Researchers correct genetic mutation

The metabolic disorder phenylketonuria delays mental and motor development; if left untreated, it can cause massive mental disabilities. In Switzerland, all newborn babies are screened for this genetic disorder.

The metabolic disorder is caused by a mutation in a gene that provides the blueprint for the enzyme phenylalanine hydroxylase (Pah). This enzyme, which is produced by the cells of the liver, metabolizes phenylalanine. According to the Federal Institute of Technology (ETH) in Zurich, a special diet can reduce a person’s symptoms, but there is no cure for this disorder to date.

A team of researchers from ETH Zurich and the University Children’s Hospital Zurich have now applied a newly developed editing tool to correct the mutated genes in the liver cells of mice.

The tool works by changing the sequence of the DNA building blocks for the corresponding gene. To transfer the genetic code for the new editing tool to the liver cells, the researchers implanted the required genes into adeno-associated viruses and injected them into the blood of the mice. The virus then infected the liver cells and introduced the genes for the editing tool into the liver cells.

Thanks to their approach, the researchers have succeeded in healing the disease in mice.

“This approach has great potential for application in humans,” said ETH Professor Gerald Schwank. He warned, however, that several more tests will have to be carried out in other animals before the new genome editing tool can be used in humans.