Novel insight into chromosome 21 and its effect on Down syndrome

A UCL-led research team has, for the first time, identified specific regions of chromosome 21, which cause memory and decision-making problems in mice with Down syndrome, a finding that provides valuable new insight into the condition in humans. Most people have 46 chromosomes in each cell, divided into 23 pairs: people with Down syndrome (DS) have an extra copy of chromosome 21, which carries over 200 genes. In this study, published in  Cell Reports , researchers at UCL, supported by Cardiff University and the Francis Crick Institute, used mouse models to try and find out how having these extra genes causes learning disability. Chromosome 21 and its genes are also found in mice, although the genes have dispersed onto three smaller regions on three different mouse chromosomes. These are mouse chromosomes 16, 10 and 17 containing 148 genes, 62 genes and 19 genes respectively. The researchers looked at the effect of the genes in each of these three different mouse regions (chromosomes) on learning and memory. To do this three different mouse strains (groups of mice), were genetically modified to carry an extra copy of one of the gene groups on mouse chromosomes 16, 10 or 17.