Steroids are also given to reduce brain swelling by stopping extra fluid entering brain cells and increasing their volume.

BBC: Heading for trouble

Because only some cells contain the extra X chromosome, females with the mosaic form of triple X syndrome may have less severe symptoms.

CNN: Triple X syndrome

There are also an extra 400 people being held in police cells due to prison overcrowding.

BBC: NEWS | UK | Over 108,000 in detention in UK

To save themselves when they are threatened with being overwhelmed by lipids, cells become insulin-resistant, which stops them taking up extra glucose which would then be converted into lipids.

ECONOMIST: Metabolic syndrome

Mr Elliott said it was clear that the extra 163 genes produced extra chemical messengers which could disrupt the function of any of the 22, 450 genes contained in the cells of people with Down's.

BBC: NEWS | Health | Down's syndrome theory shattered