biology

Schwartz–Jampel syndrome

Schwartz–Jampel syndrome is a biology 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 Schwartz–Jampel syndrome rather than just read about it. In short: Schwartz–Jampel syndrome (SJS, also known as chondrodystrophic myotonia) is a rare genetic disease caused by a mutation in the perlecan gene (HSPG2) which causes osteochondrodysplasia associated with myotonia. Most people with Schwartz–Jampel syndrome have a nearly normal life expectancy.

Key takeaways

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

Reference excerpt

Schwartz–Jampel syndrome (SJS, also known as chondrodystrophic myotonia) is a rare genetic disease caused by a mutation in the perlecan gene (HSPG2) which causes osteochondrodysplasia associated with myotonia. Most people with Schwartz–Jampel syndrome have a nearly normal life expectancy.

Cause Schwartz–Jampel syndrome is caused by mutations in the HSPG2 gene, which makes the protein perlecan, which is found in muscle and cartilage. Relationships between the disease and perlecan deficiency have been studied. In Schwartz–Jampel syndrome, it is suspected that abnormal perlecan function leads to a deficiency in acetylcholinesterase, an enzyme involved in breaking down the neurotransmitter acetylcholine, which incites muscle contraction. If acetylcholine is not broken down, it can lead to prolonged muscle contraction/stiffening of the muscles (myotonia). The condition is believed to follow an autosomal recessive inheritance pattern, although some reported cases suggest an autosomal dominant inheritance pattern.

Symptoms Some signs and symptoms that are frequently exhibited in patients with SJS include epiphyseal abnormalities, metaphyseal abnormalities, arthrogryposis multiplex congenita, bowing of long bones, a protruding lower lip, full cheeks, a disturbed gait, genu valgum, hip dysplasia, hypertonia, intellectual disability, joint stiffness, low-set posteriorly-rotated ears, metatarsus valgus, micromelia, myotonia, narrow mouth, flat foot, pursed lips, short stature, skeletal dysplasia, trismus, and visual impairment.

Diagnosis Schwartz–Jampel syndrome is diagnosed on the basis of characteristic facial features, skeletal features and myotonia. Blood tests may show elevated serum creatine kinase or aldolase. X-rays, muscle biopsy or electromyography (EMG) may be useful. Genetic testing for the HSPG2 gene may confirm diagnosis.

Treatment There is no cure for Schwartz–Jampel syndrome. Treatment is aimed at reducing muscle stiffness and cramping and may include massage, muscle warming and gradual strengthening exercises. Muscle relaxants or anti-seizure medications, especially carbamazepine, may be used. Eye symptoms such as blepharospasm might be relieved by Botox. Otherwise, a variety of surgical procedures have been found to be effective. Malignant hyperthermia, a potential complication of surgery, is a greater risk for people Schwartz–Jampel syndrome and an important consideration when considering surgery.

Prognosis Most people with Schwartz–Jampel syndrome have a nearly normal life expectancy.

History The syndrome was first described in 1962 by American ophthalmologist Oscar Schwartz and American neuro-ophthalmologist Robert Steven Jampel.

Society In March 2013, there was media coverage of a British 7-year-old boy named Owen, with chronically tense muscles due to SJS, and his three-legged pet dog. They became first-place winners of the 2013 Crufts Kennel Club's annual Friends for Life competition, which "celebrates dogs that have truly earned the title of man’s best friend through bravery, support or companionship". The dog was also awarded The Braveheart Honour in the ceremony of The British Animal Honours in April 2013 (Haatchi the dog). The two are featured in the book Haatchi & Little B (2014, ISBN 125-006-936-X) by Wendy Holden and on Haatchi's Facebook page. In 2016, 9-year-old Owen was featured in a TLC documentary series, Two in a Million, in which he met and formed a friendship with Giovanni, a 7-year-old American boy with SJS.

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with Schwartz–Jampel syndrome

Start with the simplest possible case. Write down what Schwartz–Jampel syndrome claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, 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 Schwartz–Jampel syndrome 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 Schwartz–Jampel syndrome 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 Schwartz–Jampel syndrome

In research: Schwartz–Jampel syndrome appears in biology 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 Schwartz–Jampel syndrome 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: Schwartz–Jampel syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genetic syndromes, Rare diseases, Skeletal disorders, so understanding it makes those chapters shorter.
In everyday life: Look for Schwartz–Jampel syndrome 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 Schwartz–Jampel syndrome in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Schwartz–Jampel syndrome 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 Schwartz–Jampel syndrome out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Schwartz–Jampel syndrome in simple terms?

Why does Schwartz–Jampel syndrome matter?

Because it connects several biology 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 Schwartz–Jampel syndrome?

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 Schwartz–Jampel syndrome.