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Genetic Disorders
Genetic Disorders - Types
Types of Genetic Disorders
There are four different types of genetic disorders namely single-gene, multifactorial, chromosomal, and mitochondrial. You can see these in detail as under:
This is also known as monogenetic inheritance or Mendelian. This type of genetic disorder occurs when there are mutations or changes in the DNA series of a single gene. Some of the disorders caused by this type of single-gene inheritance include sickle cell anemia, cystic fibrosis, hemochromatosis, Huntington’s disease, and Marfan’s syndrome. These are inherited disorders found in patterns like X-linked, autosomal dominant, and autosomal recessive.
- Multifactorial Inheritance:
This is also known as polygenic or complex inheritance. These types of genetic disorders are caused either by multiple gene mutations or because of environmental factors. For example, in the case of breast cancer, the genes that influence this disease are more susceptible on chromosome numbers 6, 11, 13, 14, 15, 17, and 22. Some classic examples of diseases caused by multifactorial inheritance disorders include high blood pressure, heart disease, Alzheimer’s disease, obesity, diabetes, arthritis, and cancer.
Chromosomes are defined structures comprising of protein and DNA which are found in the individual cell nucleuses. Chromosomes are responsible for carrying genetic material, and therefore abnormalities in their structure or number may result in different types of diseases. Problems in cell division usually results in chromosomal abnormalities. A good example of a chromosomal abnormality can be seen in Down’s syndrome where an affected individual has three sets of chromosome 21. Similarly, some of the other disorders caused by chromosomal inheritance include Klinefelter syndrome, Turner syndrome, and Cri Du Chat (cry of the cat) Syndrome.
- Mitochondrial Inheritance:
When the non-chromosomal DNA of the mitochondria undergoes mutations, it results in this type of genetic disorder. Mitochondria are rod-like or small round organelles that are a part of cellular respiration and are located in the cytoplasm of animal and plant cells. Each mitochondrion contains 5-10 circular DNA pieces. This kind of DNA is always inherited from the mother. Some of the genetic disorders caused by mitochondrial inheritance include myoclonus epilepsy with Ragged Red Fibers (MERRF), an eye disorder called Leber's hereditary optic atrophy, and a type of dementia known as mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS).
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