Researchers at University of Chicago have made use of diseases with known genetic causes to conduct one of the most expansive analyses of genetic factors at play in complex diseases.

"For the first time we've found that almost every complex disease has a unique set of associations with single-gene diseases. This essentially gives us 'barcodes' of specific gene loci, which we can use to help untangle the complex genetics of complex diseases," said Andrey Rzhetsky, PhD, professor of genetic medicine and human genetics at the University of Chicago, who led the study.
The majority of human diseases are complex and caused by a combination of genetic, environmental and lifestyle factors. On the other end of the spectrum are Mendelian diseases such as cystic fibrosis and sickle-cell anemia, which are caused by abnormalities to a single gene. Some Mendelian disorders are known to predispose patients to certain complex diseases, but these co-occurrences have thus far only been studied on a small-scale basis.
To expose any underlying shared genetic structures between these disease categories, Rzhetsky and his team developed computational algorithms to parse more than 120 million patient billing records from hospitals systems across the U.S. and from nearly the entire population of Demark. They looked for trends in comorbidity, or the occurrence of both complex and Mendelian disease in the same patient, that were higher than expected from random chance. They studied these correlations in 65 complex diseases affecting almost every system in the body, including arthritis, depression and lung cancer, and in 95 Mendelian disease groups (representing 213 disorders).
Source-Eurekalert