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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, and characteristic physical features.
When there is an extra chromosome 21, the result is Down syndrome. There are three genetic variations of Down syndrome: Trisomy 21: This occurs when there is a third copy of chromosome 21. This is ...
The extra chromosome 21 material that causes Down syndrome may be due to a Robertsonian translocation. The long arm of chromosome 21 is attached to the long arm of another chromosome, often chromosome 14 [46,XX,t(14;21)] or itself [called an isochromosome , 45,XX,t(21;21)(q10;q10)] as seen in the translocation karyotype figure.
Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. [1] It is typically associated with developmental delays, characteristic physical features, and mild to moderate intellectual disability. [2] The average IQ of a young adult with Down syndrome is 50, equivalent to the mental age of an 8 ...
[citation needed] An example of trisomy in humans is Down syndrome, which is a developmental disorder caused by an extra copy of chromosome 21; the disorder is therefore also called "trisomy 21". [7] An example of monosomy in humans is Turner syndrome, where the individual is born with only one sex chromosome, an X. [8]
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child. There are over 6,000 known genetic disorders in humans.
Karyotype of a human with Trisomy 21 (Down syndrome). Trisomies can occur with any chromosome, but often result in miscarriage rather than live birth.For example, Trisomy 16 is most common in human pregnancies, occurring in more than 1%, but the only surviving embryos are those having some normal cells in addition to the trisomic cells (mosaic trisomy 16). [3]
Down syndrome is the most common genetic condition in the U.S. Approximately 400,000 Americans have Down syndrome. Here are amazing individuals with Down syndrome who are breaking the barriers of ...