Contribution of genetic and environmental variance components to mutagen sensitivity
| . | Bleomycin . | . | BPDE . | . | γ-Radiation . | . | 4-NQO . | . | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | Full model* . | No genetic influence . | Full model . | No genetic influence . | Full model . | No genetic influence . | Full model . | No genetic influence . | ||||||||
| Log-likelihood | 199.967 | 194.664 | 206.199 | 201.101 | 491.806 | 487.430 | 237.290 | 230.99 | ||||||||
| χ2 | 10.606 | 10.195 | 8.750 | 12.60 | ||||||||||||
| P (two sided) | <0.01 | <0.01 | <0.01 | <0.01 | ||||||||||||
| Degrees of freedom | 1 | 1 | 1 | 1 | ||||||||||||
| Age coefficient | 0.006 | 0.006 | −0.004 | −0.004 | 0.001 | 0.001 | 0.003 | 0.002 | ||||||||
| Variances | ||||||||||||||||
| Genetic | 0.077 | Fixed | 0.083 | Fixed | 0.0316 | Fixed | 0.077 | Fixed | ||||||||
| Shared | 0.049 | 0.109 | 0.035 | 0.112 | 0.000 | 0.015 | 0.002 | 0.015 | ||||||||
| Nonshared | 0.063 | 0.081 | 0.055 | 0.069 | 0.019 | 0.026 | 0.052 | 0.026 | ||||||||
| Heritability (%) | 40.7 | 48.0 | 62.7 | 58.8 | ||||||||||||
| . | Bleomycin . | . | BPDE . | . | γ-Radiation . | . | 4-NQO . | . | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | Full model* . | No genetic influence . | Full model . | No genetic influence . | Full model . | No genetic influence . | Full model . | No genetic influence . | ||||||||
| Log-likelihood | 199.967 | 194.664 | 206.199 | 201.101 | 491.806 | 487.430 | 237.290 | 230.99 | ||||||||
| χ2 | 10.606 | 10.195 | 8.750 | 12.60 | ||||||||||||
| P (two sided) | <0.01 | <0.01 | <0.01 | <0.01 | ||||||||||||
| Degrees of freedom | 1 | 1 | 1 | 1 | ||||||||||||
| Age coefficient | 0.006 | 0.006 | −0.004 | −0.004 | 0.001 | 0.001 | 0.003 | 0.002 | ||||||||
| Variances | ||||||||||||||||
| Genetic | 0.077 | Fixed | 0.083 | Fixed | 0.0316 | Fixed | 0.077 | Fixed | ||||||||
| Shared | 0.049 | 0.109 | 0.035 | 0.112 | 0.000 | 0.015 | 0.002 | 0.015 | ||||||||
| Nonshared | 0.063 | 0.081 | 0.055 | 0.069 | 0.019 | 0.026 | 0.052 | 0.026 | ||||||||
| Heritability (%) | 40.7 | 48.0 | 62.7 | 58.8 | ||||||||||||
NOTE: The pedigree-based maximum likelihood method (13, 14) was used to quantify the influences of genetic and environmental contributions to mutagen sensitivity.
The full model includes variances due to genetic, nonshared, and shared environmental factors. The pedigree-based maximum likelihood method fitted to the data by specifying age on the mean phenotype (breaks per cell) as a fixed effect and partitioning the total variance by the contribution of genetic influence, shared environment (common environmental factors shared by family members), and nonshared environment (environmental factors unique to each individual subject) to the full model.