Which condition is also known as Trisomy-18?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

Edward syndrome is the correct medical term for Trisomy 18.
This is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18.
It is the second-most common autosomal trisomy after Down syndrome.
Key features include intrauterine growth restriction, heart defects, a small head (microcephaly), clenched hands with overlapping fingers, and rocker-bottom feet.
The prognosis is poor, with most infants not surviving past the first year of life.

Option A: Turner syndrome is a monosomy, not a trisomy. It is caused by the absence of one of the two X chromosomes in females (45,X).
Option B: Patau syndrome is Trisomy 13, which is caused by an extra copy of chromosome 13.
Option D: Down syndrome is Trisomy 21, the most common chromosomal disorder, caused by an extra copy of chromosome 21.

Visual 1: Karyotype - A comparative karyotype showing a normal set of chromosomes versus the karyotype for Trisomy 18 (Edward syndrome), highlighting the extra chromosome 18.
Visual 2: Infographic - A chart summarizing the key features, chromosomal defect, and names of common trisomies (Down, Edward, Patau) and other chromosomal disorders (Turner, Klinefelter).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Genetic Disorders: Trisomies as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in supporting families of infants with Trisomy 18, providing education on the condition, managing complex symptoms, and coordinating palliative or hospice care due to the poor prognosis.
Genetic counseling is essential for parents who have had a child with a trisomy to discuss the risk of recurrence in future pregnancies and available prenatal screening options.
What if? If the question asked for the most common trisomy compatible with postnatal survival, the answer would be Down syndrome (Trisomy 21), not Edward syndrome (Trisomy 18), which has a much lower survival rate.

How to Approach the Question

This is a factual recall question testing knowledge of specific genetic syndromes and their corresponding chromosomal abnormalities.
Identify the key term in the question: 'Trisomy-18'.
Recall the common names for the major trisomies.
Evaluate each option against your knowledge:
Turner syndrome is Monosomy X.
Patau syndrome is Trisomy 13.

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Attempt every question from this paper in a timed mock, then review the full solution for each one.