with what is called “missing heritability” in the literature, is often seen with other phenotypes, and is interpreted to indicate that rare variants and genetic mechanisms besides additive polygenicity are contributing to heritability. For antisaccade eye tracking error and overall startle amplitude, there is little evidence of missing heritability. While this could indicate that the genetic architecture of these endophenotypes is different from the others, the standard errors of these GCTA estimates across measures are large and overlapping, indicating that replication is desired to rule out the possibility that chance fluctuations based on sample characteristics account for the SNP heritability differences across endophenotypes. The SNP heritability of the two modulated startle measures is essentially zero, supporting the conclusion that startle difference scores are not heritable and likely poor endophenotype candidates despite the substantial literature linking them to several psychiatric disorders.
