The other way to deliver genes is an ICSI (Intra-cytoplasmic sperminjection) microinjection method used to make an absorbent in the form of a very thin needle operate in an electroportioned manner, where they insert the genetic material into the cytoplasm or nucleus and the most ideal way is to use viruses as vectors in gene transfer. There are two types of viruses, one DNA and the other RNA type and there are chemical variations between the two viruses, both are made up of units of nucleotides, in addition to the sequence of precise nitrogen rules. Most RNA viruses are not suitable for gene therapy since RNA cannot be associated with the DNA of human cells, except for retroviruses where viruses can convert RNA into DNA. This shows, therefore, that understanding the molecular biology of a cell and how genes work could make an important difference in molecular medicine. Therefore, genetics is more relevant to medicine than classical genetics, which is based only on observable outcomes of reproduction