Associations between VHL genotype and clinical phenotype in familial von Hippel-Lindau disease

Present status of germline findings in precision medicine for Japanese cancer patients: issues in the current system

OBJECTIVE

Since 2019, precision cancer medicine has been covered by national insurance in Japan; however, to date, germline findings have not been fully reported. The aim of this study was to evaluate the current status and raise a problem of germline finding analysis and disclosure in Japanese precision cancer medicine.

METHODS

Germline findings of 52 genes were examined in 296 cases with advanced cancer by a case series study.

RESULTS

Six (2.0%) cases were examined by the Oncoguide™ NCC Oncopanel with germline testing, but no germline findings were reported. The remaining 290 (98.0%) cases were analyzed by FoundationOne® CDx (tumor-only testing), which recognized 404 pathogenic variants; those of BRCA1/2 were recognized in 16 (5.5%) tumors. Our institutional algorithm suggested 39 candidate germline findings in 34 cases, while the public algorithm listed at least 91 candidate germline findings. Four germline findings had been previously identified (BRCA1: 3 and ATM: 1). Nine of 30 cases with candidate germline findings excluding these known germline findings refused or deferred germline testing. Only 4 of 16 cases that received counseling underwent germline testing, and those 4 revealed 3 germline findings (BRCA2, CDK4 and RAD51C); in total, 8 (2.7%) germline findings were revealed. Reasons for refusing genetic counseling and/or germline testing included extra hospital visits, added expense for germline testing due to limited national insurance coverage, poor patient physical condition and no known family members associated with the possible germline finding.

CONCLUSIONS

In current Japanese precision cancer medicine, only a small fraction of the patients undergoes germline testing and demonstrated germline finding. The current results suggested a need for earlier indications for precision cancer medicine, broader insurance coverage and more efficient germline finding prediction algorithms, to increase the number of germline testings and to improve the following managements.

Clinical manifestations and genetic analysis of a family with neurofibromatosis type 2

BACKGROUND

Neurofibromatosis type 2 (NF2) is an autosomal dominantly inherited disease with slow, yet potentially life-threatening progression.

OBJECTIVE

We describe the clinical manifestations and genetic profile of a family with NF2.

METHODS

We enrolled a 16-member family with NF2. We collected clinical examinations and imaging information. Genetic analysis was conducted through multiplex ligation-dependent probe amplification (MLPA). The SALSA MLPA probemix P044-B2 NF2 kit was used to detect genetic variations in genomic upstream and 17 exons of the NF2 gene.

RESULTS

The most common clinical manifestation was hearing impairment (37.5%), followed by tinnitus (18.8%). Four participants had vestibular schwannoma: 2 were bilateral and 2 unilateral, and tumor size ranged from 86.3 to 5064 mm³. A weak correlation between hearing impairment and tumor size was observed. Genetic analysis revealed that the DNA dosages of exons 9, 10, and 11 of the NF2 gene in 3 diseased family members (participants #3, #5, and #11) were higher than those in the controls. However, we could not detect an indicative abnormal DNA dosage of NF2 in participant #6 despite such a dosage being considered a diagnostic indicator of NF2.

CONCLUSIONS

Hearing impairment was the most common clinical manifestation in this family. The NF2 gene is a gene of interest that warrants familial genetic screening.

Pheochromocytomas and paragangliomas in von Hippel-Lindau disease: not a needle in a haystack

OBJECTIVE

Pheochromocytomas are a hallmark feature of von Hippel-Lindau disease (vHL). To our knowledge, this is the first systematic review with meta-analysis evaluating the frequency of pheochromocytomas and/or paragangliomas (PPGLs) in patients with vHL, as well as among patients with different vHL subtypes.

DESIGN

Systematic review with meta-analysis.

METHODS

We searched on MEDLINE, Scopus, and Web of Science. We included primary studies assessing participants with vHL and reporting on the frequency of PPGL. We performed random-effects meta-analysis to quantitatively assess the frequency of PPGL, followed by meta-regression and subgroup analysis. Risk of bias analysis was performed to assess primary studies' methodological quality.

