Thanks to recent technological advances, traditional twin-based heritability estimates can be supplemented with estimates of heritability captured by common genetic variants, referred to as SNP-based heritability.
However, the traditional concept of heritability, which may be more appropriately called the genetic heritability, represents only the percentage of phenotypic variance due to additive genetic effects.
In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample.
Although traditional estimates of heritability for epilepsy vary greatly, depending on the method used, the population sampled and the mixture of clinical subtypes considered, studies have consistently demonstrated that the condition has a substantial genetic component; estimates of heritability from twin studies typically fall in the range 25 70% (Miller et al., 1998; Kjeldsen et al., 2001).
Although it is generally preferred to use the traditional parameters such as heritability and genotype-relative-risk (GRR) [42] to characterize experimental scenarios, we propose using accuracy as an indicator parameter to capture the characteristics of an ascertained population.
Recently mixed linear models are used to address the issue of "missing" heritability in traditional Genome-wide association studies (GWAS).
Genetic methodologies are quite diverse across studies, and include traditional twin studies of heritability, association analysis, analysis of telomere length, copy number variation (CNV), and the effects of early environmental experiences on the neurobiology of disease and behavior.
In addition, using a smaller set of these landmarks, we explored the heritability of more traditional distance-based facial traits.
The realized relationship matrix in a classical mixed linear model makes it possible to obtain more accurate and reliable estimates for the narrow sense heritability, compared to traditional pedigree-based analysis [ 19, 20].
However, it is difficult to make appreciable genetic progress by traditional breeding methods because the heritability of the trait is low (Heringstad et al. 2000; Hansen et al. 2002; Carlén et al. 2004) and there is unfavourable genetic correlation with production traits (Lund et al. 1999; Carlén et al. 2004).
