biology

Spondyloepiphyseal dysplasia congenita

Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita rather than just read about it. In short: Spondyloepiphyseal dysplasia congenita (SEDc, also known as Spranger-Wiedemann disease) is a type of autosomal dominant dwarfism caused by mutations in the COL2A1 gene. Spondyloepiphyseal dysplasia congenita is present in 1 in 100,000 births, though many children are stillborn, premature, or die shortly after birth.

Key takeaways

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Reference excerpt

Spondyloepiphyseal dysplasia congenita (SEDc, also known as Spranger-Wiedemann disease) is a type of autosomal dominant dwarfism caused by mutations in the COL2A1 gene. Spondyloepiphyseal dysplasia congenita is present in 1 in 100,000 births, though many children are stillborn, premature, or die shortly after birth. This disorder is characterized by delayed ossification, particularly of the spine and the proximal ends of long bones (epiphyses).

Presentation Phenotypes of spondyloepiphyseal dysplasia congenita vary. Defining features include short stature, with a short spine and neck, a barrel chest, and normal-sized hands and feet. This type of dwarfism is characterized by a normal spinal column length relative to the femur bone. Adult height ranges from 0.9 meters (35 inches) to just over 1.4 meters (55 inches). Curvature of the spine (such as kyphoscoliosis and lordosis) progresses during childhood and can cause problems with breathing. Changes in the spinal bones (vertebrae) in the neck may also increase the risk of spinal cord damage. Other skeletal signs include flattened vertebrae (platyspondyly), a hip joint deformity in which the upper leg bones turn inward (coxa vara), and an inward- and downward-turning foot (called clubfoot). Decreased joint mobility and arthritis often develop early in life. Medical texts often state a mild and variable change to facial features, including cheekbones close to the nose appearing flattened, although this appears to be unfounded. Some infants are born with a cleft palate. Severe nearsightedness (high myopia) is sometimes present, as are other eye problems that can affect vision such as detached retinas. About one-quarter of people with this condition have mild to moderate hearing loss.

Causes

Spondyloepiphyseal dysplasia congenita is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. The protein made by this gene forms type II collagen, a molecule found mostly in cartilage and in the clear gel that fills the eyeball (the vitreous). Type II collagen is essential for the normal development of bones and other connective tissues. Mutations in the COL2A1 gene interfere with the assembly of type II collagen molecules, which prevents bones from developing properly and causes the signs and symptoms of this condition. Spondyloepiphyseal dysplasia congenita is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to cause the disorder.

Management There is no treatment for the underlying condition. Supportive/symptomatic treatment is based on the traits present in each person with the condition.

Notable people Michael Dunn, Oscar- and Tony-nominated American actor, The Wild Wild West, Star Trek Warwick Davis, English actor and TV presenter, Willow, Return of the Jedi, Leprechaun film series. His two children also have SED. Lenny Rush, English actor, Am I Being Unreasonable? Natalia Grace, Ukrainian-born American with dwarfism, The Curious Case of Natalia Grace Alexander Katan, Dutch Jewish accountant, teacher, and translator who was murdered by the Nazis during the Holocaust, photos of him were notoriously on display in various museums.

References

Spranger: Bone Dysplasias, Urban & Fischer 2002, ISBN 3-437-21430-6

Further reading GeneReviews/NIH/NCBI/UW entry on X-Linked Spondyloepiphyseal Dysplasia Tarda OMIM entries on X-Linked Spondyloepiphyseal Dysplasia Tarda

External links

Worked examples

Example 1 — a first encounter with Spondyloepiphyseal dysplasia congenita

Start with the simplest possible case. Write down what Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita

In research: Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita 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: Spondyloepiphyseal dysplasia congenita is common in secondary-school and first-year university syllabi. It links to neighbouring topics Autosomal dominant disorders, Collagen disease, Rare diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Spondyloepiphyseal dysplasia congenita 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.
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Frequently asked questions

What is Spondyloepiphyseal dysplasia congenita in simple terms?

Why does Spondyloepiphyseal dysplasia congenita 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 Spondyloepiphyseal dysplasia congenita?

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 Spondyloepiphyseal dysplasia congenita.