JK SCIENCE Vol. 8 No. 3, July-September 2006 125 REVIEW ARTICLE From the Department of Forensic Medicine & Toxicology, K.M.C., Manglore & *Manipal, **Deptt. of Microbiology & ***Forensic Medicine & Toxicology, HIMS, Dehradun India. Correspondence to : Dr. Tanuj Kanchan, Deptt. of Forensic Medicine & Toxicology, Kasturba Medical College, Manglore, India. Multifaceted Aspects of Human Cloning Tanuj Kanchan, T. S. Mohan Kumar*, Ashish Kumar**, Sanjoy Das*** Introduction Curious human brain has led to numerous discoveries. Human cloning, which was a topic of science fiction for hundreds of years, turned real with arrival of Dolly, a cloned sheep in 1997. Cloning since its inception has led to seemingly unending and controversial debate worldwide on a number of medico legal, ethical and social issues (1,2). The present review discusses all these aspects of human cloning. What is cloning ? Clone means one or a group of genetically identical cells, organisms or plants derived by vegetative reproduction from a single parent; also, a DNA population, derived from a single hybrid DNA molecule by replication in a eukaryotic or bacterial host cell (3). The word "clone" is derived from a Greek word for taking a cutting from a plant. Scientists traditionally used the term "cloning" to describe different processes for duplicating biological material. In simple terms, human cloning is a process of producing genetically identical human beings. In general biological terms, human cloning is defined as "the asexual replication of an existing genome or individual, or a replica of a DNA sequence, such as a gene, produced by genetic engineering". Historical Milestones First report of successful cloning of lambs (4) that went unnoticed was soon followed by arrival of "Dolly" in 1997 (5). Ian Wilmut and colleagues at Roslin Institute and PPL therapeutics near Edinburgh produced the clone, Dolly the lamb. Dolly was created by taking cells from the udder of an ewe and "reprogramming" them to create a new embryo by a process known as nuclear transfer, and implanting the embryo in another ewe. Doubts related to Dolly's origin that if she was really a clone was put to rest by Forensic DNA testing methods, which confirmed Dolly to be the direct descendent of an Udder cell (6,7). Soon there were reports of cloned mice and large farm animals. Genetically altered fibroblasts were used to clone large farm animals, sheep (8) and cow (9) by nuclear transfer. Cloning of human embryos has already been achieved but successful cloning of humans has not been proven yet despite of some claims regarding the same. The South Korean scientists announced the cloning of a human embryo first in February 2004. They grew the embryo for seven days before destroying it. Recently, South Korean scientists have created the world's first cloned dog Snuppy (10). Reproductive and Therapeutic Cloning Technologies 1. Reproductive Cloning Technology includes a process called "somatic cell nuclear transfer" (SCNT). The genetic material from the nucleus of a donor adult cell is transferred to an egg whose nucleus, and thus its genetic material has been removed. The reconstructed egg containing the DNA from a donor cell is treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth. Thus, reproductive cloning is a process of nuclear transplantation and embryo splitting. Dolly was created by reproductive cloning technology. 2. Therapeutic Cloning Technology also known as, "embryo cloning," is the production of human embryos for use in research with the goal of harvesting stem cells that can be used to study human development and treat diseases. Stem cells are extracted from the egg at blastocyst stage and can be used to generate any type of specialized cell in the human body.