While studying the proteins and molecules which “turn genes on and off,” called the epigenome, researchers were surprised to find common ground in the causes of rheumatoid arthritis and the incurable and fatal brain disease Huntington’s.

“We did not expect to find an overlap between rheumatoid arthritis and Huntington’s disease, but discovering the unexpected was the reason that we developed this technology,” said Gary Firestein, a rheumatologist and associate vice chancellor and dean of translational medicine at the University of California, San Diego School of Medicine, in a news release. “Now that we have uncovered this connection, we hope that it opens a door for treatment options for people living with either disease.”

Firestein’s research with colleagues at UCSD and at Mount Sinai’s Icahn School of Medicine, which used an algorithm they created called EpiSig, appears in Nature Communications. The tool helped the researchers process an enormous amount of data.

Epigenetics, which studies gene structure alteration that doesn’t necessarily change the DNA, has become “increasingly important in understanding many disorders, as epigenetic changes can be influenced by a variety of environmental factors, including aging, activity, and lifestyle choices,” wrote Jack Cush, of Baylor University Medical Center, in MedPage Today.

“Future studies are required to validate the large number of unanticipated targets and pathways as well as explore diversity between patients and individualize treatment,” Firestein and colleagues wrote in the study.