Down syndrome is also known as?

Appeared in: RRB Nsg. Superintendent 21 July 2019 (shift 1st)

Explanation

Down syndrome is a genetic disorder resulting from an extra copy of chromosome 21.
The term 'Trisomy 21' directly refers to this genetic makeup, where there are three copies of chromosome 21 instead of the usual two.
It is the most common nonlethal trisomy, occurring in approximately 1 in 700 live births.
Characteristic features include intellectual disability, a flattened facial profile, upward-slanting eyes, and a single deep crease across the palm of the hand (simian crease).

Option A: Trisomy 13 is the genetic basis for Patau syndrome, not Down syndrome.
Option B: Trisomy 18 is the genetic cause of Edwards syndrome, a different and more severe condition than Down syndrome.
Option D: Monosomy 13 refers to the absence of one copy of chromosome 13. 'Mono' means one, whereas 'Tri' in Trisomy means three.

Visual 1: Karyotype - A diagram showing the 23 pairs of human chromosomes, with an arrow pointing to the three copies of chromosome 21, illustrating Trisomy 21.
Visual 2: Infographic - A comparative chart showing the key physical features of infants with Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13).

Clinical Relevance

Nursing practice connection: Knowing Chromosomal Abnormalities helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a crucial role in supporting families of newborns diagnosed with Down syndrome, providing education on associated health issues like congenital heart defects (in ~50% of cases), feeding difficulties due to hypotonia, and the importance of early intervention programs.
Prenatal screening tests, such as non-invasive prenatal testing (NIPT), can detect an increased risk for Trisomy 21, allowing for early counseling and preparation.
What if? If a prenatal screening test comes back positive for Trisomy 13 (Patau syndrome) instead of Trisomy 21, the nursing focus shifts dramatically to palliative care counseling and preparing the family for an infant with a life-limiting condition, as survival beyond the first year is rare.

How to Approach the Question

Identify the core concept in the question: 'Down syndrome'.
Recall the genetic basis of Down syndrome. The name itself provides a clue, but the key is knowing it's a chromosomal abnormality.
Analyze the options. 'Trisomy' means three copies of a chromosome, and 'Monosomy' means one copy.
Associate 'Down syndrome' with the specific chromosome involved, which is chromosome 21.
Therefore, 'Trisomy 21' is the correct medical term.
Eliminate the other options by recalling that Trisomy 13 is Patau syndrome and Trisomy 18 is Edwards syndrome, both of which have distinct and more severe phenotypes.

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent 21 July 2019 (shift 1st)

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