World’s first gene-editing therapy saves a baby with rare disorder: Why is this significant?
In a breakthrough that can heal babies born with rare diseases, US doctors and researchers have successfully tested a gene-editing therapy moulded specifically to target the errors in an infant’s genetic code.
Within days of being born, the now nine-month old KJ started experiencing lethargy and difficulty breathing. He was diagnosed with a genetic metabolic disorder called carbamoyl phosphate synthetase 1 (CPS-1) deficiency. With his body struggling to get rid of ammonia, the doctors thought he would need a liver transplant. But after receiving infusions of the therapy designed for him, KJ has been eating proteins like a normal baby. The dose of the medicines he needed to control ammonia levels has reduced, and he is gaining weight.
“We’ve been in the thick of this since KJ was born, and our whole world’s been revolving around this little guy and his stay in the hospital. We’re so excited to be able to finally be together at home so that KJ can be with his siblings, and we can finally take a deep breath,” his father Kyle Muldoon said in a release.
What is the condition that baby KJ has?
CPS-1 deficiency is a urea cycle disorder. Dietary protein is broken down by the body to release ammonia. Normally, our body converts this excess ammonia to urea and removes it from the body through urination. However, children with urea cycle disorders lack the enzyme in the liver that converts the ammonia to urea. This leads to a build-up of ammonia in the body, which can damage organs.
A liver transplant can help get the urea cycle restarted in these children. The doctors, however, have to wait till the child grows enough to be able to undergo transplantation. In the meantime, episodes of high ammonia build-up could damage their organs, including irreversible brain injury and even death. CPS-1 deficiency has an estimated mortality of 50% in early infancy.
Once the doctors diagnosed him, he was put on a protein-restricted diet and medications to control the ammonia levels in the body.
What did the researchers do?
KJ’s was a condition that could be treated by very precisely changing the erroneous letter in his genetic code. For this, they used CRISPR, which is an immune system used by microbes to find and eliminate unwanted invaders. But in therapies, CRISPR can be used to make your body’s cells attack toxic cells or regenerate beneficial cells. The CRISPR-based scissors could sift through KJ’s genetic code, exactly identify the mistake, and correct it. They then wrapped this up in a lipid molecule to protect it from damage till it reached the liver where it could do the corrective work.
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The researchers conducted animal testing on the product they named k-abe. When KJ was six months old, the researchers sought permission from the US Food and Drug Administration to give him the medicine, which was approved. He received his first infusion in February, followed by doses in March and April as well.
After the infusions, he did have two viral infections accompanied by vomiting and diarrhoea but his ammonia levels did not shoot up. He did not suffer any serious side effects. The doctors were able to increase the proteins in his diet and halve the dose of the medicines he needed to remove excess ammonia. He was able to start gaining weight.
© The Indian Express Pvt Ltd
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