What is Duchenne muscular dystrophy?

UP NHM CHO 7 Sept 2022(shift-1st)

Pathology & Genetics

Easy

Appeared in: UP NHM CHO 7 Sept 2022(shift-1st)

Explanation

Duchenne muscular dystrophy (DMD) is inherited as an X-linked recessive trait.
The mutation occurs in the dystrophin gene, which is located on the X chromosome (Xp21 locus).
Because males have only one X chromosome, a single copy of the mutated gene is sufficient to cause the disease.
Females are typically carriers as they have a second, normal X chromosome that can compensate, though they can pass the mutated gene to their offspring.

Option A: An acquired disorder is one that develops after birth due to external factors (e.g., infection, injury). DMD is a genetic condition, meaning it is inherited and present from birth.
Option B: Autosomal recessive inheritance means the gene is on a non-sex chromosome (autosome) and two copies of the mutated gene are needed to cause the disease. The DMD gene is on the X chromosome (a sex chromosome).
Option C: Autosomal dominant inheritance means the gene is on an autosome and only one copy of the mutated gene is needed to cause the disease. The DMD gene is on the X chromosome, and its inheritance pattern is recessive.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Genetic inheritance pattern of Duchenne Muscular Dystrophy (DMD) as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in the multidisciplinary care of patients with DMD, focusing on managing symptoms, promoting mobility, providing respiratory support, and offering psychosocial support to the patient and family.
Genetic counseling is essential for families with a history of DMD. Nurses can help identify at-risk family members and provide education and support regarding carrier testing and reproductive options.
What if a female presents with significant muscle weakness and is diagnosed with DMD? This is rare but can occur due to 'skewed X-inactivation,' where the healthy X chromosome is preferentially inactivated in most muscle cells, leading to symptoms. The nursing approach would be similar, focusing on managing her specific symptoms and functional limitations.

How to Approach the Question

First, identify the core subject of the question: Duchenne muscular dystrophy (DMD).
This is a factual recall question that tests your knowledge of genetic disorders.
Recall the specific genetic classification of DMD. Key associations are 'muscular dystrophy,' 'boys,' and 'Gower's sign,' which point towards a classic X-linked disease.
Evaluate the options based on the principles of genetic inheritance.
Eliminate 'Acquired disorder' because DMD is known to be genetic.
Differentiate between 'Autosomal' (non-sex chromosomes) and 'X-linked' (sex chromosome). Since DMD primarily affects males, an X-linked pattern is highly likely.

Concept Tested & Keywords

Concept Tested: Genetic inheritance pattern of Duchenne Muscular Dystrophy (DMD)
Stem keywords: Duchenne muscular dystrophy, genetic disorder
Lead-in keywords: What is
Negative lead-in flag: false

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 1230-1232

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 pp. 1634-1636, 1635-1637