Restriction Fragment Length Polymorphism

November 12, 2012

Restriction Fragment Length Polymorphism

Restriction fragment length polymorphism is the process of identifying specific segments of a DNA molecule. It is used to identify potentially defective genes in an individual, or to establish an evidence of a crime or guilt.


During the process of restriction fragment length polymorphism, DNA molecules are isolated from the cells and treated with restriction enzymes. The enzymes cut the DNA at specific points and produces DNA fragments of a certain length. The pieces are separated by the process of electrophoresis, and are identified using specific probes that contain radioactive, complementary nucleotides.

Genetic Disorders

Genetic disorders such as sickle cell disease occur when a single thymine nucleotide is replaced with an adenine. This changes one amino acid in the hemoglobin molecule from valine to glutamic acid. The restricted fragment length polymorphism can identify these changes in the genes associated with sickle cell disease, and help in the diagnosis of the disease. The test can also be used to test the DNA of prospective parents, and to determine how their genes would impact the child. So, if both the parents have a heterozygous gene for sickle cell anemia, there is a 25 percent chance of producing a child with the disease.

Restriction fragment length polymorphism, however, may not be effective in diagnosing diseases that involve changes in more than one gene. It is also ineffective in conforming conditions for which the causative genes have not been identified.

RFLP Markers

The presence of absence of restriction fragment length polymorphism can be used counsel people about their risk of transmitting or developing a disease. However, the RFLP genes may also be associated with mutated genes. Hence, it is important to test the patients as well as their family members to get a clear picture of the disease. It will also help understand the inheritance of the disease over different generations. If the parents decide to have another child, they may decide to undergo the test again to understand the chances of the second child to get the disease.

DNA Typing

While some genes out of the 6 x 109 base pairs of normal DNA are used to make proteins, others do not code for anything. These segments of DNA may undergo mutations. In fact, no two humans have completely identical DNA, unless you take the samples from identical twins. Analysis of the genes can be conducted using restricted fragment length polymorphism. The procedure is known as DNA typing, and is used for paternity testing and for identifying criminals and rapists.


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