 The human genome project also produced other advances, not expected to be accomplished until much later. These included an advanced draft of the mouse genome and an initial draft of the rat genome. Medical researchers did not wait to use data from the human genome project. When the project began in 1990, fewer than 100 human disease genes had been identified. At the project's conclusion in 2003, the number of identified disease genes had risen to more than 1,400. The human genome project focused on the DNA sequence of an individual. The next step was to analyze DNA sequences from different populations. This catalog of human genetic variation was called the HAPMAP. Completed in 2005, the HAPMAP used single nucleotide polymorphisms called SNPs to identify large blocks of DNA sequence called haplotypes that tend to be inherited together. To use the data, researchers compare haplotypes between people with and without a disease. Haplotypes shared by people with the disease are then examined in detail to look for associated genes. Already, scientists have used its data to identify a gene associated with age-related macular degeneration, a disease responsible for blindness among the elderly. It is expected that the HAPMAP will play an important role in identifying many more disease genes in the future.