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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 ...
Bloom syndrome (often abbreviated as BS in literature) [1] is a rare autosomal recessive genetic disorder characterized by short stature, predisposition to the development of cancer, and genomic instability. BS is caused by mutations in the BLM gene which is a member of the RecQ DNA helicase family. Mutations in genes encoding other members of ...
XX male syndrome, also known as de la Chapelle syndrome, is a rare condition in which an individual with a 46,XX karyotype develops a male phenotype. Synonyms for XX male syndrome include 46,XX testicular difference of sex development (or 46,XX DSD)
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]
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, 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.
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.
