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Genetic Causes of Baldness

Alopecia is the medical term for hair loss. Pattern baldness, androgenetic alopecia, is the most common type of baldness, affecting both men and women. Heredity likely plays a key role in this form of permanent hair loss. In order to determine the type of baldness you are experiencing, your doctor will likely examine the pattern associated with your hair loss in addition to performing a complete medical and family history. If your hair loss is genetic, it is not because too much hair is falling out, rather because of your body's inability to produce more hair.

  1. Hair Growth Cycle

    • Hair growth initiates from hair follicles under the skin. Normally, each strand of your hair undergoes a period of two to six years of hair growth, followed by a resting stage of several months before falling out. After the hair strand is shed, a new hair grows in its place. It is estimated that you lose between 50 and 100 hair strands daily. When baldness occurs, each successive hair growth cycle is shorter, making the hair finer and shorter.

    Symptoms in Men and Women

    • Pattern baldness occurs differently in men and women. Men usually experience a thinning hairline and baldness on the top of the head. This may conclude in complete baldness. Women who experience pattern baldness commonly have thinning all over the head, rarely resulting in complete baldness. Your genetic make-up plays a key role in your risk for and extent of baldness, age of onset and rate of hair loss. Genetic baldness requires the presence of androgens, a genetic predisposition, and time for dihydrotestosterone (DHT) to degrade hair follicles.

    Androgens

    • Researchers have determined that male-pattern and female-pattern baldness is related to androgen hormones, with DHT being the source of most pattern baldness. The androgen receptor (AR) gene is responsible for sending instructions necessary to create a protein called an androgen receptor. Androgen receptors help the body respond appropriately to androgens, including DHT. If variations in the AR gene exist, your risk of genetic baldness increases.

    Genes

    • The AR gene is the gene most closely related to genetic baldness and the major determinant of onset. Another type of baldness, alopecia areata, has recently been associated with eight genes that contribute to this form of baldness. However, just because you have the genes for baldness doesn't mean you will lose your hair for sure. Often a trigger -- environmental factors, stress, age or hormone levels -- is required to permit the baldness genes to express. Baldness is often associated with the mother's side of the family, but the complexity of genetic hair loss may actually have contributing factors from both the mother and the father. It is believed that genes that make you susceptible to baldness are autosomal -- not linked to male or female.

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