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SCNT cloning (somatic cell nuclear transfer) is a laboratory technique in which the nucleus of an egg cell is replaced with the nucleus of a somatic (body) cell from a donor, producing a zygote that carries the donor’s nuclear DNA. It is the method behind Dolly the sheep, and it is a different thing from gene (molecular) cloning, which copies a DNA fragment rather than an organism or embryo.
Definition and scope
The National Society of Genetic Counselors (NSGC) defines SCNT as “replacing the nucleus of an egg cell with the nucleus of a somatic cell from a donor,” giving a zygote whose nuclear DNA comes from the somatic cell donor. The National Human Genome Research Institute (NHGRI) describes the starting point in the same terms: researchers remove a mature somatic cell, such as a skin cell, from an animal they wish to copy, and move that cell’s genetic material into an egg.
Two different goals sit under the same technique. NHGRI separates them: reproductive cloning produces copies of whole animals, while therapeutic cloning produces embryonic stem cells for experiments. The technique is the same; the purpose, the oversight and the ethical questions are not.
How SCNT is used in practice
The best-documented outcome is reproductive cloning in animals. NHGRI describes Dolly as a lamb produced from the udder cell of a 6-year-old sheep, after hundreds of attempts, and notes that she died at six, about half the average sheep’s 12-year lifespan. NHGRI calls reproductive cloning “a very inefficient technique” and identifies the low efficiency and safety concerns as a serious obstacle.
In agriculture, the U.S. Food and Drug Administration (FDA) has addressed the food-safety question for cloned livestock. Its animal cloning page states that meat and milk from cow, pig and goat clones, and from the offspring of any animal clones, are as safe as the food we eat every day, a conclusion drawn from its final risk assessment of January 2008.
SCNT and related terms
Most confusion on this topic comes from the word “cloning” covering several unrelated things. The comparison below separates the four terms most often confused.
| Term | What it means | Source |
|---|---|---|
| SCNT | An egg’s nucleus is replaced with a somatic cell nucleus, giving a zygote with the donor’s nuclear DNA. | NSGC position statement |
| Reproductive cloning | Produces copies of whole animals; described as very inefficient. | NHGRI Cloning Fact Sheet |
| Therapeutic cloning | Produces embryonic stem cells for experiments. | NHGRI Cloning Fact Sheet |
| Gene (molecular) cloning | A bench technique for copying DNA fragments; not SCNT. See the CASRAI guide on gene cloning. | CASRAI guide |
Where it matters for labs and clinics
Because SCNT involves human or animal eggs and donor cells, the practical questions for laboratory and clinical staff are about consent and oversight rather than reagents. The NSGC position statement (adopted 2014, reaffirmed 2018) draws these lines:
- It opposes SCNT for reproductive purposes, citing ethical concerns and animal evidence of reduced reproductive success and lifespan.
- It supports human-DNA SCNT only where the technique “offers unique potential for therapy or research.”
- It calls for informed consent from both egg donors and DNA donors.
Work that uses SCNT-derived or embryonic stem cell lines also falls under research-ethics and funding rules; CASRAI’s guide to the ethics of embryonic stem cell research covers that policy landscape, and the guide on germline editing legal status by country covers a neighbouring area where national rules differ. For the wider field, see what is biotechnology and what is molecular biology.
A quick checklist for reading a “cloning” claim
- Is an egg’s nucleus being replaced with a somatic nucleus? If yes, it is SCNT; if DNA fragments are being copied in a vector, it is gene cloning.
- Is the stated product a whole animal (reproductive) or embryonic stem cells (therapeutic)?
- For human material, is there documented informed consent from both the egg donor and the DNA donor?
- If efficiency is claimed, how does it compare with Dolly’s hundreds of attempts for one live lamb?
Common misunderstandings
- “Cloning” always means SCNT. It does not; molecular cloning of genes is a routine lab method unrelated to producing embryos.
- SCNT is efficient. NHGRI describes reproductive cloning as very inefficient, and Dolly lived about half a normal sheep’s lifespan.
- Therapeutic and reproductive cloning are the same activity. They share a technique but have different products, and the NSGC position treats them differently.
- Cloned-animal food is untested. The FDA’s January 2008 risk assessment addressed meat and milk from cow, pig and goat clones and their offspring.
Frequently asked questions
What is SCNT cloning?
Somatic cell nuclear transfer replaces the nucleus of an egg cell with the nucleus of a somatic cell from a donor, creating a zygote with the donor’s nuclear DNA (NSGC).
Is SCNT the same as gene cloning?
No. NHGRI distinguishes gene cloning, which copies genes or segments of DNA, from reproductive cloning, which copies whole animals, and therapeutic cloning, which produces embryonic stem cells for experiments.
How efficient is SCNT?
NHGRI calls reproductive cloning very inefficient: Dolly was the only live birth from 277 cloned embryos.
Is meat and milk from cloned animals safe?
The FDA concluded, in a final risk assessment issued in January 2008, that meat and milk from cow, pig and goat clones and the offspring of any animal clones are as safe as the food we eat every day.
Sources
All sources checked 2026-10-29.
- National Human Genome Research Institute, Cloning Fact Sheet: https://www.genome.gov/about-genomics/fact-sheets/Cloning-Fact-Sheet
- National Society of Genetic Counselors, position statement “Human Cloning by Somatic Cell Nuclear Transfer (SCNT) for Reproductive or Therapeutic Purposes” (4.23.2018): https://www.nsgc.org/POLICY/Position-Statements/Position-Statements/Post/human-cloning-by-somatic-cell-nuclear-transfer-scnt-for-reproductive-or-therapeutic-purposes
- U.S. Food and Drug Administration, Animal Cloning: https://www.fda.gov/animal-veterinary/safety-health/animal-cloning
