What are Some Benefits of Cloning?

Functional cloning is to use the information of biochemical functions such as protein defects caused by the genetic damage known to the disease to perform gene mapping, and then clone the disease-causing gene. Most of the gene cloning that has been performed is to detect the protein encoding the disease gene in advance, use its mRNA to reverse transcribe into cDNA, and then use cDNA as a probe to "fish" the gene itself from the human genome. However, the gene products of most genetic diseases are unknown, and gene cloning cannot be performed by functional cloning strategies.