Gene editing in a human embryo

Why in news?

A Chinese researcher recently made a claim that he had altered the genes of a human embryo that eventually resulted in the birth of twin girls.

What is the technology behind?

• Genes contain the bio-information that defines any individual.
• The information encoded in the genetic material can be attributed to –

1. Height, skin or hair colour
2. Intelligence or eyesight
3. Susceptibility to certain diseases
4. Behavioural traits

• CRISPR (short for Clustered Regularly Interspaced Short Palindromic Repeats) technology is a relatively new, and the most efficient tool for gene “editing” developed in the last one decade.
• The technology replicates a natural defence mechanism in bacteria to fight virus attacks, using a special protein called Cas9.
• The specific location of the genetic codes that need to be changed is identified on the DNA strand.
• Using the Cas9 protein, which acts like a pair of scissors, the specified location is cut off from the strand.
• A DNA strand, when broken, has a natural tendency to repair itself.
• Scientists intervene during this auto-repair process, supplying the desired sequence of genetic codes that binds itself with the broken DNA strand.

How useful it has been so far?

• CRISPR-Cas9 is a simple, effective, and incredibly precise technology.
• The most promising use of the CRISPR technology is in treatment of diseases.
• For example, in sickle cell anaemia, a single gene mutation makes the blood sickle-shaped, which can be reversed using gene editing technology.
• In the case of the new-born Chinese babies, the genes were “edited” to ensure that they do not get infected with HIV.
• However, leading scientists in the field have for long been calling for a “global pause” on clinical applications of the technology in human beings, until internationally accepted protocols are developed.

What is the ethical dilemma involved?

• Verification - Tampering with the genetic material can have unintended and unknown consequences.
• The scientific community has no way to verify the claims on whether the gene editing was carried out in the proper manner.
• Precision - There is a possibility that some other genes also get targeted, resulting in unintended impacts.
• Approval - In most countries of the world, such experiments are banned and are punishable by law.
• Without regulatory approvals, there will be data and information gaps about the experiments on gene editing.
• Consequence - The recent research has edited the genes of an embryo, which would be passed on to the offspring and make changes in the genome of the next generation.
• Thus there is a possibility to produce designer babies with very specific traits in the future.

Source: Indian Express