RESULTS

We included 80 primary studies. In 4263 patients with vHL, the pooled frequency of PPGL was 19.4% (95% CI = 15.9-23.6%, I2 = 86.1%). The frequency increased to 60.0% in patients with vHL type 2 (95% CI = 53.4-66.3%, I2 = 54.6%) and was determined to be of 58.2% in patients with vHL type 2A (95% CI = 49.7-66.3%, I2 = 36.2%), compared to 49.8% in vHL type 2B (95% CI = 39.9-59.7%, I2 = 42.7%), and 84.1% in vHL type 2C (95% CI = 75.1-93.1%, I2 = 0%). In meta-regression analysis, more recent studies were associated with a higher frequency of PPGL. All studies had at least one internal validity item classified as 'high risk of bias,' with 13% studies having low risk of bias in all external validity items.

CONCLUSIONS

PPGLs are a common manifestation of vHL. Despite methodological limitations and differences across primary studies, our results point to the importance of PPGL screening in patients with vHL.

Roles of Loss of Chromosome 14q Allele in the Prognosis of Renal Cell Carcinoma with C-reactive Protein Abnormity

Background:

Renal cell carcinoma (RCC) is frequently associated with paraneoplastic inflammatory syndrome (PIS). This study aimed at exploring the connections between the survival rate and specific gene alterations and the potential mechanism.

Methods:

We retrospectively studied 69 surgical RCC cases from August 2014 to February 2016, including 18 cases of clear cell RCC (ccRCC) demonstrating elevated pretreatment serum C-reactive protein (CRP, Group A). Twelve of the 18 cases were symptomized with febrile episode. We also selected 49 cases of ccRCC with normal pretreatment CRP (Group B). Using 22 microsatellite markers, we compared the incidence of loss of heterozygosity (LOH) between Group A and Group B. All statistical tests are two-sided.

Results:

The 3p LOH was common in both Group A (89%) and Group B (92%). The frequency of 14q LOH in Group A (16 of 18) was higher than Group B (4 of 49, χ² = 40.97 P < 0.0001). The 3p and 14q LOH were the characteristics of ccRCC with elevated acute phase reactants, including PIS, regardless of the presence of metastasis. On the contrary, 14q LOH was a rare genomic alternation in advanced-staged ccRCC without PIS. The overall survival of patients with elevated CRP (33.3%) was lower than its counterparts (6.1%, hazard ratio=1.852, P < 0.0001) in Kaplan-Meier curve.

Conclusions:

The results imply that the disruption of a 14q gene(s) might result in not only the inflammatory manifestations in the tumor host but also the poor survival rate as well. The isolation of the gene(s) on 14q might be a vital goal in the treatment of PIS-associated RCC.

Development of Database and Genomic Medicine for von Hippel-Lindau Disease in Japan

von Hippel-Lindau (VHL) disease is a hereditary tumor disease in which tumors develop in multiple organs, not only as hemangioblastomas (HBs) in the central nervous system, but also as kidney tumors, pheochromocytomas, and so on. Much about the epidemiology of VHL disease remained unknown until fairly recently in Japan, leading to calls for the establishment of a VHL disease epidemiological database in Japanese. To elucidate its epidemiology in Japan, the Japanese Ministry of Health, Labour and Welfare created the VHL Disease Study Group, which was put in charge of carrying out a nationwide epidemiological survey. The survey found close to 400 Japanese VHL disease patients throughout the country. Based on those results, the VHL Disease Study Group created the VHL Disease Treatment Guideline and also a severity classification. It is thought that the prognosis of VHL disease patients can be improved by performing genetic diagnosis and careful follow-up. Accordingly, the University of Tokyo Hospital put in place an in-hospital system for implementing genomic medicine for VHL disease based on genetic diagnosis. For that system, it was especially important to establish (I) accurate genetic diagnostic techniques, (II) genetic counseling capabilities for the patients and their families, and (III) a system of cooperation among multiple departments, including urology departments, and so on. Further elucidation of the epidemiology and the development of genomic medicine are needed to improve the treatment results of VHL disease in Japan.

Identification of the first germline HRPT2 whole-gene deletion in a patient with primary hyperparathyroidism

OBJECTIVE

Germline mutations in the HRPT2 gene are associated with the hereditary hyperparathyroidism-jaw tumour syndrome (HPT-JT) and a subset of familial isolated hyperparathyroidism (FIHP). Somatic HRPT2 mutations are detected in sporadic parathyroid carcinomas and less frequently in cystic adenomas. The purpose of this study was to investigate the underlying HRPT2 defect in a young patient with symptomatic hyperparathyroidism due to an apparently sporadic parathyroid adenoma with cystic features.

