The mystery of missing heritability has plagued geneticists ever since genome-wide association studies, known as GWAS, became a popular method for seeking out genetic cauess of human disease. While many of these studies located genetic variants associated with their disease of interest, these variants could only explain a portion of the heritability for these diseases, as measured by familial patterns. The gap led many scientists to propose a role for rare genetic variants not tested in standard GWAS, or for combinations of variants.
A breakthrough in that debate was reached today in a paper co-authored by CI Senior Fellow Nancy Cox in PLoS Genetics. A new analytic method applied to genetic data from individuals with obsessive-compulsive disorder (OCD) and Tourette's syndrome found important new clues to the "genetic architecture" of the psychiatric diseases, according to a news release from the University of Chicago Medicine and Massachusetts General Hospital. An approach called genome-wide complex trait analysis allowed the researchers to discover combinations of variants and rare variants that contributed to the two diseases' heritability.
The results revealed new insights about the similarities and differences of OCD and Tourette's, Cox said. "Despite the fact that we confirm there is shared genetic liability between these two disorders, we also show there are notable differences in the types of genetic variants that contribute to risk. TS appears to derive about 20 percent of genetic susceptibility from rare variants, while OCD appears to derive all of its susceptibility from variants that are quite common, which is something that has not been seen before."
For more on the study and its implications for treatment of these psychiatric disorders, see the news release and the original paper.