What is Psoriasis and How Do You Get It?
Psoriasis is a chronic skin condition characterized by itchy scales, inflammation, and redness, most commonly affecting the scalp, knees, elbows, hands, and feet.
According to a study, approximately 7.4 million people in the United States were living with psoriasis in 2013.
Psoriasis is an autoimmune disease wherein immune cells in your blood mistakenly identify newly produced skin cells as foreign invaders and attack them. This can lead to the overproduction of new skin cells beneath the surface of your skin.
These new cells migrate to the surface, displacing existing skin cells and causing the scales, itching, and inflammation associated with psoriasis.
Genetics almost certainly plays a role. Continue reading to learn more about the genetic factors in the development of psoriasis.
Is There a Link Between Genetics and Psoriasis?
According to the National Psoriasis Foundation (NPF), psoriasis typically appears between the ages of 15 and 35, though it can occur at any age. For example, approximately 20,000 children under the age of 10 are diagnosed with psoriasis each year.
Psoriasis can manifest in individuals with no family history of the disease, but having a family member with psoriasis does increase your risk. If one of your parents has psoriasis, you have about a 10 percent chance of developing it. If both of your parents have the condition, your risk increases to 50 percent. Approximately one-third of people diagnosed with psoriasis have a relative who also has the condition.
Researchers investigating the genetic causes of psoriasis start with the premise that the condition originates from an issue with the immune system. Studies on psoriatic skin reveal large numbers of immune cells producing inflammatory molecules known as cytokines. Additionally, psoriatic skin is associated with gene mutations known as alleles.
In the early 1980s, researchers hypothesized that a specific allele might be responsible for inheriting the disease. Later studies identified the allele HLA-Cw6, but found that its presence alone was not sufficient to cause psoriasis. More recent research indicates that further investigation is needed to understand the relationship between HLA-Cw6 and psoriasis fully.
Advanced genetic techniques have led to the identification of approximately 25 different regions in human genetic material (the genome) that may be associated with psoriasis. As a result, genetic studies now offer an indication of an individual’s risk for developing the condition. However, the exact link between these genes and psoriasis is not yet fully understood.
Psoriasis involves a complex interaction between the immune system and the skin, making it challenging to discern cause and effect. While recent genetic findings have provided valuable insights, the precise mechanisms triggering psoriasis outbreaks and the method by which the disease is inherited remain unclear.
What Are Other Contributing Factors to Psoriasis?
Most individuals with psoriasis experience periodic outbreaks or flare-ups followed by periods of remission. Approximately 30 percent of those with psoriasis also suffer from joint inflammation resembling arthritis, known as psoriatic arthritis.
Environmental factors that may trigger the onset or exacerbation of psoriasis include:
- Stress
- Cold and dry weather
- HIV infection
- Certain medications, such as lithium, beta-blockers, and antimalarials
- Withdrawal from corticosteroids
Injury or trauma to the skin can sometimes become a site for a psoriasis flare-up. Infections, particularly strep throat in young people, are also reported as triggers for psoriasis, according to the National Psoriasis Foundation (NPF).
Individuals with psoriasis are more likely to develop certain comorbidities compared to the general population. For example, a study on women with psoriasis revealed that approximately 10 percent of the participants also developed inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis.
People with psoriasis have an increased incidence of:
- Lymphoma
- Heart disease
- Obesity
- Type 2 diabetes
- Metabolic syndrome
- Depression and suicidal ideation
- Alcohol consumption
- Smoking
Can Gene Therapy Be Used to Treat Psoriasis?
While gene therapy is not currently available as a treatment for psoriasis, research into the genetic causes of the disease is expanding. One particularly promising discovery identified a rare gene mutation linked to psoriasis.
The gene mutation, known as CARD14, produces plaque psoriasis when exposed to an environmental trigger such as an infection. Plaque psoriasis is the most common form of the disease. This finding established a connection between the CARD14 mutation and psoriasis.
Researchers also identified the CARD14 mutation in two large families, both of which had numerous members affected by plaque psoriasis and psoriatic arthritis.
This discovery is one of several recent findings that offer hope that gene therapy may one day be able to help people living with psoriasis or psoriatic arthritis.
How Is Psoriasis Traditionally Treated?
For mild to moderate cases of psoriasis, dermatologists typically recommend topical treatments such as creams or ointments. These can include:
- Anthralin
- Coal tar
- Salicylic acid
- Tazarotene
- Corticosteroids
- Vitamin D
For more severe cases, your doctor may prescribe phototherapy in addition to more advanced systemic or biologic medications, which are taken orally or by injection.