science

Sensenbrenner syndrome

Sensenbrenner syndrome 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 Sensenbrenner syndrome rather than just read about it. In short: Sensenbrenner syndrome (OMIM #218330) is a rare (less than 20 cases reported by 2010) ciliopathy first described by Judith A. Sensenbrenner in 1975.

Key takeaways

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

Reference excerpt

Sensenbrenner syndrome (OMIM #218330) is a rare (less than 20 cases reported by 2010) ciliopathy first described by Judith A. Sensenbrenner in 1975. It is inherited in an autosomal recessive fashion, and is caused by a loss of function mutation in one of three genes: IFT122, IFT43, and WDR35. It is also known as Sensenbrenner–Dorst–Owens syndrome, Levin syndrome I and cranioectodermal dysplasia (CED)

Signs and symptoms

dolichocephaly (with or without sagittal suture synostosis) microcephaly brachydactyly narrow thorax dwarfism/growth retardation prominent epicanthal folds hypodontia and/or microdontia sparse, slow-growing, hyperpigmented, fine hair nail dysplasia hypohydrosis chronic kidney disease heart defects liver fibrosis rhizomelia visual field defects with or without abnormal electroretinography.

photophobia hypoplasia of the posterior corpus callosum aberrant calcium homeostasis

Two fetuses of 19 and 23 weeks gestation have also been reported. They showed acromesomelic shortening, craniofacial characteristics with absence of craniosynostosis, small kidneys with tubular and glomerular microscopic cysts, persistent ductal plate with portal fibrosis in the liver, small adrenals, an enlarged cisterna magna and a posterior fossa cyst.

Cause

The gene IFT122 is located on the long arm of chromosome 3 (3q21-3q24). The gene lies on the Watson (plus) strand and is 80,047 bases in length. The encoded protein has 1241 amino acids and a predicted weight of 141.825 kilodaltons (kDa). It is a member of the WD repeat protein family. WDR35 is also a member of the WD repeat protein family. The gene is located on the short arm of chromosome 2 (2p24.1–2p24.3) The gene lies on the Crick (minus) strand and is 79,745 bases in length. The encoded protein is 1181 amino acids in length and its predicted molecular weight is 133.547 kilodaltons. The gene IFT43 lies on the Watson (plus) strand of the long arm of chromosome 14 (14q24.3). A mouse model for IFT122 has been created. Mutants deficient in IFT122 show multiple developmental defects (many are lethal), including exencephaly, situs viscerum inversus, delay in turning, hemorrhage and defects in limb development. In the node, primary cilia were absent or malformed in homozygous mutant and heterozygous embryos, respectively. Impairment of the Sonic hedgehog pathway was apparent in both neural tube patterning (expansion of motoneurons and rostrocaudal level-dependent contraction or expansion of the dorsolateral interneurons) and limb patterning (ectrosyndactyly).

Pathophysiology The IFT machinery is organized in two structural complexes — A and B. These complexes are involved in the coordinated movement of macromolecular cargo from the basal body along axonemal microtubules to the cilium tip and back again. The anterograde movement of IFT particles out to the distal tip of cilia and flagella is driven by kinesin-2 while the retrograde movement of particles back to the cell body is driven by cytoplasmic dynein 1b/2 The IFT-A protein complex is involved in retrograde ciliary transport. Disruption of IFT43 disturbs transport from the ciliary tip to the base. Anterograde transport in the opposite direction remains normal resulting in accumulation of the IFT complex B proteins in the ciliary tip.

Pathology The visual defects are due to photoreceptor dystrophy. The chronic kidney failure is due to tubulointerstitial nephropathy. The liver fibrosis is secondary to ductal plate malformation.

References

External links

Illustrations

Profile view of patient, showing prominent forehead and dolichocephaly

Worked examples

Example 1 — a first encounter with Sensenbrenner syndrome

Start with the simplest possible case. Write down what Sensenbrenner syndrome 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 Sensenbrenner 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 Sensenbrenner 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 Sensenbrenner syndrome

In research: Sensenbrenner syndrome 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 Sensenbrenner 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: Sensenbrenner syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ciliopathy, Rare syndromes, so understanding it makes those chapters shorter.
In everyday life: Look for Sensenbrenner 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 Sensenbrenner syndrome in 20 minutes

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

Frequently asked questions

What is Sensenbrenner syndrome in simple terms?

Sensenbrenner syndrome (OMIM #218330) is a rare (less than 20 cases reported by 2010) ciliopathy first described by Judith A. Sensenbrenner in 1975.

Why does Sensenbrenner syndrome 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 Sensenbrenner 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 Sensenbrenner syndrome.