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\section{The era of the genome-wide association study}  The completion of the Human Geneome Project in 2003 ushered in a new era of genomics, and with it the expection expectation  that complex genetic diseases could now be tackled. Armed with a complete reference genome, understanding the variability between humans became a major focus of the International HapMap Project [http://hapmap.ncbi.nlm.nih.gov] \cite{20811451}. 1184 1.6 million 11 different ethnic populations. Microarray. Consortia. WTCCC. What is GWAS. A genome-wide association study (GWAS) uses microarray technology to genotype hundreds of thousands (more recently millions) of single nucleotide polymorphisms (SNPs) from across the genome. Knowledge of linkage disequalibrium throughout the human genome allowed for intelligent selection of a non redundant set of SNPs that capture genetic variability across the human genome. The era of the GWAS had arrived.  The first seminal GWAS was published in 2007 by the Wellcome Trust Case Controlm Consortium (WTCCC).  \section{2009: The rebirth of Alzheimer's disease genetics}  Early attempts to perform a GWAS in late-onset AD suffered from small sample numbers. As a result the early GWAS were insufficiently powered to detect any genetic risk factors other than the strong APOE association. However, in 2009, each armed with a case-control cohort of greater than 5,000 samples, two European consortia published three new genes in LOAD; \textit{CLU}, \textit{PICALM} and \textit{CR1} \cite{19734902}\cite{19734903}. This was swiftly followed by a fourth US led effort, \textit{BIN1}, in 2010 \cite{20460622}. Data pooling and meta-analysis between the US (ADGC) and European groups (GERAD) resulted in a further five genes; \textit{ABCA7}, \textit{EPHA1}, \textit{MS4A} locus, \textit{CD2AP}, \textit{CD33} \cite{21460840} \cite{21460841}. The final traunch of genes came in 2013 as a result of international collaboration under the IGAP (International Genomics of Alzheimer's Disease Project) consortia; \textit{PTK2$\beta$}, \textit{SORL1}, \textit{HLA-DRB5/1}, \textit{SLC24A4}, \textit{CASS4}, \textit{CELF1}, \textit{ZCWPW1}, \textit{INPP5D}, \textit{MEF2C}, \textit{NME8} and \textit{FERMT2} \cite{24162737}. This GWAS is the most recent, and included 74,046 samples genotypes at over 7 million SNPs. In the space of only five years GWAS has given the field twenty new genetic loci. However, the true success of GWAS will be judged by how these genetic clues can be harnessed.