2024年11月12日 · Any one of three genetic changes can cause Down syndrome: Trisomy 21. About 95% of the time, Down syndrome is caused by trisomy 21. This means the person has three copies of chromosome 21, instead of the usual two copies. The extra chromosome 21 is in all cells in the body.

Down syndrome or Down's syndrome, [12] also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. [3] It is usually associated with developmental delays, mild to moderate intellectual disability , …

Trisomy 21 is the most common chromosomal anomaly in humans, affecting about 5,000 babies born each year and more than 350,000 people in the United States. Also known as Down syndrome, trisomy 21 is a genetic condition caused by an extra chromosome.

2023年1月31日 · Trisomy 21 is the most common type of Down syndrome. The term “ trisomy ” means having an extra copy of a chromosome. Trisomy 21 occurs when a developing fetus has three copies of chromosome 21 in every cell instead of the typical two copies.

2024年12月26日 · About 95% of people with Down syndrome have Trisomy 21. In this type, an extra part or a whole extra chromosome 21 is present. However, the extra chromosome is attached or "trans-located" to a different chromosome rather than being a separate chromosome 21. This type accounts for about 3% of people with Down syndrome.

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.

2 天之前 · Down syndrome (also called Trisomy 21) is a genetic condition caused by an error in the process that replicates and then divides up the pairs of chromosomes during cell division, resulting in the inheritance of an extra full or partial copy of chromosome 21 from a parent.

Down syndrome is an abnormality of chromosome 21 that can cause intellectual disability, microcephaly, short stature, and characteristic facies. Diagnosis is suggested by physical anomalies and abnormal development and confirmed by cytogenetic analysis. Management depends on specific manifestations and anomalies.

Down syndrome is caused by an extra chromosome 21. Children with Down syndrome have delayed physical and mental development, specific head and facial features, and are often short. Before birth, Down syndrome may be suspected based on ultrasonography or tests on the mother's blood and confirmed using chorionic villus sampling and/or amniocentesis .

Down syndrome is a genetic disorder in which a person has an extra copy of a chromosome called chromosome 21. This extra chromosome causes many health problems. What causes Down syndrome? Down syndrome is caused by abnormalities in one of the chromosomes. People with Down syndrome have an extra 21st chromosome.