Down syndrome

(noun)

A genetic disorder caused by the presence of all or part of a third copy of chromosome 21, associated with physical growth delays, certain characteristic facial features, and mild to moderate intellectual disability.

Related Terms

Examples of Down syndrome in the following topics:

  • Down Syndrome

    • Down syndrome or Down's syndrome, also known as trisomy 21, is a chromosomal condition caused by the presence of all or part of a third copy of chromosome 21.
    • This is the cause of 1–2% of the observed Down syndromes.
    • Translocation Down syndrome is often referred to as familial Down syndrome.
    • It is the cause of 2–3% of observed cases of Down syndrome.
    • Many standard prenatal screens can discover Down syndrome.

  • Intellectual Disabilities

    • The average full-scale IQ of young adults with Down syndrome is around 50.
    • Education and proper care have been shown to improve quality of life for individuals with Down Syndrome.
    • Some children with Down syndrome are educated in typical school classes, while others require more specialized education.
    • Some individuals with Down syndrome graduate from high school and a few go on to post-secondary education.
    • Down Syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21.

  • Genetic Basis of Intelligence and Learning

    • Approaches in cognitive genomics have been used to investigate the genetic causes for many learning disabilities, such as dyslexia, and neural disorders such as Down syndrome, autism, and Alzheimer's disease.
    • Down syndrome, for example, is a genetic syndrome marked by intellectual disability, and has implications for the ways in which children with Down syndrome learn.
    • While experts believe the genetic cause for the syndrome is a lack of genes in the 21st chromosome, the gene(s) responsible for the cognitive symptoms have yet to be discovered.

  • The Middle Years

    • Advanced maternal age increases the risk of a child being born with some disorders, such as Down syndrome.
    • Advanced paternal age sharply increases the risk of miscarriage, as well as Down syndrome, schizophrenia, autism, and bipolar disorder.

  • Intellectual Disabilities

    • Intellectual disability can be either syndromic (in which intellectual deficits are present along with other medical and behavioral signs and symptoms), or non-syndromic (in which intellectual deficits appear without other abnormalities).
    • Down syndrome and fragile X syndrome are examples of syndromic intellectual disabilities.
    • The most prevalent genetic conditions include Down syndrome, Klinefelter's syndrome, fragile X syndrome (common among boys), neurofibromatosis, congenital hypothyroidism, Williams syndrome, phenylketonuria (PKU), and Prader-Willi syndrome.
    • Down syndrome is one of the more common genetic causes of intellectual disability.

  • Disorders in Chromosome Number

    • Aneuploidy often results in serious problems such as Turner syndrome, a monosomy in which females may contain all or part of an X chromosome.
    • Klinefelter syndrome is a trisomy genetic disorder in males caused by the presence of one or more X chromosomes.
    • Down syndrome is the only autosomal trisomy in humans that has a substantial number of survivors one year after birth.
    • Trisomy in chromosome 21 is the cause of Down syndrome; it affects 1 infant in every 800 live births.

  • Chromosomes and Genes

    • Common abnormalities include Down syndrome (caused by an extra chromosome #21), Klinefelter syndrome (caused by an extra X chromosome), and Turner syndrome (caused by a missing X chromosome).
    • Many chromosomal abnormalities are of psychological importance, with substantial impacts on mental processes; for example, Down syndrome can cause mild to moderate intellectual disabilities.

  • Horner's Syndrome

    • Horner's syndrome may also occur during a migraine attack and resolve after the migraine.
    • Treatment of Horner's syndrome requires that the underlying cause of the syndrome be identified.
    • Horner's syndrome is more of a symptom than an actual, independent disease.
    • The numbers indicate sites of possible lesions on the nerves that cause Horner's syndrome.
    • This patient exhibits Horner's syndrome on the left side of face.

  • Marfan Syndrome

    • Marfan syndrome is a genetic disorder of the connective tissue.
    • Marfan syndrome has a range of expressions, from mild to severe.
    • Marfan syndrome can also seriously affect the eyes and vision.
    • An aortic dissection is most often fatal and presents with pain radiating down the back, giving a tearing sensation.
    • Marfan syndrome is a risk factor for spontaneous pneumothorax.

  • Chronic Fatigue Syndrome

    • Chronic fatigue syndrome (CFS) is the most common persistent fatigue syndrome that affects people.
    • Chronic fatigue syndrome (CFS) is the most common name used to designate a significantly debilitating medical disorder or group of disorders.
    • The disorder may also be referred to as myalgic encephalomyelitis (ME), post-viral fatigue syndrome (PVFS), chronic fatigue immune dysfunction syndrome (CFIDS), or several other terms.
    • An Australian prospective study found that after infection by viral and non-viral pathogens, a sub-set of individuals met the criteria for CFS, with the researchers concluding that "post-infective fatigue syndrome is a valid illness model for investigating one pathophysiological pathway to CFS".