In Switzerland, all newborns receive prenatal screening for phenylketonuclear syndrome or PKU. It is a genetic disease that affects the metabolism, caused by a malfunction of the enzyme phenylalanine hydroxylase. The team of Professor Gerald Schwank used CRISPR / Cas9 for the first time to correct mutated genes. For the time being the procedure has been applied only to animal models and has been completely successful.
PKU causes the progressive accumulation of phenylalanine in tissues, damaging neurons and causing mental retardation. Researchers used genetic editing to transfer the correct genetic code into liver cells. Thanks to the procedure, they modified about 60% of the abnormal copies of the gene and stimulated the production of the missing enzyme first. As a result, phenylalanine dropped to normal levels and most of the symptoms disappeared.
The procedure used is slightly different from the traditional one and is also much more efficient. The attempts made with the traditional version of CRISPR have indeed failed. The procedures had been able to correct only low percentages of cells. As a result, the effects on the guinea pigs had been very mild.
For the study in question, the scientists used adeno-associated viruses to carry the correct DNA. They injected them into the blood of guinea pigs, in order to infect the liver cells and introduce the new genes. This same method could also be useful in other metabolic diseases, even if it is still to be explored. According to Professor Gerald Schwank, the possible risks are reduced. Before moving on to human experimentation, it will still be necessary to switch from other animal models.