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Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with developmental delays, mild to moderate intellectual disability, and characteristic physical features.
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 ). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy, genetic background ...
Specialty. Genetics. 22q13 deletion syndrome, known as Phelan–McDermid syndrome ( PMS ), is a genetic disorder caused by deletions or rearrangements on the q terminal end (long arm) of chromosome 22. Any abnormal genetic variation in the q13 region that presents with significant manifestations ( phenotype) typical of a terminal deletion may ...
Brunner syndrome is a rare genetic disorder associated with a mutation in the MAOA gene. It is characterized by lower than average IQ (typically about 85), problematic impulsive behavior (such as pyromania, hypersexuality and violence), sleep disorders and mood swings.
DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is a syndrome caused by a microdeletion on the long arm of chromosome 22. [7] While the symptoms can vary, they often include congenital heart problems, specific facial features, frequent infections, developmental disability, intellectual disability and cleft palate. [7]
Down syndrome, a common chromosomal disease, is caused by trisomy of chromosome 21. Patau syndrome is caused by trisomy of chromosome 13. Trisomy 9 , believed to be the 4th most common trisomy, has many long lived affected individuals but only in a form other than a full trisomy, such as trisomy 9p syndrome or mosaic trisomy 9.
Research of Down syndrome-related genes is based on studying the genes located on chromosome 21. In general, this leads to an overexpression of the genes. Understanding the genes involved may help to target medical treatment to individuals with Down syndrome. It is estimated that chromosome 21 contains 200 to 250 genes.
Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with developmental delays, characteristic physical features, and mild to moderate intellectual disability . [2]
World Down Syndrome Day ( WDSD) is marked each year on March 21, [1] beginning in 2007. The 21st day of March (the 3rd month of the year) was selected to signify the uniqueness of the triplication ( trisomy) of the 21st chromosome which causes Down syndrome.
John Langdon Haydon Down (18 November 1828 – 7 October 1896) was a British physician best known for his description of the genetic condition now known as Down syndrome, which he originally classified in 1862.