Role of regulatory elements in the genetic determination of VWF level in Von Willebrand disease and healthy individuals

Von Willebrand Factor (VWF) is a protein needed to make the blood clot. VWF is stored and released into the bloodstream by the cells lining the blood vessels (endothelial cells). VWF is also stored in the smallest type of cells in the blood, called platelets. Low VWF in the bloodstream leads to a bleeding disorder called Von Willebrand disease (VWD), affecting 10,000 people in the UK. It negatively impacts on patients' quality of life. The flipside is that the blood clots too readily resulting in conditions such as deep vein thrombosis (DVT). Studies with a large number of participants have shown that a high level of VWF is a risk factor for DVT. The level of VWF in the blood is for a large part controlled by our genes. Differences in the DNA between individuals are called variants. The variants that lead to VWD are known in every 7-8 out of 10 patients, although in some patients ascribing the variant causing VWD is challenging because of lack of data from enough healthy volunteers. Not all of the variants that explain how VWD is inherited have yet been mapped out by scientists. Understanding more about VWF inheritance could therefore provide more people with VWD an accurate genetic diagnosis, enabling them to guide their own family members about their chances of being affected. Scientists need also to find out more about which variants are associated with elevated VWF levels as this information could - in the future - potentially be used to guide people, like you about the risk of a DVT. Reading the DNA code is done by sequencing and the word genomics is the term for the reading and analysis of the entire DNA code (or genome). Cambridge scientists in Professor Ouwehand's team have been at the forefront of this. It is becoming apparent that there are many interactions between different parts of the genome. The genome contains many elements that work like 'switches and dimmers' controlling thousands of our genes ('the light bulbs'). Scientists from the BLUEPRINT project are mapping out the links between the switches and dimmers and the genes they control. They have also done this for the cells in our body that produce VWF and we can now answer the question whether in some VWD patients the gene for VWF does not work because one of the switches or dimmers is faulty. Work just completed by our scientists has mapped out specific interactions between highly active dimmers called super dimmers for the VWF gene and its neighbour, CD9 (referred to as VWF-CD9). In a study linking blood cell features to variants in 170,000 people, variants were identified in a super dimmer that controls VWF-CD9 in the cells from which platelets originate (megakaryocytes). Because super dimmers can control more than one gene and their effect on the connected genes are not always clear it is important to examine this in relevant types of cells in the laboratory. Using stem cells (which can mature into any type of cell), and 'DNA scissors' to remove the super-dimmer, the stem cells were turned into megakaryocytes which contained the super-dimmer and those that didn't. The megakaryocytes without the super-dimmer had higher levels of VWF and almost no CD9, than those that didn't. In my research project blood samples from 1000 VWD patients from across seven UK hospitals will be collected and DNA extracted for sequencing. Variants will be looked for in the VWF gene and a closeby region including switches and dimmers. The same will be done for 42,000 volunteers without VWD participating in the 100 000 Genomes Project. I will then work with experts in statistics & computing to analyse for connections between variants in the switches and dimmers for VWF and VWF levels. To confirm the effect of my findings I will use 'DNA scissors' to engineer stem cells with & without the variant in them and mature them not only into megakaryocytes and platelets but also the cells lining blood vessels so I can study how these variants affect VWF production.