Table. Autism Spectrum Disorder Heritability Model Comparisons and Parameter Estimates.
| Modelsb | Model Comparison Measures | Estimated Variance (95% CI)a | |||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of Model Parameters | −2LL | Diff − 2LL |
P Valuec | Additive Genetic (Narrow-Sense Heritability) | Nonadditive Genetic | Environment | Total Genetic (Broad-Sense Heritability) | ||
| Shared | Nonshared | ||||||||
| ACDE | 14 | 146 836 | NA | NA | 0.69 (0.40-0.86) | 0.10 (0.00-0.38) | 0.04 (0.00-0.14) | 0.16 (0.05-0.30) | 0.80 (0.59-0.95) |
| ACE | 13 | 146 836 | 0.4 | .52 | 0.77 (0.58-0.87) | NA | 0.03 (0.00-0.13) | 0.20 (0.13-0.30) | 0.77 (0.58-0.87) |
| ADE | 13 | 146 836 | 0.8 | .38 | 0.80 (0.68-0.87) | 0.05 (0.00-0.26) | NA | 0.15 (0.05-0.21) | 0.85 (0.79-0.95) |
| CDE | 13 | 146 856 | 20.9 | <.001 | NA | 0.64 (0.48-0.75) | 0.25 (0.21-0.29) | 0.11 (0.03-0.24) | 0.64 (0.48-0.75) |
| AE | 12 | 146 836 | 0.9 | .64 | 0.83 (0.79-0.87) | NA | NA | 0.17 (0.13-0.21) | 0.83 (0.79-0.87) |
| DE | 12 | 147 100 | 264 | <.001 | NA | 0.99 (0.97-1.00) | NA | 0.01 (0.00-0.03) | 0.99 (0.97-1.00) |
| CE | 12 | 146 897 | 61 | <.001 | NA | NA | 0.39 (0.37-0.41) | 0.61 (0.59-0.63) | NA |
| E | 11 | 147 996 | 1160 | <.001 | NA | NA | NA | 1.00 (1.00-1.00) | NA |
Abbreviations: 2LL, 2 × logarithm of the likelihood; Diff − 2LL, 2 × difference in log-likelihood between the model and the full model; NA, not applicable.
The 95% CIs are 2-sided CIs. Variances are based on the tetrachoric correlations. The unadjusted tetrachoric correlation (SD) was estimated to 0.87 (0.08) and 0.40 (0.10) for monozygotic and dizygotic twins; 0.41 (0.01) for full siblings; 0.22 (0.03) and 0.17 (0.04) for maternal and paternal half siblings.
All models adjusted for sex and birth cohort. The genetic terms for each model are shown in each row, which include additive genetic effect (A; inherited additive effects of different alleles), shared environmental factors (C; nongenetic influences contributing to similarity within sibling pairs), nonadditive (dominant) genetic factors (D; interaction effects between alleles at the same locus), and nonshared environmental factors (E; making siblings dissimilar).
P value for testing the hypothesis: the parameters not in the model but in the full model are all equal to 0.