DESIGN AND METHODS

HRPT2 mutations in the patient's genomic and parathyroid tumour DNA were screened by PCR-based sequencing. Tumour loss of heterozygosity (LOH) at the HRPT2 locus was assessed with microsatellite markers. A large germline HRPT2 deletion was investigated by real-time quantitative PCR analysis (qPCR). Genomic DNA losses were also appraised by chromosomal comparative genomic hybridization (cCGH).

RESULTS

No germline HRPT2 point mutation was detected by direct sequencing. A novel hemizygous HRPT2 somatic mutation (c.32delA) was identified in the tumour. Apparent constitutional homozygosity for HRPT2 flanking microsatellite markers, and absence of LOH at a distal marker, suggested a large germline deletion. Gene dose mapping by qPCR unveiled a de novo deletion of the whole HRPT2 gene and adjacent loci (<9·3 Mb in size). cCGH confirmed germline DNA loss involving the HRPT2 locus.

CONCLUSIONS

We report the first large germline deletion of the HRPT2 gene, which was not detectable by conventional PCR-based sequencing methods. This finding emphasizes that qPCR should be implemented in HRPT2 molecular analysis, which may improve genetic assessment and clinical management of patients with FIHP and HPT-JT.

A vitronectin M381T polymorphism increases risk of hemangioblastoma in patients with VHL gene defect

Hemangioblastomas, highly vascular tumors, occur sporadically or associated with von Hippel-Lindau (VHL) disease. Diverse mutations in the VHL gene inactivate the VHL protein and constitute the molecular etiology of the disease. Changes in VHL gene were analyzed in patients with multiplex ligation-dependent probe amplification and single-strand conformation polymorphism analyses. We report here that other angiogenesis-related changes in vitronectin were identified with 2D electrophoresis of plasma samples and restriction fragment length polymorphisms. Our findings revealed that most patients (80.0%) with a familial VHL deletion carried the threonine (T) allele at vitronectin codon 381. Adults simultaneously carrying a VHL defect and the T allele were 5.0-fold more likely to be affected by VHL disease than were methionine/methionine (M/M) homozygotes carrying a VHL defect. Patients with sporadic hemangioblastoma, C-terminally truncated VHL protein or a large deletion in the VHL gene, and the T allele were 18.0-fold more likely to develop recurrent disease. Taken together, individuals with mutated VHL are more likely to be affected by familial or recurrent sporadic hemangioblastoma when carrying the M/T or T/T genotype at codon 381 of vitronectin.

Unambiguous molecular detections with multiple genetic approach for the complicated chromosome 22q11 deletion syndrome

Background

Chromosome 22q11 deletion syndrome (22q11DS) causes a developmental disorder during the embryonic stage, usually because of hemizygous deletions. The clinical pictures of patients with 22q11DS vary because of polymorphisms: on average, approximately 93% of affected individuals have a de novo deletion of 22q11, and the rest have inherited the same deletion from a parent. Methods using multiple genetic markers are thus important for the accurate detection of these microdeletions.

Methods

We studied 12 babies suspected to carry 22q11DS and 18 age-matched healthy controls from unrelated Taiwanese families. We determined genomic variance using microarray-based comparative genomic hybridization (array-CGH), quantitative real-time polymerase chain reaction (qPCR) and multiplex ligation-dependent probe amplification (MLPA).

Results

Changes in genomic copy number were significantly associated with clinical manifestations for the classical criteria of 22q11DS using MPLA and qPCR (p < 0.01). An identical deletion was shown in three affected infants by MLPA. These reduced DNA dosages were also obtained partially using array-CGH and confirmed by qPCR but with some differences in deletion size.

Conclusion

Both MLPA and qPCR could produce a clearly defined range of deleted genomic DNA, whereas there must be a deleted genome that is not distinguishable using MLPA. These data demonstrate that such multiple genetic approaches are necessary for the unambiguous molecular detection of these types of complicated genomic syndromes.