Question: What is the purpose of restriction mapping?

Juan Ortiz answered on 21 Jun 2016:

The genes are responsible for our features, for example one gene can be involved in the eyes colour. A gene can have different versions that are called ALLELES. For example in the case of the gene responsible for our eyes colour, there can be two alleles one for blue eyes and the other for brown eyes. A person with two alleles determining blue eyes will have blue eyes whereas a person with a single brown allele (regardless what is the other one blue or brown) will have brown eyes. However, sometimes the genes determine features that can’t be seen with our bare eyes, because they are in our internal organs or are related to our biochemistry. In these cases, one of the methods used to know which allele or alleles a person has, is the restriction mapping. This technique uses special enzymes called restriction enzymes that only cut the DNA in a specific sequence. So it is possible that one restriction enzyme cuts one of the alleles of a gene and not the other. By looking at the pattern of pieces of DNA of a person it is possible to know which allele or alleles has. And why do we want to know that? If one of the alleles of a gene is responsible of a disease and not the other we can tell if a person is going to be healthy or sick and whether this person can pass this disease on to his/her sons and daughters.

So one of the applications of restriction maps is studying whether someone has an allele responsible of a disease.