In the context of disability, DS most commonly refers to Down syndrome.
Down Syndrome (DS) Explained
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. This extra genetic material alters developmental changes and causes the characteristics associated with Down syndrome. It's also referred to as Trisomy 21.
Causes of Down Syndrome
Down syndrome usually occurs due to a random error in cell division during the development of the egg or sperm. There are three genetic variations that can cause Down syndrome:
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Trisomy 21 (Nondisjunction): This accounts for about 95% of cases. It happens when a person has three copies of chromosome 21, instead of the usual two, in all cells. This is typically caused by a failure of the 21st chromosome to separate during egg or sperm development (nondisjunction).
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Translocation: In this case, a part of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception. Individuals have the usual two copies of chromosome 21, but they also have additional material from chromosome 21 attached to the other chromosome.
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Mosaicism: This is a rarer form, where some cells have the extra chromosome 21, and others do not. Mosaicism results from abnormal cell division after fertilization.
Characteristics Associated with Down Syndrome
People with Down syndrome typically have some, but not all, of the following characteristics:
- Distinct facial features (flattened face, small head, short neck, protruding tongue, upward slanting eyes)
- Intellectual disability
- Developmental delays
- Heart defects
- Hearing loss
- Vision problems
- Hypotonia (poor muscle tone)
Down Syndrome as a Disability
Down syndrome is considered a disability because it impacts a person's cognitive abilities, physical development, and overall well-being, often requiring ongoing support and services. Individuals with Down syndrome can live fulfilling lives with proper care, education, and therapies.
