When she was just three months old, Kirthana Balachandran was diagnosed with beta thalassaemia, a blood diseaseAn illness or sickness. that leaves people tired, weak and short of breath. Every three to five weeks she has to inject blood.

But now a miracle cure might be at hand. Britain's NHSThe National Health Service, the publicly funded healthcare system in the UK. The NHS was founded in 1948. has approved the first geneA gene is the basic unit of heredity.-editing treatment. The health service's chief executive Amanda Pritchard calls it "a historic moment".

Gene therapy removes the genetic problem that causes illnesses. The first successful approach, gene addition, sees doctors place a new gene into cells to fight a disease.

Gene editing is more complex. The new technique, called CRISPRCRISPR-Cas9 allows scientists to remove, add or alter sections of DNA with ease and simplicity. ,¹ involves using molecular-sized scissors to alter existing DNADeoxyribonucleic acid is the material in an organism that carries genetic information.. It could, for instance, turn on a gene that does not work, or turn off one that is working incorrectly.

For thalassaemia, the stem cellsUnspecialised cells that have the ability to develop into different types of cell. that do not work are extracted and altered.²

This process has already succeeded. Abdul-Qadeer Akhtar took part in clinical trialsStudies by experts that test whether a new medicine or treatment works and is safe.. He said: "My overall health and quality of life have significantlyGreatly or very importantly. improved. I'm eager to embrace life to the fullest."

But gene therapy raises some moral problems. It comes with an enormous price tag. One treatment typically costs around £1.6m.³ A two-tier system could develop, where only the richest can benefit.

Removing disease is one thing. But what if you alter genetics to make people "better"? It could enable a new generation of eugenicsThe idea that human beings should be improved through genetic engineering. In the past, eugenics has generally involved killing people who are deemed "inferior"..⁴ The super-rich could edit their babies to make them stronger and smarter than others.

Some fear scientists could tamperto make changes that you shouldn't be making with genes to create super-soldiers who run on four hours of sleep, barely feel pain and have immense physical strength. This can be achieved with current technology. Expert Fyodor Urnov says: "You don't need a large lab operation. You just need the ill will."

Is this a dangerous path?

Yes: It can achieve some good in the short term. But it is a very slippery slope. Soon we could have genetic super soldiers, designer babies and design-your-own child schemes. This is against nature.

No: Scientists have always been capable of doing evil things. But laws and public pressure stop them doing their worst. There is no reason things will be any different with gene editing.

Or... There are always risks, but the work being done now is mostly good. But new dangers are always possible. We should take care to make sure that genetic surgery is monitored.

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