Cloning Fact Sheet

Overview

• Cloning refers to processes used to create genetically identical copies of a biological entity.
• Clones include genes, cells, tissues, and whole organisms like sheep.

Natural Cloning

• Some plants and single-celled organisms reproduce asexually, producing identical offspring.
• Identical twins in humans and mammals result from a fertilized egg splitting, forming embryos with nearly identical DNA.

Types of Artificial Cloning

• Gene Cloning: Produces copies of genes or DNA segments.
• Reproductive Cloning: Produces copies of whole animals.
• Therapeutic Cloning: Produces embryonic stem cells for research on disease treatment.

Cloning Research at NHGRI

• Primarily involves gene cloning.
• NHGRI does not engage in cloning of mammals or humans.

Gene Cloning Process

• Involves inserting a gene into a vector, which is then induced to multiply, copying the gene.

Animal Cloning Process

• DNA from a somatic cell is transferred to an egg cell with removed nucleus.
• The process involves developing the egg into an embryo and implanting it in a surrogate.
• Example: Dolly the sheep.

Cloned Animals

• Various animals like mice, cows, sheep, and chickens have been cloned.
• Dolly was the first mammal cloned from an adult somatic cell.
• Other cloned mammals include cats, deer, dogs, horses, and more.

Human Cloning

• No confirmed evidence of human cloning.
• Technical challenges due to spindle proteins necessary for cell division in primates.

Appearance of Clones

• Clones may not look identical due to environmental factors.
• Example: Cc, the first cloned cat, had a different appearance than its genetic donor.

Applications of Cloned Animals

• Potential benefits in medicine and agriculture.
• Cloning endangered species or producing animals with desirable traits.
• FDA has approved cloned animal products as safe.

Drawbacks of Cloning Animals

• Low efficiency and health issues in cloned animals such as organ defects and premature aging.
• Shorter telomeres in clones can lead to shortened lifespans.

Therapeutic Cloning

• Used to create embryonic stem cells for research on diseases.
• Involves destruction of embryo in test tube.

Applications of Therapeutic Cloning

• Growing healthy tissues to replace injured or diseased ones.
• Studying molecular causes of disease and testing drugs.

Drawbacks of Therapeutic Cloning

• Potential cells could develop into cancer due to mutations after many cell divisions.

Ethical Issues in Cloning

• Reproductive cloning raises concerns about human identity and dignity.
• Therapeutic cloning involves destruction of embryos, raising moral questions.

Conclusion

• Cloning remains a field with significant scientific interest and ethical debate.

Note: Last updated on August 15, 2020.