The biology of hair diversity

• Published in: International journal of cosmetic science 2013-08, Vol.35 (4), p.329
• Main Authors: Westgate, Gillian E, Botchkareva, Natalia V, Tobin, Desmond J
• Format: Article
• Language: English
• Subjects: Alopecia; Baldness; Females; Genetics; Hair; Hair loss; Pigmentation
• ISSN: 0142-5463; 1468-2494

Synopsis Hair diversity, its style, colour, shape and growth pattern is one of our most defining characteristics. The natural versus temporary style is influenced by what happens to our hair during our lifetime, such as genetic hair loss, sudden hair shedding, greying and pathological hair loss in the various forms of alopecia because of genetics, illness or medication. Despite the size and global value of the hair care market, our knowledge of what controls the innate and within-lifetime characteristics of hair diversity remains poorly understood. In the last decade, drivers of knowledge have moved into the arena of genetics where hair traits are obvious and measurable and genetic polymorphisms are being found that raise valuable questions about the biology of hair growth. The recent discovery that the gene for trichohyalin contributes to hair shape comes as no surprise to the hair biologists who have believed for 100 years that hair shape is linked to the structure and function of the inner root sheath. Further conundrums awaiting elucidation include the polymorphisms in the androgen receptor (AR) described in male pattern alopecia whose location on the X chromosome places this genetic contributor into the female line. The genetics of female hair loss is less clear with polymorphisms in the AR not associated with female pattern hair loss. Lifestyle choices are also implicated in hair diversity. Greying, which also has a strong genetic component, is often suggested to have a lifestyle (stress) influence and hair follicle melanocytes show declining antioxidant protection with age and lowered resistance to stress. It is likely that hair research will undergo a renaissance on the back of the rising information from genetic studies as well as the latest contributions from the field of epigenetics. Résumé La diversité des cheveux, leur style, leur couleur, leur forme et leur courbe de croissance sont parmi les caractéristiques qui nous déterminent les plus. Le style naturel comparé au style temporaire est influencé par ce qui arrive à nos cheveux au cours de notre vie, comme la perte génétique de cheveux, perte soudainede cheveux, le vieillissement et la perte pathologiquede cheveux dans les différentes formes d'alopécie due à la génétique, la maladie ou des médicaments. En dépit de la taille et de la valeur globale du marché des soins capillaires, notre connaissance de ce qui contrôle les caractéristiques innées et exogène de la diversité des cheveux reste li