1. Characterization of VHL promoter variants in patients suspected of Von Hippel Lindau Saleh Albanyan, Rachel Giles, Raymond H Kim, MD/PhD Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of Toronto, Department of Nephrology and Hypertension UMC Utrecht Division of Medical Oncology and Hematology, Department of Medicine, University of Toronto, University Health Network, Toronto, Canada
Introduction:
Von Hippel-Lindau disease (VHL) is a hereditary cancer syndrome in which carriers are at increased risk of developing a variety of tumors in multiple organ systems.
A clinical diagnosis of VHL is determined by the presence of specific clinical manifestations while molecular genetic diagnosis results from a pathogenic variant in the VHL gene.
The majority of mutations occur in VHL coding exons and DNA analysis of these regions has a sensitivity of nearly 100%.
Patients & Results:
Family 1:
 53 year old male presenting with a renal cyst and pancreatic nodule found to have a Variant of uncertain significance (VUS) in the 5’ UTR of VHL (c-61_-51 dup11).
Variant was examined in his 3 children, and was found in his daughter and who had negative VHL phenotyping (Figure 1)
Transcript analysis by RT-PCR ( daughter’s peripheral blood lymphocytes) revealed 61% RNA expression VHL transcripts compared to healthy control.
Protein analysis with western blotting of the VHL protein in peripheral blood lymphocytes also showed decreased protein expression.
( Figure 2)
Family 2:
22 year old female presenting with 2 right sided renal masses on abdominal ultrasound and multiple pancreatic cysts found to have a VUS in the 5’ UTR of VHL (c.-77_-32del)
This variant segregated with 2 affected family members (Figure 1)
Transcript analysis by RT-PCR was performed and revealed that our patient expressed 45% of normal VHL transcripts decreased VHL protein gene expression(figure2).  
Protein analysis with western blotting of the VHL protein using the patient’s lymphocytes showed marked decreased expression   
CONCLUSIONS:
RNA and protein studies in these families were taken in context of the clinical manifestations (More marked decrease in Patient 2)
Both promoter variants may play a role in the clinical phenotype in both families, it is likely more contributory in the second family.
Promoter regions could be of importance for the molecular characterization of VHL patients that have no variations in the coding region.
we propose extending the molecular analysis of highly suspicious VHL cases to include the regulatory regions of the gene along with RNA and protein studies