetic Analysis and Clinical Management

OBJECTIVE

Hemangioblastomas of the central nervous system (CNS) are benign neoplasms that may occur sporadically or in association with von Hippel-Lindau (VHL) disease. The proportion of primary symptomatic hemangioblastomas associated with VHL disease is estimated to be from 10 to 40%, but it seems to be underestimated. We investigated the frequency of VHL germline mutation in patients with symptomatic CNS hemangioblastoma without evidence of VHL disease to define the role of molecular genetic analysis in the management of such patients and their relatives.

METHODS

We analyzed 14 patients (6 female and 8 male; mean age, 43.5 yr) with no family history and no other clinical manifestations of VHL disease who had been operated on for symptomatic CNS hemangioblastoma. Exons 1, 2, and 3 of the VHL gene and their immediately flanking sequences were amplified by use of polymerase chain reaction followed by analysis with denaturing high-performance liquid chromatography and sequencing the anomalous samples.

RESULTS

Germline mutations of the VHL gene were identified in 2 (14%) of 14 patients. VHL gene mutation analysis was performed in both patients' family members, which showed another affected asymptomatic subject for VHL disease. The affected subjects were recommended for VHL disease surveillance protocol.

CONCLUSION

Molecular genetic analysis is a safer and more specific instrument to confirm or exclude VHL disease in patients with CNS hemangioblastoma, a negative family history, or absence of other known manifestations of the disease. Early identification of VHL mutation gene carriers is important for reducing disease morbidity and mortality. Nonsymptomatic family members will benefit from early VHL disease diagnosis or by being excluded as at-risk subjects, reducing the psychological and economic burden of screening and surveillance protocols.