Health

New light shed on the causes of Down’s syndrome



A new insight into the causes of Down’s syndrome was revealed today by London scientists.

They found the genetic factors that cause the learning disability were more varied than previously thought.

The University College London-led team of researchers described the findings as a “complete surprise” and said they could pave the way for different therapies. About one in 800 babies worldwide are born with Down’s syndrome, with the prevalence rising due to older mothers. 

The condition is caused by a chance happening at the time of conception that results in an extra copy of chromosome 21. Pregnant women are offered NHS screening to check for the syndrome.


The UCL team, supported by Cardiff university and the Francis Crick Institute, carried out memory and decision-making tests on genetic-ally modified mice.

In mice, chromosome 21 and its 200 genes disperses into three other chromosomes, or regions, within the brain. 

The test mice were given an extra chromosome in one of the three regions. Then they were monitored as they navigated a “left-right” maze.

Researchers found that one of the groups had worse memory and irregular signals in the hippocampus, a part of the brain known to be very important for memory. 

Another group had poor signalling between the hippocampus and pre-frontal cortex, which is needed for planning and decision-making. 

The third group had no unusual electrical activity in the brain. The findings were published today in Cell Reports.

Co-author Professor Matthew Walker, of UCL Queen Square Institute of Neurology, said: “Scientists have traditionally worked on the hypothesis that a single gene, or single genes, was the likely cause of intellectual disabilities associated with Down’s syndrome. We have shown — for the first time — that different and multiple genes are contributing to the various cognitive problems associated with Down’s syndrome.”

Therapies for people with Down’s syndrome can include speech and language therapy, physiotherapy and occupational therapy.

Professor Elizabeth Fisher, also of the Institute of Neurology, said the study’s insights imply that therapies for people with Down syndrome “should perhaps target multiple processes, and we have made the initial steps in identifying what some of these processes are”.



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