We show that a duplicated segment on one of their chromosomes-21 encompassing only 13% of chromosomal gene content is sufficient to cause accelerated IgG-glycan ageing changes seen in DS cohorts, accompanied by an increased presence of DNA double-strand break (DSB)-repair foci and decreased Lamin B1 levels in blood cell nuclei. This evidence concerns the gene LMNB1 and Dravet syndrome.