Research interest into the genetics behind OCD continued, especially regarding what can be found within the human genome (the full set of genetic information).

This study by Dr. Simen and his team aimed to determine the number of copies of each segment of the human genome in people with OCD, and compare them to the genome of people without it. People often have two copies of each genome segment (one from the mother and one from the father), and research at the time found that people have more or less than the expected number of copies of certain regions, which are called copy number variants (CNVs). The team aimed to first identify CNVs that could be relevant for OCD in a smaller sample of people with and without OCD, and then compare those CNVs in larger samples.