Quantitative Traits
Polygenic inheritance refers to inheritance of a phenotypic characteristic (trait) that is attributable to two or more genes and can be measured quantitatively. Multifactorial inheritance refers to polygenic inheritance that also includes interactions with the environment. Unlike monogenic traits, polygenic traits do not follow patterns of Mendelian inheritance (separated traits). Instead, their phenotypes typically vary along a continuous gradient depicted by a bell curve.
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An example of a polygenic trait is human skin color. Many genes factor into determining a person's natural skin color, so modifying only one of those genes changes the color only slightly. Many disorders with genetic components are polygenic, including autism, cancer, diabetes and numerous others. Most phenotypic characteristics are the result of the interaction of multiple genes.
Examples of disease processes generally considered to be results of multifactorial etiology:
Congenital malformation
- Cleft palate
- Congenital dislocation of the hip
- Congenital heart defects
- Neural tube defects
- Pyloric stenosis
- Talipes
Adult onset diseases
- Diabetes Mellitus
- Cancer
- Epilepsy
- Glaucoma
- Hypertension
- Ischaemic heart disease
- Manic depression
- Schizophrenia
- Psoriasis
- Thyroid diseases
- Alzheimer's Disease
Multifactorially inherited diseases are said to constitute the majority of genetic disorders affecting humans which will result in hospitalization or special care of some kind.
Read more about this topic: Mapping Of Quantitative Trait Loci
Famous quotes containing the word traits:
“For the myth is the foundation of life; it is the timeless schema, the pious formula into which life flows when it reproduces its traits out of the unconscious.”
—Thomas Mann (1875–1955)