Von Hippel-Lindau disease type 2 in a Chinese family with a VHL p.W88X truncation

Saturation genome editing maps the functional spectrum of pathogenic VHL alleles

To maximize the impact of precision medicine approaches, it is critical to identify genetic variants underlying disease and to accurately quantify their functional effects. A gene exemplifying the challenge of variant interpretation is the von Hippel-Lindautumor suppressor (VHL). VHL encodes an E3 ubiquitin ligase that regulates the cellular response to hypoxia. Germline pathogenic variants in VHL predispose patients to tumors including clear cell renal cell carcinoma (ccRCC) and pheochromocytoma, and somatic VHL mutations are frequently observed in sporadic renal cancer. Here we optimize and apply saturation genome editing to assay nearly all possible single-nucleotide variants (SNVs) across VHL's coding sequence. To delineate mechanisms, we quantify mRNA dosage effects and compare functional effects in isogenic cell lines. Function scores for 2,268 VHL SNVs identify a core set of pathogenic alleles driving ccRCC with perfect accuracy, inform differential risk across tumor types and reveal new mechanisms by which variants impact function. These results have immediate utility for classifying VHL variants encountered clinically and illustrate how precise functional measurements can resolve pleiotropic and dosage-dependent genotype-phenotype relationships across complete genes.

VHL syndrome without clear family history: A rare case report and literature review of Chinese patients

Objective

To analyze the clinical manifestations and imaging features of a hospitalized patient with intermittent headache who was finally diagnosed with von Hippel–Lindau (VHL) syndrome and to perform whole-exon gene detection to improve the understanding of the diagnosis and treatment strategies of the disease.

Methods

A case of suspected VHL syndrome in Shanxi Provincial People's Hospital was analyzed. Proband DNA was also extracted for whole exome sequencing and screened for causative mutation sites, which were validated by Sanger sequencing. The literature about VHL gene mutations in Chinese patients in the past 10 years were also reviewed.

Results

There is a heterozygous mutation site c.499C > G on the VHL gene on the short arm of chromosome 3 of the patient, which is a missense mutation. The mutation results in the substitution of arginine with glycine at amino acid 167 of the encoded protein, which may be primarily responsible for the disease in the patient with VHL syndrome. However, the mutation did not occur in other family members.

Conclusion

Early recognition and treatment of VHL syndrome can be available with genetic testing technology. Strengthening the understanding of this complex genetic disease and improving the diagnostic rate of VHL syndrome are helpful for the precise treatment of patients with this disease, which may help prolong the survival time of patients to a certain extent and improve their quality of life.

Molecular-genetic diagnostics of von Hippel-Lindau syndrome (VHL) in Bulgaria: first complex mutation event in the VHL gene

Von Hippel-Lindau syndrome is an autosomal-dominant disease characterized by the formation of various tumours and cysts in many different parts of the body. Von Hippel-Lindau syndrome is caused by VHL gene mutations leading to production of impaired tumor suppressor Von Hippel-Lindau syndrome protein or its complete absence.

PURPOSE

To study five patients with clinically suspected Von Hippel-Lindau syndrome, who were referred for molecular genetic testing.

METHODS

Sanger sequencing of the coding regions of the VHL gene.

RESULTS

Five clinically relevant germline mutations were detected. One of the pathogenic variants has not been previously reported. This novel mutation is a complex mutation event combining a duplication and an indel, rearranging exon 3 of the VHL gene - c. [516_517dupGTCAAGCCT; 532_542delCTGGACATCGTinsATTA], p. (Glu173Serfs*4).

CONCLUSION

Overall, our results showed that the diagnosis of Von Hippel-Lindau syndrome in our country is difficult most probably because of its heterogeneous clinical manifestation and insufficient knowledge on the diagnostic criteria for the disease. From genetic point of view our results add some novel data on the mutation profile of the VHL gene. In order to prove or revise the diagnosis, early genetic testing is strongly recommended in affected patients and their family members to ensure appropriate follow-up and treatment of the malignancies.

VHL Germline Mutations in Argentinian Patients with Clinical Diagnoses or Single Typical Manifestations of Type 1 von Hippel-Lindau Disease

AIMS

von Hippel-Lindau (VHL) disease is caused by mutations in the VHL tumor suppressor gene. As tumors that develop in the context of VHL also occur in a sporadic context, the frequency of this syndrome may be underestimated. Our aim was to identify VHL gene mutations in Argentinian patients who fulfilled the clinical criteria for type 1 VHL disease and in patients with VHL-associated manifestations that did not meet these criteria.

METHODS

We performed a retrospective cohort study, including patients who met current diagnostic criteria for type 1 VHL (Group 1, n = 19) and patients with VHL-associated manifestations that did not meet these criteria (Group 2, n = 21). Genomic DNA was extracted from peripheral blood leukocytes. Mutation analysis involved DNA sequencing, while large deletions were determined by universal primer quantitative fluorescent multiplex polymerase chain reaction (UPQFM-PCR) and multiplex ligation-dependent probe amplification (MLPA) analysis.

RESULTS

VHL mutations were detected in 16/19 (84.2%) patients in Group 1 and included: gross deletions (4/16); nonsense mutations (6/16); frameshift mutations (4/16); missense mutations (1/16); and splicing mutations (1/16). Three of these mutations were novel. No alterations were found in 3 of 19 VHL patients. In Group 2, one nonsense VHL mutation was detected in a young patient with a solitary central nervous system hemangioblastoma without familial history. A study of 30 first-degree relatives revealed four carriers with VHL mutations.

CONCLUSIONS

We found three novel mutations in the VHL gene in our population. Our results emphasize the importance of a complete genetic study of VHL to confirm type 1 VHL disease, not only in patients with clinical diagnostic criteria but also in those presenting a single typical manifestation.