If you are reading this blog, then you are most likely in the 2% of people in the United States with a lifetime risk for alopecia areata (AA). You may have already wondered where this condition comes from and why you have it. We thought we'd help give you a few answers.
Alopecia areata affects both males and females. It can start at any age, and, as you know, most certainly changes the lives of the people who live with it. The key to management and acceptance is education, and that starts with understanding a little about the condition, and answering questions like is alopecia areata hereditary?
The human immune system faces a multitude of tasks. Allergies, for example, are over-reactions to external antigens whereas autoimmune diseases are over-reactions to self antigens.
In the case of alopecia areata, the immune system mistakenly attacks the hair follicle, the organ responsible for hair growth. In AA, the normal hair growth cycle is disrupted even though the follicle itself is not destroyed. The most typical age for onset is in the teens or early twenties, though it can occur before age two and well into the senior years, or any stage in between.
What about the why? Is alopecia areata hereditary? Two very good questions.
Autoimmune diseases can affect anyone, at anytime. Alopecia areata is considered to be an autoimmune disease, although with far less disability and severity than a condition like lupus erythematosus or autoimmune hepatitis.
No one really knows why the immune system disrupts the normal function of hair follicles. Genetics is a possible answer, but certainly not the only factor. Genetics do not explain it all.
Often people with alopecia areata are in a familial gene pool where other autoimmune diseases are evident. But not everybody who gets an autoimmune condition has a family history of abnormal immune responses. You might be the only person in your family. That supports the theory that other environmental factors are also at work in the development of autoimmune diseases and alopecia areata. Those other factors are commonly called "triggers" and can include exposure to trauma, infection, surgery or even the changing hormones of pregnancy. Often the trigger is unknown.
While researchers do know that both genetics and environmental triggers are part of the alopecia areata "puzzle" it's unknown how much each contributes to the AA of a particular individual. AA results from a multiplex of genes, not just one specific gene. There is no known predictor of how many AA genes you inherit, their persistence and how strong the genetic influence is in you. Alopecia areata often skips generations with no predictability.
Demographic studies put the number of people in our general population who have AA at the same time at only 0.05% - 0.1% of the population. These demographic estimates include every type of AA ranging from small, transient patches up to total hair loss (universalis).
In the most recent studies, the average lifetime risk for any individual in the general population to experience any form of AA is close to 2%. In talking to others, remember the essential qualifier phrase "lifetime risk" because 2% of our current population (six million) do not experience AA today. Let's put it another way: you may have read the number six million as in "six million Americans are affected." Most people would read that as meaning that six million people have AA in the USA today when the real prevalence is a small fraction of that.
Researchers consider the alopecia areata disease to be a result of complex genetic and environmental factors. They know that the genetic predisposition to alopecia areata is influenced by a multiplex of genes, not by one gene. Additonally, the strength of the influence of your inherited genes versus your environmental triggers cannot be pre-determined. That's what makes the diagnosis of AA frustrating...it's the not knowing when or if your AA will start or stop or how severe it will be.
According to statistical studies, there is a higher incidence in blood relatives, often estimated at a 1 in 5 chance. However, because the data encompasses very distant blood relatives, many researches regard the real risk as likely much lower than a 1 in 5 chance. Overall, the risk of you having a child with AA is very small indeed.
Alopecia areata can be psychologically shocking. It is understandable to worry about whether you will pass the condition on to your children or if you are likely to develop it if a parent is a sufferer. The answer is a frustrating but small maybe.
There is no straightforward answer to the heredity question. At best, a family history of the condition is a risk factor, but not a reason to panic.