biology

Sabinas brittle hair syndrome

Sabinas brittle hair 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 Sabinas brittle hair syndrome rather than just read about it. In short: Sabinas brittle hair syndrome, also called Sabinas syndrome or brittle hair-mental deficit syndrome, is an autosomal recessive congenital disorder affecting the integumentary system. Signs and symptoms Symptoms include brittle hair, mild mental retardation and nail dysplasia.

Key takeaways

Sabinas brittle hair syndrome belongs to biology; place it in that map before memorising details.
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Connect Sabinas brittle hair syndrome to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sabinas brittle hair syndrome from memory before moving on to harder problems.

Reference excerpt

Sabinas brittle hair syndrome, also called Sabinas syndrome or brittle hair-mental deficit syndrome, is an autosomal recessive congenital disorder affecting the integumentary system.

Signs and symptoms Symptoms include brittle hair, mild mental retardation and nail dysplasia. The syndrome was first observed in Sabinas, a small community in northern Mexico. The principal biochemical features of the illness are reduced hair cystine levels, increased copper/zinc ratio, and presence of arginosuccinic acid in the blood and urine. The key finding is brittle hair with low sulfur content, but alternating dark and light bands under polarizing microscopy, trichoschisis, and absent or defective cuticle are additional important clues for the diagnosis of trichothiodystrophy. Review of literature reveals extensive associated findings in trichothiodystrophy. Amino acid analyses of control hair when compared with those of patients with the Sabinas syndrome showed very striking differences with regard to content of sulphur amino acids. As in previous descriptions of amino acid abnormalities in the trichorrhexis nodosa of arginosuccinicaciduria, there were increases in lysine, aspartic acid, alanine, leucine, isoleucine, and tyrosine. Trichothiodystrophy represents a central pathologic feature of a specific hair dysplasia associated with several disorders in organs derived from ectoderm and neuroectoderm. Trichothiodystrophy or TTD is a heterogeneous group of autosomal recessive disorders, characterized by abnormally sulfur deficient brittle hair and accompanied by ichthyosis and other manifestations. Patients with trichothiodystrophy should have a thorough evaluation for other associated manifestations, including investigation of photosensitivity and DNA repair defects. Because the disease appears to be inherited in an autosomal recessive pattern, detection of low-sulfur brittle hair syndrome is also important for genetic counseling.

Genetics Sabinas brittle hair syndrome is inherited as an autosomal recessive genetic trait. In a study by Howell et al. patients were located and studied by means of complete histories and physical examinations, analyses of serum trace metals, ceruloplasmin concentration, urine and serum amino acids, and routine metabolic urine screens. In addition, serum and urine luteinizing hormone (LH) and follicle-stimulating hormone (FSH) values were determined, and were interpreted in conjunction with total plasma estrogen, estradiol, and testosterone levels. Close examination demonstrated the scalp hairs were very brittle, coarse, wiry in texture, and broke off quite easily with mechanical trauma such as combing and brushing. Some hairs could be visualized in their follicles, which were broken off at the skin line. Most patients had accompanying hyperkeratosis (thickening of the skin) of moderate degree on exposed surfaces. Maxillary hypoplasia (midfacial retrusion) was significant in many patients. The brittle, short hair, reduced eyelashes, crowded teeth, and dull appearance created a characteristic facial appearance. Post-pubertal patients had development of secondary sexual characteristics consistent with their age, except for sparse pubic escutcheons. All cases studied demonstrated some degree of mental deficiency; I.Q.'s ranged between 50 and 60. A deficiency in eye–hand coordination was also noted.

Diagnosis The easiest way to test for this condition is through genetic testing. Several methods can be used for genetic testing that can help identity this condition,

Molecular genetic tests (or gene tests) study single genes or short lengths of DNA to identify mutations and variations that can help lead to a genetic disorder. Chromosomal genetic tests help investigate whole chromosomes or long lengths of DNA to see if there are bigger genetic changes, for example, an extra copy of a chromosome that can help cause a genetic condition. Biochemical genetic tests study the activity level and amount level of proteins; abnormalities in either can indicate changes to the DNA and result in a genetic disorder.

Management Although there has been no conclusive evidence on medications to manage the disorder, many organizations help with several aspects on living with the chronic condition, not only for the affected but also for the loved ones around them. With services like Global Genes helping contribute to this.

References

Further reading Itin P., Pittelkow M., Trichothiodystrophy: Review of sulfur-deficient brittle hair syndromes and association with the ectodermal dysplasias[1]. Journal of the American Academy of Dermatology, Volume 22, Issue 5, Pages 705–717 Rare Disorders: All you need to know. Trichothiodystrophy[2]. Copyright © 2005 Rare-Disorders.com Sabinas brittle hair syndrome is a form of nonphotosensitive trichothiodystrophy; Brittle hair and mental deficit at NIH's Office of Rare Diseases

External links

Illustrations

Worked examples

Example 1 — a first encounter with Sabinas brittle hair syndrome

Start with the simplest possible case. Write down what Sabinas brittle hair 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 Sabinas brittle hair 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 Sabinas brittle hair 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 Sabinas brittle hair syndrome

In research: Sabinas brittle hair 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 Sabinas brittle hair 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: Sabinas brittle hair syndrome is common in secondary-school and first-year university syllabi. It links to neighbouring topics Autosomal recessive disorders, Conditions of the skin appendages, Rare diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Sabinas brittle hair 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 Sabinas brittle hair syndrome in 20 minutes

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Close the page and write down what Sabinas brittle hair syndrome means in your own words.
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Frequently asked questions

What is Sabinas brittle hair syndrome in simple terms?

Sabinas brittle hair syndrome, also called Sabinas syndrome or brittle hair-mental deficit syndrome, is an autosomal recessive congenital disorder affecting the integumentary system. Signs and symptoms Symptoms include brittle hair, mild mental retardation and nail dysplasia.

Why does Sabinas brittle hair 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 Sabinas brittle hair 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 Sabinas brittle hair syndrome.