Researchers in Switzerland have taken a closer look at the cells of Down’s syndrome patients, with widespread changes in protein expression observed.
Down’s syndrome, or trisomy 21, is the most common genetic disease, characterized by facial dysmorphism, learning disabilities, poor muscle tone and heart problems. Research carried out at the University of Geneva and ETH Zurich and published in Nature Communications shows that the condition doesn’t just affect the genes on chromosome 21, but also those located further afield. The researchers looked at the proteome of cells – all of the proteins that they express – during the study, a technique that could help to unearth more information about other diseases.
Typically, every cell in the body contains 23 pairs of chromosomes, half from the father and half from the mother. However, in Down’s syndrome, an individual receives an extra full or partial copy of chromosome 21 due to an error during the splitting of chromosomes between sperm and egg cells. In the US alone, the condition affects approximately 1 in every 700, around 6,000 babies, born each year.
It was previously believed that Down’s syndrome only affected the proteins encoded by the chromosome 21 genes, but the study shows that genes on the other chromosomes are also affected. This leads to a massive overexpression of huge numbers of genes, which overwhelms the cells that cannot bring the protein surplus under control.
The geneticists also observed that the cell’s sub-structures were affected. In the case of mitochondria, its proteins were hugely reduced, preventing it from functioning correctly. Finally, the study indicated that different types of proteins were affected in alternative ways. Proteins that form complexes were degraded quickly, while there was an excess of solitary proteins.
This is a big step forward in our understanding of Down’s syndrome. The techniques used during the study open new doors for the investigation of other genetic diseases. Stylianos Antonarakis, Professor at the University of Geneva, set out what the group will look into next: “We now need to find which of the deregulated proteins are responsible for each particular symptom of Down’s syndrome.” A new technique, Trim-Away, has been developed by researchers in Germany and the UK to remove a protein so that its true function can be discovered, which could be useful.
Although these findings do not directly give us ways to treat the condition, we do seem to be moving in the right direction. Once targets have been identified, biotechs across Europe can begin using their powerful technology to develop therapeutics. One field that could help to remove unwanted proteins is RNAi, with Sanofi and Alnylam Therapeutics kicking off discussions with the FDA and EMA to approve the first commercial RNAi therapy, patisiran.
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