Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 21, one copy inherited from each parent, form one of the pairs. Chromosome 21 is the smallest human chromosome, spanning about 47 million base pairs (the building blocks of DNA) and representing approximately 1.5 percent of the total DNA in cells.
In 2000, researchers working on the Human Genome Project announced that they had determined the sequence of base pairs that make up this chromosome. Chromosome 21 was the second human chromosome to be fully sequenced.
Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 21 likely contains between 300 and 400 genes.
Genes on chromosome 21 are among the estimated 20,000 to 25,000 total genes in the human genome.
A team of investigators from Massachusetts General Hospital (MGH), Brigham and Women's Hospital (BWH), and the Broad Institute of MIT and Harvard have developed a non-invasive genetic test that can screen the blood of pregnant individuals to survey all genes for fetal DNA sequence variants.
A team of researchers at the Texas A&M University School of Veterinary Medicine & Biomedical Sciences (VMBS) has received a grant from the National Institutes of Health (NIH) to research metabolism in people with Down syndrome.
Scientists discuss the intricate relationship between the nervous and stomatognathic systems.
Neurologist Beau Ances, MD, PhD, talks with his patient, Adam Kloppenberg, who has Down syndrome, at Washington University School of Medicine in St. Louis. People with Down syndrome are at very high risk of developing Alzheimer's disease. Ances is involved in a project led by Jason Hassenstab, PhD, an associate professor of neurology, to develop tools to measure cognitive function in people with Down syndrome-associated Alzheimer's disease.
Individuals with Down syndrome, the genetic condition caused by triplication of human chromosome 21, also known as trisomy 21, display a very high risk of hospitalization and mortality after developing lung infections.
People with Down syndrome, the condition caused by an extra copy of chromosome 21, or trisomy 21, display chronic dysregulation of their immune system, which can contribute to high rates of autoimmune conditions and severe complications from respiratory infections.
An overdosed gene on chromosome 21 causes people with Down's Syndrome to age faster than the general population.
Researchers at the Francis Crick Institute, King's College London and University College London have shed light on the genetics behind changes in the structure and shape of the face and head in a mouse model of Down Syndrome.
An extra copy of a gene that controls synapse formation in the cortex causes excessive inhibitory signaling and may contribute to Down syndrome, according to a new study publishing April 20th in the open access journal PLOS Biology by Bing Ye of the University of Michigan, US, and colleagues.
National Institutes of Health researchers compared a new genetic animal model of Down syndrome to the standard model and found the updated version to be more similar to the changes seen in humans.
People with a third copy of chromosome 21, known as trisomy 21, are at high risk of developing Acute Myeloid Leukaemia (AML), an aggressive form of blood cancer.
Scientists at the Icahn School of Medicine at Mount Sinai in New York have identified which parts of the immune system go awry and contribute to autoimmune diseases in individuals with Down syndrome.
Amyloid plaques — protein clumps that are one of the hallmarks of Alzheimer's disease—occur at roughly the same level in the brains of people with Down syndrome who have Alzheimer's as they do in people with forms of hereditary, early-onset Alzheimer's, according to research funded by the National Institutes of Health.
Individuals with Down syndrome have less-frequent viral infections, but when present, these infections lead to more severe disease.
Gonadotropin-releasing hormone (GnRH) therapy improves cognitive function in Down syndrome (DS) mouse models and male patients with DS, according to a new study.
Children with Down syndrome prefer food with a crispy, oily mouthfeel and don't like brittle or gooey foods. But those preferences can lead to a less nutritious diet, according to Washington State University research published in the Journal of Texture Studies.
Around 80% of people with Down syndrome develop Alzheimer's disease, often when they are between 40 and 50 years old.
New research by a scientist at the Milner Center for Evolution at the University of Bath suggests that "selfish chromosomes" explain why most human embryos die very early on. The study, published in PLoS, Biology, explaining why fish embryos are fine but sadly humans' embryos often don't survive, has implications for the treatment of infertility.
Lamivudine, a commonly-used antiretroviral drug for treating HIV, improves cognition in a mouse model of Down syndrome, according to the findings of a joint new study by researchers at the Centre for Genomic Regulation (CRG) and the IrsiCaixa AIDS Research Institute, a center jointly promoted by the "la Caixa" Foundation and the Department of Health of the Generalitat de Catalunya.
New research shows how genetic variations linked to severe cases of COVID-19 affect our immune cells.