Chromosome 21 News and Research

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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.
Research can bring new possibilities for earlier diagnosis, preventive treatment of dementia

Research can bring new possibilities for earlier diagnosis, preventive treatment of dementia

$109 million NIH grant awarded to expand Alzheimer's disease and Down syndrome research

$109 million NIH grant awarded to expand Alzheimer's disease and Down syndrome research

Life-threatening COVID-19 associated with specific genetic variants

Life-threatening COVID-19 associated with specific genetic variants

New therapeutic possibilities for treating intellectual disability in Down syndrome

New therapeutic possibilities for treating intellectual disability in Down syndrome

Modifiable risk factors could play important role in Alzheimer's disease, study finds

Modifiable risk factors could play important role in Alzheimer's disease, study finds

MU researchers describe Down syndrome-associated catatonia

MU researchers describe Down syndrome-associated catatonia

Scientists reverse learning and memory deficits with drugs in animal model of Down syndrome

Scientists reverse learning and memory deficits with drugs in animal model of Down syndrome

Study uncovers cause for spatial-memory deficits in people with Down syndrome

Study uncovers cause for spatial-memory deficits in people with Down syndrome

Wisconsin study: 3 in 5 people with Down syndrome diagnosed with dementia by age 55

Wisconsin study: 3 in 5 people with Down syndrome diagnosed with dementia by age 55

Researchers receive $3.2 million NIH grant to pursue a deeper understanding of Down syndrome

Researchers receive $3.2 million NIH grant to pursue a deeper understanding of Down syndrome

BU professor awarded NIH grant to study Down syndrome

BU professor awarded NIH grant to study Down syndrome

Rutgers-led study pinpoints key gene linked to impaired memory in Down syndrome

Rutgers-led study pinpoints key gene linked to impaired memory in Down syndrome

MIT announces creation of the Alana Down Syndrome Center

MIT announces creation of the Alana Down Syndrome Center

Cannabinoid receptor type 1 appears to be potential target to treat Down syndrome

Cannabinoid receptor type 1 appears to be potential target to treat Down syndrome

European scientists aim to identify causes of dementia

European scientists aim to identify causes of dementia

MUHC's 'Dr. House' discovers new genetic disease and the gene responsible for it

MUHC's 'Dr. House' discovers new genetic disease and the gene responsible for it

Down syndrome may hold important clues to onset of Alzheimer's disease

Down syndrome may hold important clues to onset of Alzheimer's disease

Children born with Down's syndrome have superior genome that compensates for disability

Children born with Down's syndrome have superior genome that compensates for disability

New technique may reveal clues about role of centromeres in Down syndrome, other birth defects

New technique may reveal clues about role of centromeres in Down syndrome, other birth defects

Research aims to raise awareness of higher rate of testicular cancer in patients with DS

Research aims to raise awareness of higher rate of testicular cancer in patients with DS