The study of the developmental basis for phenotypic variability addresses a higher level of abstraction in that it deals with the tendency of developmental systems to change, amplify, or reduce the expression of genetic variation at the phenotypic level.
To describe the molecular cause of phenotypic variability, cellular events and phenotypic expression must be measured simultaneously at the level of single cells [9], [10].
Understanding the causes and consequences of phenotypic variability is a central topic of evolutionary biology.
Regulatory polymorphisms have emerged as a prevalent source of phenotypic variability, capable of driving rapid evolution.
Indels have a wide range of effects as a very important cause of phenotypic variability.
In this review, we have discussed the neuropathological background of phenotypic variability of FTD.
However, the degree of phenotypic variability that is explained by epigenetic processes still remains unclear.
Heritability is defined as the proportion of phenotypic variability that is explained by inherited genetic variants.
They also highlight that multiple genes can influence patterns of phenotypic variability.
The existence of phenotypic variability for different mutations is also reported for other WWS genes.
