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Human somatic variations are somatic mutations (mutations that occur in somatic cells) both at early stages of development and in adult cells.These variations can lead either to pathogenic phenotypes or not, even if their function in healthy conditions is not completely clear yet.
Neomorphic mutations are a part of the gain-of-function mutations and are characterized by the control of new protein product synthesis. The newly synthesized gene normally contains a novel gene expression or molecular function. The result of the neomorphic mutation is the gene where the mutation occurs has a complete change in function. [56]
One example of oligogenic inheritance is a case where one gene is sufficient to cause a trait, however its penetrance or expressivity is influenced by another gene, called a modifier. An example of such a case is the gene TGFB1 which modified a person's risk of developing Alzheimer's disease if they are carrying the disease variant of the gene ...
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
X-linked recessive inheritance. X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation, see zygosity.
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
If a mutation occurs within a gene, the new allele may affect the trait that the gene controls, altering the phenotype of the organism. [8] However, while this simple correspondence between an allele and a trait works in some cases, most traits are more complex and are controlled by multiple interacting genes within and among organisms.
The study of human genetic variation has evolutionary significance and medical applications. It can help scientists reconstruct and understand patterns of past human migration. In medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in certain population groups.