GCTA has now been applied to a number of complex traits, including TS and OCD (Table S10). Results from all of these analyses show that common interrogated variants account for a significant proportion of heritability estimated from twin and family studies [4]–[8], . Depending on the phenotype and original literature estimates, the proportion of heritability explained by common variation varies across different disorders from essentially all estimated heritability, as observed in autism, multiple sclerosis and von Willebrand's factor, to roughly half of the estimated heritability, as observed in height, schizophrenia, and type 1 diabetes. This study represents the first effort to use genome-wide genotype data to determine the heritability of two related neuropsychiatric disorders, OCD and TS. The narrow-sense heritability of each disorder (h2 GCTA = 0.58 for TS and 0.37 for OCD) correspond well with previously reported heritability estimates from family and twin studies [17], [19], [20], [21], [22], [23]–[25], [26], [27], [28], [29], [49] suggesting that there is little, if any, heritability “missing” (i.e., unassayed). While previous TS and OCD GWAS have been underpowered to identify individual susceptibility
