The Human Epigenome Project (HEP) was a few years after the completion of the Human Genome Project. Although HEP had many goals, its main purpose was to map the entire human genome by observing DNA methylation patterns of all human genes (21). Being one of the only traceable epigenetic mechanism, methylation is the focus of HEP (22). Naturally, methylation occurs on cytosine bases at CpG sequences and plays a role in controlling the correct expression of genes (23). "Differentially methylated cytosines give rise to distinct patterns specific fortissue type and disease state", which are methylation variable positions. MVPs are common epigenetic markers and is the focus of the HEP (23). “In October 2000, the Human Epigenome Consortium (the Sanger Institute, Epigenomics AG, and the Centre National de Génotypage in Evry, France) started a European Union-funded pilot project to map the methylation sites within the major histocompatibility complex (MHC) region in seven different human tissues." Rather than look at all the DNA methylation sites throughout the entire MHC region, they want to look at the 150 expressed genes within this region. For each gene, the scientists chose two areas to analyse for methylation, each about 500 base pairs long. The promoter regions are where the elements that control gene expression are usually located, and DNA methylation occurs at cytosine residues within CpG motifs, hence the choice of CpG-rich regions. During the three-year pilot study, more than 100,000 sites was determined for the methylation status (53). The results were analysed to show where there were methylation differences in the MHC between different tissues, which is shown in the image below (53).