Woolly hair

Key takeaways

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

Reference excerpt

Woolly hair is a difficult to brush hair, usually present since birth and typically most severe in childhood. It has extreme curls and kinks, occurs in black people and is distinct from kinky hair. The hairs come together to form tight locks, unlike in kinky hair, where the hairs remain individual. Woolly hair can be generalised over the whole scalp, when it tends to run in families, or it may involve just part of the scalp as in woolly hair nevus. The presence of woolly hair may indicate other problems such as with the heart in Naxos–Carvajal syndrome. Diagnosis is suspected by its general appearance and confirmed by scanning electron microscopy. The condition is rare. Alfred Milne Gossage coined the term woolly hair in 1908. Edgar Anderson distinguished woolly hair from kinky hair in 1936.

Discovery Alfred Milne Gossage coined the term woolly hair to describe the sign in 18 members in three or four generations of a European family in Lowestoft, England, in 1908. He thought it resembled kinky hair, possibly from a Mexican ancestor in that family. He described a dominant inheritance in several members with thick skin of palms and soles, curly hair, and two different coloured eyes, and sent them to William Bateson. Edgar Anderson distinguished woolly hair from Afro-hair in 1936. In 1974 Hutchinson's team classified woolly hair as hereditary woolly hair (autosomal dominant), familial woolly hair (autosomal recessive), and woolly hair nevus. Woolly hair was found in Naxos syndrome, first described in 1986 in Naxos, Greece, and was noted in Carvajal syndrome, first described in 1998, in Ecuador.

Cause Woolly hair may run in families and either occur on its own, or as part of a syndrome.

Hereditary woolly hair

Hereditary woolly hair is autosomal dominant.

Familial woolly hair Familial woolly hair is autosomal recessive. It may be part of a syndrome such as Naxos syndrome, due to passing on of mutations in the JUP gene. When part of Carvajal syndrome, it is due the passing of mutations of the Desmoplakin gene. The two syndromes caused by two different genes, are considered as one entity; Naxos–Carvajal syndrome.

Woolly hair nevus The woolly hair of a woolly hair nevus is in a circumscribed area of the scalp, appears in infancy and does not run in families. It likely represents a mosaic RASopathy.

Signs and symptoms Woolly hair is typically very curly, kinky and characteristically impossible to brush. It can be generalised over the whole scalp, or involve just part of the scalp, and occurs in non-black people. The hairs come together to form tight locks, whereas in kinky hair the hairs remain individual. The hairs typically remain shorter than 12 centimetres (4.7 in) and may be slightly lighter in colour. Woolly hair nevus is a localised area of woolly hair, which may occur on its own, or appear as dark twisted and kinking hair in an adult. Half of people with woolly hair nevus have a warty skin lesion on the same side of the body. It may be associated with eye problems such as two different coloured eyes or strands of tissue across the pupil of the eye. Other associations include ear problems, kidney disease, tooth decay, impairment of bone growth, and skin lesions. Generalised woolly hair is typically seen in Naxos–Carvajal syndrome (with heart involvement), Noonan syndrome, and cardiofaciocutaneous syndrome.

Diagnosis Diagnosis is suspected by its general appearance and confirmed by scanning electron microscopy. Microscopy, trichoscopy and dermoscopy also play a role. The hair strand typically has a smaller diameter, is ovoid on cross-section and exhibits abnormal twisting. The hair shaft also has weak points and alternating dark and light bands. The hair shaft is characteristically of a "snake crawl appearance". Dermoscopy may be required to recognise skin signs.

Outcome The condition may improve in adulthood.

Epidemiology The condition is rare.

Illustrations

Worked examples

Example 1 — a first encounter with Woolly hair

Start with the simplest possible case. Write down what Woolly hair 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 Woolly hair 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 Woolly hair 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 Woolly hair

In research: Woolly hair 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 Woolly hair 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: Woolly hair is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hair diseases, Rare diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Woolly hair 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.

How to study Woolly hair in 20 minutes

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

Frequently asked questions

What is Woolly hair in simple terms?

Woolly hair is a difficult to brush hair, usually present since birth and typically most severe in childhood. It has extreme curls and kinks, occurs in black people and is distinct from kinky hair.

Why does Woolly hair 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 Woolly hair?

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 Woolly hair.