Table 3.
ACE models in concordant ASD and TD twin pairs
| A (additive genetics) | C (shared environment) | E (unique environment) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Structure | ASD | CI | p | TD | CI | p | ASD | CI | p | TD | CI | p | ASD | CI | TD | CI |
| Total brain volume | 0.84 | [0.45, 1.14] | <0.001✝ | 0.81 | [0.54, 1.07] | <0.001✝ | – | – | – | – | – | – | 0.16 | [−0.14, 0.55] | 0.19 | [−0.07, 0.46] |
| Cortical GM | 1.00 | [0.77, 1.23] | <0.001✝ | 0.74 | [0.46, 1.03] | <0.001✝ | – | – | – | – | – | – | 0.26 | [−0.23, 0.23] | 0.001 | [−0.03, 0.54] |
| Cortical WM | 0.79 | [0.37, 1.21] | <0.001✝ | 0.93 | [0.75, 1.11] | <0.001✝ | – | – | – | – | – | – | 0.21 | [−0.21, 0.64] | 0.07 | [−0.11, 0.25] |
| Subcortical GM | × | × | × | 0.95 | [0.77, 1.13] | <0.001✝ | – | – | – | – | – | – | × | × | 0.05 | [−0.13, 0.23] |
| Cerebellar GM | × | × | × | 0.92 | [0.73, 1.12] | <0.001✝ | – | – | – | – | – | – | × | × | 0.08 | [−0.12, 0.27] |
| Cerebellar WM | – | – | – | 0.92 | [0.72, 1.12] | <0.001✝ | 0.48 | [0.11, 0.85] | 0.011✝ | – | – | – | 0.52 | [0.15, 0.89] | 0.08 | [−0.12, 0.28] |
| Brainstem | × | × | × | 1.04 | [0.87, 1.21] | <0.001✝ | – | – | – | – | – | – | × | × | −0.04 | [−0.21, 0.13] |
| Ventricles | – | – | – | × | × | × | 0.65 | [0.46, 0.85] | <0.001✝ | – | – | – | 0.35 | [0.15, 0.54] | × | × |
| Total surface area | 0.93 | [0.70, 1.16] | <0.001✝ | × | × | × | – | – | – | – | – | – | 0.07 | [−0.16, 0.30] | × | × |
| Mean thickness | – | – | – | 0.60 | [0.40, 0.80] | <0.001✝ | 0.88 | [0.80, 0.96] | <0.001✝ | – | – | – | 0.12 | [0.04, 0.20] | 0.40 | [0.20, 0.60] |
| Mean curvature | × | × | × | – | – | – | – | – | – | 0.67 | [0.41, 0.92] | <0.001✝ | × | × | 0.33 | [0.08, 0.59] |
The ACE model for broad sense heritability was calculated separately for twin pairs in which both twins were diagnosed with autism spectrum disorder (ASD) or were typically-developing (TD) controls. Twin pairs discordant for ASD were excluded. When A or C was non-significant within the model (−), a constrained AE or CE model was utilized. When model assumptions were violated, model estimates were not generated, but the parameters that would have been most appropriate are indicated (×). Total brain volume = all cortex (cortical gray matter (GM) and white matter (WM) + cerebellar GM/WM + brainstem + ventricles) and Ventricles = lateral + inferior lateral + 3rd + 4th. E estimates were based on the residuals and were not tested for significance. Significant model parameter at *p < 0.05 and ✝False Discovery Rate [73] correction across the estimates within each column are indicated