Devangshu Datta: For a 'brave new world'

The outcomes of a recent experiment with a technique to edit human DNA could go a long way beyond fixing genetic disorders

Many inherited disorders are caused by a single disordered gene and if that was replaced by a healthy version, a miraculous cure might occur. This science fiction trope is edging closer to reality. A 16-person Chinese research team from Sun Yat-Sen University, Guangzhou, recently experimented with a new technology to edit human DNA.

The mere conduct of such an experiment raises disturbing questions about the moral and ethical implications of editing human DNA. To their credit, the Chinese team flagged many of those questions.

The team tried to "edit out" the disorder, beta-thalassemia, in 86 embryos sourced from an in vitro fertilisation clinic. The embryos had been rejected as abnormal. The fertilisation process had gone wrong and these embryos could never come to term. Scientists everywhere commonly use such embryo rejects for experiments.

Beta-thalassemia affects one in every 100,000 people. It is caused by mutations that cause malfunction in the haemoglobin beta protein (HBB) on Chromosome 11. The victim has problems manufacturing haemoglobin, the oxygen-carrier. Victims are prone to anaemia, asthma, heart disease and so on. In its severe form, it is lethal. It can only be countered by bone marrow transplants and repeated blood transfusions.

The researchers used a technique called CRISPR-Cas9 (Clustered regularly interspaced short palindromic repeats-Crispr associated protein 9). CRISPR consists of repeated DNA sequences. It is literally an anti-virus database. those sequences have been classified and memorised as "dangerous" and characteristic of viruses. When such a sequence is seen, it is attacked and excised. The Cas-9 protein is used as a cutting tool to excise the sequence.

CRISPR can be "trained" to memorise new DNA sequences, which will then be treated as dangerous. The Chinese team tried to target the beta-thalassemia disordered HBB gene, using Cas-9 to cut it out and replace it with a normal gene.

However, this did not happen to be reliable. Sometimes, the genome repaired itself using the old mutated gene. Sometimes, other mutations occurred. It worked only 28 times and some of those were partial repairs. The team leader, Junjiu Huang, said that the error rates were way too high and the CRISPR technique was too immature.

However, it is likely that CRISPR will become more reliable. In that case, it could be used to edit out many other single gene disorders, such as cystic fibrosis, sickle cell anaemia and so on. If such a genetic alteration is permanent, it could be passed onto descendants down what is called the "germline". There are huge risks - a botched job could introduce new genetic disorders rather than curing existing ones.

The outcomes could go a long way beyond editing out genetic disorders. The sky might be the limit in terms of finding ways to create immunity to various diseases and conditions. Such a technique could also be used to create designer children. Parents and regimes could end up "shopping" for desirable traits, be it intelligence, appearance, sporting ability and so on.

Even transgenic splicing may be contemplated. Such experiments have been carried out on plants and animals already, including on large mammals. It would be naive to expect that these techniques would not be applied to human DNA sooner or later.

In March (the Chinese paper was released in April), a group of scientists called for a global moratorium on the use of such techniques on human DNA to create inheritable characteristics. Jennifer Doudna, who is credited as the co-inventor of CRISPR-Cas9, was a lead signatory to that paper, which asks that the technique should be better understood before being used on human DNA.

Such a "moral ban" is unenforceable. A 2014 study by the University of Hokkaido surveyed 39 countries and found many grey areas. In India, China and Japan itself, there are guidelines rather than laws.

In any event, the basic science, and lab techniques, are well-known. There may be similar experiments going on in many places. It is unlikely that this could be stopped. As readers of the Aldous Huxley classic would realise, CRISPR-Cas9 could be instrumental in creating a "Brave New World".