Question:medium
Which of the following is NOT a congenital myopathy?
Which of the following is NOT a congenital myopathy?
Show Hint
Central core, nemaline, and centronuclear myopathy are the classic congenital myopathy triad; Z band (myofibrillar) myopathy is a separate, usually adult-onset group.
Updated On: Jul 8, 2026
- Central Core Disease
- Nemaline Myopathy
- Centronuclear Myopathy
- Z Band Myopathy
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Set the definition to test against.
A congenital myopathy is a structural muscle disease present from birth, diagnosed by a specific pattern on muscle biopsy, not by fiber necrosis as in a true dystrophy. Three names have carried this label for decades.
Step 2: Walk through the classic three.
Central core disease shows pale, enzyme-poor cores running down the centre of fibers. Nemaline myopathy shows small rod-like bodies scattered in the fibers, built from Z-disc proteins. Centronuclear myopathy shows nuclei that sit in the middle of the fiber instead of at the edge, like immature muscle cells. All three appear in infancy with a floppy baby picture.
Step 3: Place Z-band (myofibrillar) myopathy in a different box.
Z-band myopathy belongs to the myofibrillar myopathy family, where the Z-disc breaks down over time and abnormal protein clumps build up. Unlike the three above, it typically shows up in adulthood with slowly progressive limb or distal weakness, and it is grouped separately from the congenital myopathies in most classifications.
Step 4: Draw the conclusion.
Since three of the four options fit the congenital myopathy definition and the fourth does not, the exception is $Z\ band\ myopathy$.
\[ \boxed{\text{Z Band Myopathy}} \]
A congenital myopathy is a structural muscle disease present from birth, diagnosed by a specific pattern on muscle biopsy, not by fiber necrosis as in a true dystrophy. Three names have carried this label for decades.
Step 2: Walk through the classic three.
Central core disease shows pale, enzyme-poor cores running down the centre of fibers. Nemaline myopathy shows small rod-like bodies scattered in the fibers, built from Z-disc proteins. Centronuclear myopathy shows nuclei that sit in the middle of the fiber instead of at the edge, like immature muscle cells. All three appear in infancy with a floppy baby picture.
Step 3: Place Z-band (myofibrillar) myopathy in a different box.
Z-band myopathy belongs to the myofibrillar myopathy family, where the Z-disc breaks down over time and abnormal protein clumps build up. Unlike the three above, it typically shows up in adulthood with slowly progressive limb or distal weakness, and it is grouped separately from the congenital myopathies in most classifications.
Step 4: Draw the conclusion.
Since three of the four options fit the congenital myopathy definition and the fourth does not, the exception is $Z\ band\ myopathy$.
\[ \boxed{\text{Z Band Myopathy}} \]
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