Definition of Human genetic engineering

Human genetic engineering refers to the controlled modification of the human genome, which is the genome of Homo sapiens, composed of 23 pairs of chromosomes with a total of approximately 3 billion DNA base pairs containing an estimated 30,000 genes. DNA provides the genetic blueprint for all living organisms that influences the physical and mental actions and abilities. With the advent of DNA research and the ability to change gene expressions, it is now possible that scientists may be able to change human capacities, whether they be physical, cognitive, or emotional. Human genetic engineering is still in its infancy, however, with current research generally restricted to animals or gene therapy.
Healthy humans do not need gene therapy to survive (live a socially acceptable lifespan), though it may prove helpful to treat certain diseases. Special gene modification research has been carried out on groups such as the 'bubble children' - those whose immune systems do not protect them from the bacteria and irritants all around them. The first clinical trial of human gene therapy began in 1990, but (as of 2006) is still experimental. Other forms of human genetic engineering are still theoretical, or restricted to fiction stories. Recombinant DNA research is usually performed to study gene expression and various human diseases. Some drastic demonstrations of gene modification have been made with mice and other animals, however; testing on humans is generally considered off-limits. In some instances changes are usually brought about by removing genetic material from one organism and transferring them into another species, method is known as recombinant genetics.