A total of 1 065 families were included in this study (comprising 1 406 patients with OCD and 2 895 individuals in total); 621 families were recruited and assessed specifically for this study at one of the five participating recruitment sites or the National Institute of Mental Health; 444 families had previously been evaluated in one of the earlier studies at Hopkins University or by one of the collaborating sites. The sample comprised of 460 complete trios (including an affected proband and both parents); 155 pedigrees with a proband and an unaffected sibling and 450 families with another structure (complex family structure). An additional 192 probands without an additional family member present in the study (singletons) were included. A breakdown of the families by site is found in Supplementary Table S1 .
For study inclusion, probands were required to meet DSM-IV criteria for OCD 23 with onset of obsessions and/or compulsions before the age of 18 years (mean = 9.4 years; SD=6.35). Subjects disease, schizophrenia, severe mental retardation that does not permit an evaluation to characterize the psychiatric disorder, Tourette disorder (TS), or OCD occurring exclusively in the context of depression (secondary OCD) were excluded. In addition, individuals were removed from the sample if they were previously diagnosed with brain pathology including brain tumors, Huntington’s Disease, Parkinson’s Disease, or Alzheimer’s Disease. Each case was evaluated by a PhD-level clinical psychologist using the Structured Clinical Interview for DSM-IV (SCID) modified and extended to include additional symptom and diagnostic information as indicated in thesupplementary material . Final diagnostic status was assigned based on the consensus of two psychiatrists or psychologists reviewing the case independently. Both parents of the proband were also recruited whenever possible. When parents were unavailable for participation, unaffected siblings were recruited. Genotyping was performed at the Johns Hopkins SNP Center using Illumina’s HumanOmniExpress bead chips (Illumina Inc., San Diego, CA, USA). More details on the diagnostic assessment and the genotyping process are provided in the supplementary materials and methods .
To increase the power of the study to detect significant association, we also included 1 984 unrelated controls (genotyped with Illumina’s HumanOMNI1-QUAD bead chip) from a previously published study on Parkinson’s disease (dbGaP accession number phs000196.v2.p1) 24 (link), 25 (link). Individuals with a self-reported or diagnosed neuropsychiatric disorder at the time of enrollment were excluded from the present study.
For study inclusion, probands were required to meet DSM-IV criteria for OCD 23 with onset of obsessions and/or compulsions before the age of 18 years (mean = 9.4 years; SD=6.35). Subjects disease, schizophrenia, severe mental retardation that does not permit an evaluation to characterize the psychiatric disorder, Tourette disorder (TS), or OCD occurring exclusively in the context of depression (secondary OCD) were excluded. In addition, individuals were removed from the sample if they were previously diagnosed with brain pathology including brain tumors, Huntington’s Disease, Parkinson’s Disease, or Alzheimer’s Disease. Each case was evaluated by a PhD-level clinical psychologist using the Structured Clinical Interview for DSM-IV (SCID) modified and extended to include additional symptom and diagnostic information as indicated in the
To increase the power of the study to detect significant association, we also included 1 984 unrelated controls (genotyped with Illumina’s HumanOMNI1-QUAD bead chip) from a previously published study on Parkinson’s disease (dbGaP accession number phs000196.v2.p1) 24 (link), 25 (link). Individuals with a self-reported or diagnosed neuropsychiatric disorder at the time of enrollment were excluded from the present study.
