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Hair and hairy scalp
Published in Richard Ashton, Barbara Leppard, Differential Diagnosis in Dermatology, 2021
Richard Ashton, Barbara Leppard
This is the commonest cause of discrete hair loss in both children and adults. The trigger is often a stressful event and alopecia areata itself is often very distressing especially if it affects a large area. There is no redness or scaling of the underlying scalp. There may be one or several bald patches on the scalp or on any other hairy area (e.g. eyebrows, eyelashes, beard). The hair loss is sudden. While the disease is active, exclamation mark (!) hairs will be seen around the edge of the bald patches. These are short broken off hairs which are thicker and darker at the broken off end. Only pigmented hairs are affected by alopecia areata, so normal white/grey hairs will remain in the middle of a bald area. It can take months or years to grow back and new patches may develop. It will usually regrow white or blonde initially (Fig 3.07), but goes back to its original colour after 6–8 weeks.5% of individuals affected will have total scalp hair loss (alopecia totalis), or total loss of scalp and body hair (alopecia universalis). Alopecia areata is a common auto-immune disease and can occur at any age and in any ethnic group. It is worth asking about a family history of autoimmune disease and checking the HbA1c level and an auto immune profile including thyroid antibodies.
Biology of the Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Bleaching, or lightening of the hair color, is common in both brunette and blonde individuals who expose their hair to ultraviolet radiation (94). Brunette hair tends to develop reddish hues due to photooxidation of melanin pigments, while blonde hair develops photoyellowing. The yellow discoloration is due to photodegradation of cystine, tyrosine, and tryptophan residues within the blonde hair shaft (95). This points to a need for the development of photoprotective conditioning products for the hair.
Genetic Principles
Published in Gail S. Anderson, Biological Influences on Criminal Behavior, 2019
We often ask, why don’t recessive alleles that sometimes cause problems, such as disease and antisocial behavior, die out? Let us look first at a very harmless example. There are many more dark-haired people than blonds in the world. As people travel and emigrate, they mix everywhere. Despite the fact that blond hair is recessive to dominant dark hair, it does not die out. There are still blond people. This is because there is no downside to being blond; in other words, there is no selective advantage for either hair color. So, if a dark-haired person mates with a blond, they could have blond or brunette children. If two dark-haired people mate, the children could still be either, depending on the genotypes of the parents. If both are heterozygous, then the children could be blond. Blond is not lost, just hidden for a generation—remember the purple and white flowers.
Oculocutaneous albinism type 1B associated with a functionally significant tyrosinase gene polymorphism detected with Whole Exome Sequencing
Published in Ophthalmic Genetics, 2021
Rodrigo Mendez, Sumaiya Iqbal, Sebastián Vishnopolska, Cinthia Martinez, Glenda Dibner, Rocio Aliano, Jonathan Zaiat, Germán Biagioli, Cecilia Fernandez, Adrian Turjanski, Arthur J Campbell, Graciela Mercado, Marcelo A. Marti
The proband was a 17-year-old boy affected with OCA. His parents were unrelated and they reported no family history of albinism (Figure 1a). Pigmentation of the skin and hair was light but considered normal blond. Ophthalmological examination showed reduced 20/70 visual acuity in both eyes with the maximum correction. He presented bilateral horizontal nystagmus, exacerbated with luminosity and eye movements. Parents’ eye examination was normal. The biomicroscopy showed a zone of iridian atrophy that generated a mixed macroscopic color pattern with a predominance of brown and iris retroillumination (Figure 1b). The dilated-eye exam was typical, the absence of pigment in the pigmentary epithelium and clear visualization of the choroidal vessels are observed. The macula was altered in its morphology: it had less pigment and decreased characteristic foveolar brightness. These macular findings were confirmed by Optical Coherence Tomography (OCT) which showed foveal hypoplasia. The flash visual potential (VEP) was abnormal demonstrating a misrouting of the optic pathway. Karyotype analysis was 46 XY (20).
Ocular findings of albinism in DYRK1A-related intellectual disability syndrome
Published in Ophthalmic Genetics, 2020
Julia Ernst, Michelle L. Alabek, Amgad Eldib, Suneeta Madan-Khetarpal, Jessica Sebastian, Aashim Bhatia, Alkiviades Liasis, Ken K. Nischal
Ocular features consistent with albinism in our case include iris trans-illumination defect, hypo-pigmented fundus, and crossed asymmetry evident in both pattern and flash VEPs. Our patient did not have nystagmus, which has been previously reported in some cases of albinism (14,17,18). Extra-ocular features consistent with albinism in our case include blonde hair and fair skin tone. Revisiting the family history in light of this suspected diagnosis revealed that her mother has brown hair and less fair skin tone, her father is reported to have blonde hair and slightly less fair skin tone, and her maternal half-brother is reported to have brown hair and medium skin tone. None of these individuals are noted to have ocular features consistent with albinism; however, formal ophthalmologic evaluation was not completed. It is difficult to conclude if the case’s blonde hair and fair skin tone are related to the suspected diagnosis of albinism, or if these fall within the spectrum of the family history.
Hair dye and risk of skin sensitization induction: a product survey and quantitative risk assessment for para-phenylenediamine (PPD)
Published in Cutaneous and Ocular Toxicology, 2020
Kevin M. Towle, Ruth Y. Hwang, Ernest S. Fung, Dana M. Hollins, Andrew D. Monnot
Out of the 24 analysed samples, 22 hair dye products contained PPD at a detectable level greater than the reporting limit (25 ppm). The shade-specific median concentrations of PPD (as reported by the analytical laboratory) were 3600 ppm (range: 41–6700 ppm) for black hair dyes, 1300 ppm (range: <25–5400 ppm) for brown hair dyes, and 445 ppm (range: <25–600 ppm) for blonde hair dyes (Table 2). These ppm concentrations of PPD correspond to the following percent PPD concentrations: 0.0041% to 0.67% for black hair dyes, <0.0025% to 0.54% for brown hair dyes, and <0.0025% to 0.06% for blonde hair dyes. These concentrations represent the hair dye mixture (combination of colour component and developer component). There was a statistically significant difference in PPD concentrations between black (p = 0.0028) and brown (p = 0.0485) hair dyes in comparison to blonde hair dyes. There was no statistically significant difference (p values = 0.4959) in PPD concentrations between black and brown hair dyes.