About Down Syndrome - National Human Genome Research …
2017年6月29日 · Down syndrome is a chromosomal condition related to chromosome 21. It affects 1 in 800 to 1 in 1000 live born infants. What are the symptoms of Down syndrome? People who have Down syndrome have learning difficulties, mental disability, a characteristic facial appearance, and poor muscle tone (hypotonia) in infancy.
Down syndrome - Symptoms and causes - Mayo Clinic
2024年11月12日 · Down syndrome is a genetic condition caused when an unusual cell division results in an extra full or partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical features of Down syndrome.
Down Syndrome - StatPearls - NCBI Bookshelf
2023年8月8日 · Down syndrome (trisomy 21) is a genetic disorder caused by the presence of all or a portion of a third chromosome 21. Patients typically present with mild to moderate intellectual disability, growth retardation, and characteristic facial features.
Genetics of Down syndrome - Wikipedia
Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole (trisomy 21) or part (such as due to translocations).
Down syndrome: MedlinePlus Genetics
Down syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. Explore symptoms, inheritance, genetics of this condition.
Down Syndrome | Birth Defects | CDC - Centers for Disease ...
2024年12月26日 · Down syndrome is a genetic condition where a person is born with an extra chromosome. This can affect how their brain and body develop. People diagnosed with Down syndrome can lead healthy lives with supportive care.
Down Syndrome: Symptoms & Causes - Cleveland Clinic
2023年1月31日 · Down syndrome is a genetic condition where a person is born with an extra copy of chromosome 21. This means that they have a total of 47 chromosomes instead of 46. This can affect how their brain and body develop. People diagnosed with Down syndrome have happy and healthy lives with supportive care.