- Patient Comments: Genetic Disease - Symptoms
- Patient Comments: Genetic Disease - Screening
- Patient Comments: Genetic Disease - Personal Experience
Multifactorial inheritance, which is also called complex or polygenic inheritance. Multifactorial inheritance disorders are caused by a combination of environmental factors and mutations in multiple genes. For example, different genes that influencebreast cancer susceptibility have been found on chromosomes 6, 11, 13, 14, 15, 17, and 22. Some common chronic diseases are multifactorial disorders.
Examples of multifactorial inheritance include:
Multifactorial inheritance also is associated with heritable traits such as fingerprint patterns, height, eye color, and skin color.
Chromosomes, distinct structures made up of DNA and protein, are located in the nucleus of each cell. Because chromosomes are the carriers of the genetic material, abnormalities in chromosome number or structure can result in disease. Abnormalities in chromosomes typically occur due to a problem with cell division.
For example, Down syndrome (sometimes referred to as "Down's syndrome") or trisomy 21 is a common disorder that occurs when a person has three copies of chromosome 21. There are many other chromosome abnormalities including:
- Turner syndrome (45,X0),
- Klinefelter syndrome (47, XXY), and
- Cri du chat syndrome, or the "cry of the cat" syndrome (46, XX or XY, 5p-).
Diseases may also occur because of chromosomal translocation in which portions of two chromosomes are exchanged.