Which condition is associated with Down's syndrome?

PGIMS Rohtak NO - 2017

Pathology & Genetics

Easy

Appeared in: PGIMS Rohtak NO - 2017

Explanation

Trisomy 21 is the correct answer as it is the specific chromosomal abnormality that causes Down's syndrome.
This condition occurs when an individual has a full or partial extra copy of chromosome 21.
It is the most common chromosomal disorder and the leading cause of intellectual disability.
The provided image of a karyotype visually confirms the presence of three copies of chromosome 21.

Option B: Trisomy 18 is the genetic cause for Edwards syndrome, a separate and distinct chromosomal disorder with different clinical features.
Option C: Dislocations are a potential musculoskeletal complication seen in individuals with Down's syndrome due to hypotonia and ligamentous laxity. It is a clinical feature, not the underlying genetic cause.
Option D: Mosaicism is a less common type of Down's syndrome, accounting for only 1-2% of cases. While it is a form of the syndrome, Trisomy 21 is the overarching term for the chromosomal error and the cause in the vast majority (~95%) of cases, making it the best and most comprehensive answer.

Clinical Relevance

Nursing practice connection: Knowing The concept tested is the understanding of the primary genetic cause of Down's syndrome helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a crucial role in the early identification and management of health issues associated with Down's syndrome. This includes conducting thorough newborn assessments to screen for common features like hypotonia, a single palmar crease, and specific facial characteristics.
Early screening for comorbidities is vital. About 40% of infants with Down's syndrome have congenital heart defects, so cardiac screening is a priority. Other common issues include hearing and vision problems, and thyroid dysfunction.
Providing support and resources to the family is a key nursing responsibility. This includes explaining the diagnosis, connecting them with support groups, and coordinating with early intervention services to optimize the child's development.

How to Approach the Question

First, analyze the question to identify the core concept being tested, which is the cause of Down's syndrome.
Examine the provided image. Recognize it as a karyotype and look for abnormalities. Note the three copies of chromosome 21.
Evaluate each option based on your knowledge and the visual evidence. 'Trisomy 21' directly describes the finding in the karyotype.
Differentiate between the primary cause and related concepts. Trisomy 18 is a different syndrome. Dislocations are a complication. Mosaicism is a subtype.
Select the option that represents the most common and fundamental cause. Trisomy 21 accounts for ~95% of cases and is the defining feature, making it the best answer.

Concept Tested & Keywords

Concept Tested: The concept tested is the understanding of the primary genetic cause of Down's syndrome.
Stem keywords: Down's syndrome, condition, associated
Lead-in keywords: Which

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