Did you know the lifetime risk for developing alopecia areata is >2%, even with no family history? Alopecia areata is an autoimmune disorder characterized by hair loss on the scalp or other body parts. In people with alopecia areata, the immune system attacks the hair follicles, causing them to shrink and preventing new hair from growing. Studies have shown that people with certain HLA genes are more likely to develop alopecia areata. This suggests that there may be a genetic predisposition for the condition.
What is Alopecia Areata?
Alopecia areata is a health condition that results in massive amounts of hair fall.
Most people with alopecia witness hair fall in small and round patches resulting in a coin-like appearance of bare skin.
While alopecia mostly affects the scalp, it can result in hair fall in other body parts like eyebrows.
It affects as many as 6.8 million people in the United States and 147 million worldwide.
Alopecia is the second most common hair loss condition after androgenetic alopecia and affects men and women equally.
Alopecia isn’t a painful or disabling condition; however, it can change a person's physical appearance, affecting their quality of life and self-esteem.
Most of the research shows that people with alopecia have higher levels of anxiety and depression.
Types of Alopecia
There are two types of alopecia areata:
- Alopecia totalis: Hair loss involves the entire scalp
- Alopecia universalis: Hair loss involves the scalp and body
Research also reports a few rarer forms of alopecia, each with unique hair loss patterns.
What Causes Alopecia?
The role of our immune system is to fight off unwanted invaders that enter our body, like viruses and harmful bacteria.
In some people, the immune system goes into overdrive and starts attacking the healthy cells in the body, resulting in a group of conditions called autoimmune disorders.
Alopecia, one such autoimmune condition, occurs when the immune system starts attacking the hair follicles.
However, it doesn't destroy the hair follicles, so hair regrowth is a possibility.
The reason why the immune system goes into overdrive is complex and not well understood.
It could be a combination of many factors like hormonal imbalances and genetic changes.
Evidence also supports that environmental factors like stress, physical injury, and illness can result in abnormal immune reactions.
Is Alopecia Genetic?
The immune system involvement in alopecia suggests the role of HLA genes in alopecia.
HLA genes to a gene family called the human leukocyte antigen (HLA) complex.
The HLA complex plays a key role in guiding the immune system by helping it differentiate between the body's own proteins and proteins made by foreign invaders.
There are many types of HLA genes, each of which allows the immune system to react to different types of invaders.
Certain changes in these HLA genes can make the immune system confused and result in misidentifying the body's own cells as foreign.
In alopecia, specific HLA gene changes make the hair follicles appear foreign to our immune system.
Other genes involved in inflammatory processes also appear to play a role in alopecia.
Alopecia shares similar genetic roots to other autoimmune conditions.
Therefore, people with alopecia may be at increased risk for conditions like:
- Allergic asthma
- Atopic dermatitis
- Psoriasis
- Vitiligo
- Systemic lupus erythematosus
- Autoimmune thyroid conditions
People with any of these conditions have an increased risk for alopecia as well.
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Inheritance of Alopecia
Several genetic, environmental, and lifestyle factors contribute to alopecia.
As a result, the inheritance pattern is unclear.
However, it is evident that the risk for alopecia is heightened in siblings and children of affected individuals than in the general population.
A family history of other autoimmune conditions also increases the risk of alopecia.
Other Risk Factors for Alopecia
The risk for alopecia increases with:
- A family history of the condition
- Hormonal changes due to pregnancy
- Medical conditions like type 1 diabetes and lupus
- Certain medications
- Prolonged periods of stress
- Poor nutrition
Diagnosis and Treatment of Alopecia
The primary step in diagnosing alopecia areata is a physical exam to see the pattern of hair loss.
Blood tests can also reveal autoimmune disorders.
The doctor may also perform additional tests to reveal any underlying disorder.
The type of test your doctor may order depends on what they may suspect is causing the problem, which may be based on other symptoms.
Some common medications used to treat children 10 years or younger are corticosteroids and minoxidil.
They are also used in adults with patchy alopecia areata
Complete loss of hair is treated with contact immunotherapy, where the goal is to change your immune system so that it stops attacking your hair follicles.
Summary
- Alopecia areata is an autoimmune condition that results in patchy hair loss.
- Alopecia occurs when the immune system mistakenly attacks hair follicles, causing hair fall.
- The HLA group of genes that regulate the immune system plays a role in alopecia. Certain changes in the HLA gene can result in the immune system misidentifying hair follicles as foreign and attacking them.
- Type 1 diabetes, vitiligo, autoimmune thyroid diseases, and systemic lupus erythematosus are some autoimmune conditions that share genetic roots with vitiligo.
- Alopecia can be diagnosed with physical exams and blood tests. There are several medication options used for treatment.
References
- https://medlineplus.gov/genetics/condition/androgenetic-alopecia/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1261195/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5573125/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5097114/
- https://medlineplus.gov/images/PX0001UL_PRESENTATION.jpeg
- https://journals.lww.com/md-journal/Fulltext/2018/08100/HLA_DRB1_polymorphisms_and_alopecia_areata_disease.30.aspx
