At the time the article was last revised Travis Fahrenhorst-Jones had no financial relationships to ineligible companies to disclose. Down syndrome or trisomy 21 is the most common trisomy and also the commonest chromosomal disorder.
It is a major cause of intellectual disability and has numerous additional multisystem manifestations. The approximate worldwide incidence is approximately 1 in live births The individual risk is strongly dependent on maternal risk, and therefore incidence varies with regional and temporal variation in maternal age distribution and the implementation of antenatal screening.
Diagnosis is often made antenatally and this must occur in conjunction with genetic counseling, which should begin prior to the testing. In the postnatal period, characteristic phenotypical features point to the diagnosis:. Intellectual disability becomes evident in early childhood as the failure to reach developmental milestones in an expected timeframe.
An alternative chromosomal abnormality that results in the syndrome involves Robertsonian translocation of paternal chromosomal material, such that the overall number of chromosomes remains the same. Cognitive disability and epilepsy are the most common neurological manifestations 8.
Structurally evident abnormalities include:. Alzheimer disease developing in virtually all patients older than 40 years. In particular, defects affecting the endocardial cushion are common:. The manifestations of Down syndrome are protean and can affect multiple systems.
Some of these are better discussed under individual features in the wide clinicopathological spectrum of the condition listed above. These are discussed in detail in a separate article. Life expectancy for individuals with Down Syndrome has increased signigicantly due to a reduction in rates of institutionalization and improved medical care in the past several decades In the United States in individuals with Down syndrome lived on average about 10 years while in individuals with Down syndrome lived to approximately 47 years of age Respiratory infections stay considerably predominant cause of death.
Moreover, other causes of early mortality, include congenital heart defects and dementia Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form. Check for errors and try again.
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