Researchers and pharmaceutical companies have known for years that genome sequencing holds the key to unlocking new disease-curing drugs, and now that the price per genome has decreased significantly, they can finally do it.

About five years ago, it cost nearly $20,000 to map one genome. Now it’s only about $1,500. Pharmaceutical companies are capitalizing on the advancements in technology to sequence the DNA of large patient populations in the hopes of identifying rare genes that cause illness, as well as ones that prevent it.

The amount of DNA sequencing being completed by various companies is substantial. In January 2014, Regeneron Pharmaceuticals Inc., made plans to sequence DNA from up to 250,000 patient volunteers. Earlier this year, Roche Holding AG’s Genentech unit signed a deal to analyze genomes from hundreds of thousands of patients in order to identify new drug targets. And those are just two companies among many.

Tim Harris, a senior vice president at Biogen who heads the company’s newly formed precision medicine group, hopes that DNA sequencing of patient volunteers will help them better understand how diseases operate.

“What has changed fundamentally is not the philosophy that we need to understand more about disease by looking at genetics,” Harris said. “What has changed is our ability to do it.”