Cross-twin/sibling within trait and cross-twin/sibling cross-trait brain volume correlations; r (95% CI)
| Region | Within-twin correlations with schizophrenia | Within-twin pair correlations | Cross-twin pair correlation (twin 1) with schizophrenia (twin 2)* | ||
|---|---|---|---|---|---|
| MZ | DZ | MZ | DZ | ||
| Whole brain | −0.26 (−0.39 to −0.11) | 0.89 (0.84 to 0.93) | 0.65 (0.08 to 0.83) | −0.22 (−0.35 to −0.07) | −0.23 (−0.43 to 0.03) |
| Grey matter | −0.25 (−0.39 to −0.11) | 0.87 (0.80 to 0.91) | 0.68 (0.26 to 0.84) | −0.21 (−0.35 to −0.07) | −0.22 (−0.43 to 0.03) |
| White matter | −0.18 (−0.32 to −0.04) | 0.85 (0.77 to 0.91) | 0.45 (−0.38 to 0.74) | −0.15 (−0.29 to −0.01) | −0.13 (−0.38 to 0.22) |
| Right hippocampus | −0.23 (−0.36 to −0.09) | 0.64 (0.48 to 0.76) | 0.54 (0.02 to 0.77) | −0.22 (−0.36 to −0.09) | −0.34 (−0.62 to −0.07) |
| Left hippocampus | −0.13 (−0.26 to 0.01) | 0.56 (0.37 to 0.70) | 0.64 (0.21 to 0.81) | −0.13 (−0.27 to 0.01) | −0.27 (−0.51 to −0.04) |
CI = confidence interval; DZ = dizygotic; MZ = monozygotic.
↵* For schizophrenia the cross-twin correlation (SZtw1–SZtw2) is constrained to be 0.92 in MZ twins and 0.515 in DZ twins based on the genetic point estimates (h2 = 0.81, χ2 = 0.11, e2 = 0.08) of meta-analysis results, and the thresholds on the liabilities are fixed to reflect a prevalence of 1%.