Four Types of Genetic Inheritance

By Jonae Fredericks

DNA, or deoxyribonucleic acid, is the genetic code for all human beings. Every cell within the human body contains DNA, made up of four chemicals including adenine, guanine, thymine and cytosine. Every human being inherits DNA from both his parents. Abnormalities within the inherited DNA results in genetic inheritance disorders, of which there are four types.

Monogenetic Inheritance

Also referred to as single-gene genetic disorder, monogenetic inheritance occurs in approximately one of every 200 births, according to the U.S. Department of Energy. Mutations in the sequence of a single gene triggers the genetic disorder, which causes proteins within cellular structures to function improperly. Examples of monogenetic inheritance disorders are Huntington's disease and Marfan syndrome. Cystic fibrosis, a chronic genetic disorder that produces life-threatening lung infections also has links to monogenetic inheritance.

Complex Inheritance

Environmental influences in combination with multiple genetic mutations define disorders that result from complex genetic inheritance. High blood pressure is one example of a disorder linked to complex inheritance. Obesity is another prime example according to the University of Texas. While obesity does have genetic links, overeating --- an environmental influence --- also plays a large role, making the genetic disorder more complex. Skin pigmentation and intelligence quotient (IQ) also belong to the complex inheritance realm.

Chromosomal Abnormalities

Within the core or nucleus of every cell is DNA and protein. Because chromosomes hold genetic material, the slightest abnormality can cause a disorder. The March of Dimes reports that one in every 150 babies born in the U.S. has chromosomal abnormalities that result in physical or mental defects. Trisomy 21 (Down syndrome) is a result of a chromosome 21 abnormality in which the body contains three copies of this chromosome. Turner syndrome is another disorder that affects females, the result of one X chromosome instead of the normal two.

Nonchromosomal DNA Mutations

Nonchromosomal DNA mutations are very rare, affecting the mitochondria. These tiny, rod-shaped organelles are the fuel centers for each cell. The mitochondria turn food into the fuel that cells need to function. The U.S. National Library of Medicine explains that mitochondrial DNA, an inherited DNA from the mother, relies on the normal operation of 37 genes. Mutations in mitochondrial DNA are responsible for genetically inherited hearing loss, cyclic vomiting syndrome and Leber hereditary optic neuropathy, an inherited type of vision loss.

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