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Polygenic inheritance
Polygenic inheritance occurs when multiple genes are involved in controlling the phenotype of a trait.
The phenotype is an accumulation of contribution by multiple genes.
These traits shows continuous variation and are referred to as quantitative traits. -
Sex-linked traits
Genes located on a sex (X or Y) chromosome. This determines the traits from genes on the X chromosome. For example, the hemophilia trait is found more frequently in makes. Hemophilia is a disease where individuals has a difficult time clotting blood if there’s a cut or bruise. -
Pleiotropy
Pleiotropy refers to an allele which has more than one effect on the phenotype, and multiple symptoms can be traced back to one defective allele. Some of the diseases you can get is Cystic Fibrosis and sickle cell anemia. -
Environmental effects
Allele expression could be affected by the conditions around organisms. For example, temperature can affect the coat colors of arctic foxes and Siamese cats. Phenotypes are also affected by the environmental conditions and conditions and genetics combined. -
Epistasis
Epistasis is the situation whereby 1 gene pair affects the expression of another gene pair. The dominant allele of one gene pair would hide another expression of a different gene pair. -
Real world application
Because of pleiotropy, 30,000 people in the United States has cystic fibrosis, and 70,000 people worldwide has it, according to cff.org. The disease affects the lungs, pancreas, and other vital organs. There are multiple treatments, but there is no cure to the disease.