The genetically programmed hair growth cycle and alopecia: what is there to know?

    June 2006 in “Expert Review of Dermatology
    Desmond J. Tobin
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    TLDR The document concludes that hair loss is complex, affects many people, has limited treatments, and requires more research on its causes and psychological impact.
    The 2006 document provides a comprehensive overview of hair follicle biology, the hair growth cycle, and common forms of alopecia. It explains the hair follicle as a mini organ with a cycle consisting of anagen, catagen, telogen, and exogen phases, influenced by systemic and local factors. The review emphasizes the dermal papilla's role in regulating the hair cycle, the bulge activation hypothesis for stem cell stimulation, and the complex role of androgens in hair growth. It also discusses genetic programming of hair growth patterns, racial and ethnic differences, and the influence of societal expectations. Male pattern alopecia (MPA) is identified as the most common hair loss condition, affecting a significant percentage of men by age 70, with treatments like minoxidil and finasteride available. Female pattern alopecia (FPA) is characterized by diffuse hair thinning, with limited treatment options, and the importance of considering iron status in affected women is noted. Alopecia areata (AA) is described as an immune-mediated condition with no cure, and telogen effluvium (TE) as a condition with excessive hair shedding due to various triggers. The document underscores the psychological impact of hair loss and the need for more research into genetic regulation and the aging process in alopecia.
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