science

Multi/minicore myopathy

Multi/minicore myopathy is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Multi/minicore myopathy rather than just read about it. In short: Multi/minicore myopathy is a congenital myopathy usually caused by mutations in either the SELENON and RYR1 genes. It is characterised the presence of multifocal, well-circumscribed areas with reduction of oxidative staining and low myofibrillar ATPase on muscle biopsy.

Key takeaways

Multi/minicore myopathy belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Multi/minicore myopathy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Multi/minicore myopathy from memory before moving on to harder problems.

Reference excerpt

Multi/minicore myopathy is a congenital myopathy usually caused by mutations in either the SELENON and RYR1 genes. It is characterised the presence of multifocal, well-circumscribed areas with reduction of oxidative staining and low myofibrillar ATPase on muscle biopsy. It is also known as Minicore myopathy, Multicore myopathy, Multiminicore myopathy, Minicore myopathy with external ophthalmoplegia, Multicore myopathy with external ophthalmoplegia and Multiminicore disease with external ophthalmoplegia.

Presentation

There are four types of minicore myopathy Classical type (75% cases) The usual presentation is in infancy or childhood with hypotonia or proximal weakness. This weakness tends to affect the shoulder girdle and the inner thigh. The other main features are

Failure to thrive due to feeding difficulties Axial muscle weakness, particularly affecting neck and trunk flexors High pitched voice Myopathic facial features A high arched or cleft palate may be present. Later developing features include a progressive scoliosis and respiratory impairment. Ophthalmoplegic form (5–10% cases) This typically presents with weakness of abduction and upward gaze. Ptosis may occur. There is also weakness of the proximal limb muscles. Progressive form with hand involvement (10% cases) The type presents with progressive hand weakness and hypermobility. Hip girdle weakness may be present and exercise induced myalgia is common. Scoliosis and respiratory problems are mild or absent. Antenatal form with arthrogryposis multiplex congenita (10% cases) This diagnosis may be suspected prenatally with reduced fetal movements and polyhydramnios. This typically presents with contractures at birth due to poor foetal movement. Other features include a long head, low set ears and a short neck. The respiratory muscles can be moderately to severely affected and problems with breathing are common.

Genetics The most common causes are mutations in the RYR1 and SELENON genes. In these cases the inheritance is autosomal recessive. Less common recessive mutations causing this condition include those in the TTN, MEGF10 and CACNA1S genes. Automsomal dominant mutations associated with this disease include those in MYH7 and CACNA1S. The pathogenesis is not well understood at present.

Diagnosis

The diagnosis may be suspected on clinical grounds. On blood testing the creatine kinase may be raised. Imaging with ultrasound or MRI will show abnormalities in the affected muscles but these changes are not diagnostic. The diagnostic test is a muscle biopsy. On biopsy type 1 fibres predominate. The sarcomeres are disorganised and the mitochondria depleted. Necrosis and fibrosis are absent. Within the fibres multiple cores are visible.

Differential diagnosis Central core disease Centronuclear myopathy Congenital muscular dystrophy with rigidity of the spine

Management There is presently no curative treatment. Management is supportive. There is an association with malignant hyperthermia and this should be borne in mind if anesthesia is required.

Epidemiology The epidemiology of this condition is not known. Studies have suggested that the prevalence of all congenital myopathies lies between 35 and 50 per million children.

History This condition was first described in 1971.

References

Worked examples

Example 1 — a first encounter with Multi/minicore myopathy

Start with the simplest possible case. Write down what Multi/minicore myopathy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Multi/minicore myopathy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Multi/minicore myopathy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Multi/minicore myopathy

In research: Multi/minicore myopathy appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Multi/minicore myopathy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Multi/minicore myopathy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Rare syndromes, Syndromes affecting the heart, so understanding it makes those chapters shorter.
In everyday life: Look for Multi/minicore myopathy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Multi/minicore myopathy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Multi/minicore myopathy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Multi/minicore myopathy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Multi/minicore myopathy in simple terms?

Why does Multi/minicore myopathy matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Multi/minicore myopathy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Multi/minicore myopathy.