GENE EDITING

GENE EDITING

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A Chinese scientist made the world’s first gene edited babies.

About

• A Chinese scientist, He Jiankui, used the CRISPR–Cas9 gene editing technique in the twin girls to disable a gene called CCR5. This gene encodes a protein that allows HIV to enter and infect cells.

• Disabling the CCR5 gene will make the babies resistant to HIV infection.

Can Disabling the CCR5 Gene Prevent HIV?

• While it is generally believed that babies without a functional CCR5 gene will become resistant to HIV infection, certain other strains of HIV use another protein (CXCR4) to infect cells.

• Even people who are born with two copies of the nonfunctional CCR5 gene are not completely protected or resistant against HIV infection.

• There is also the possibility that the gene editing tool could have caused unintended mutations in other parts of the genome, which may lead to unpredictable health consequences.

CRISPR-Cas9

• CRISPR-Cas9 is a recent approach to genome editing, which is short for clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9.

• It was adapted from a naturally occurring genome editing system in bacteria.

• It is faster, cheaper, more accurate, and more efficient than other existing genome editing methods.

• CRISPR is the DNA-targeting part of the system which consists of an RNA molecule, or ‘guide’, designed to bind to specific DNA bases through complementary base-pairing.

• Cas9 is the nuclease part that cuts the DNA.

Ethical Issues with Gene Editing

• Safety: Due to the possibility of off-target effects (edits in the wrong place) and mosaicism (when some cells carry the edit but others do not), safety is of primary concern.

• Informed consent: In case of emryos, it is impossible to obtain informed consent for germline therapy; worries about the possibility of obtaining truly informed consent from prospective parents as long as the risks of germline therapy are unknown.

• Justice and Equity: There is concern that genome editing will only be accessible to the wealthy and will increase existing disparities in access to health care and other interventions. Some worry that taken to its extreme, germline editing could create classes of individuals defined by the quality of their engineered genome.

• Genome-Editing Research Involving Embryos: Many people have moral and religious objections to the use of human embryos for research. Public funds cannot be used for any research that creates or destroys embryos.

• Against order of nature: Creating children with preferred traits raises bio-ethical concerns as it goes against natural process

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