Vitiligo Etiology and Patient Communication

Amit Pandya, MD: In terms of what causes vitiligo, we know that there are 40 or 50 genes associated with vitiligo. Ninety percent of them are immune-associated genes having to do with T cells and dendritic cells, and 10% are melanocyte-specific genes. When you see these gene abnormalities because the body is attacking, the T cells are against the melanocytic antigens. We think that the actual genetic cause is about 30% of the overall cause. We say that because let’s say you have a twin brother who’s genetically identical to you. If that brother develops vitiligo, you have about a 25% chance of getting vitiligo. That tells us that genes aren’t everything, and that 70% or 75% is environmental, and we haven’t discovered that environmental cause. Is it a virus? Is it a food? Is it an allergen that we haven’t discovered that causes the vitiligo? Perhaps it’s an insect bite, which then epitope spreading then leads to vitiligo. We haven’t figured that out in terms of environmental cause. Both are needed.

However, only 30% of patients with vitiligo have a family history of vitiligo. We know it’s not necessarily like everybody must have family members, but they likely have 1 of the genetic causes, 1 of the 50 genes, and then there’s some environmental trigger that then causes the onset of vitiligo. In terms of the trigger, we sometimes see that if a person gets, for example, a scrape in their skin and then develops vitiligo, they get a sunburn and they get vitiligo, they get a chemical burn from hair dye and then they get vitiligo. There are some triggers that have to do with the environment that we can see, but most of the time we can’t identify the exact environmental trigger that caused the onset of the vitiligo.

Brett King, MD, PhD: It’s a tricky topic, this idea of what caused it or why somebody has it. Patients often want to spend a lot of time around the thing that they believe caused it. How do you approach this conversation with patients who likely have a genetic background, but there’s some other trigger that led to the disease manifesting? How do you explain this to patients?

Amit Pandya, MD: I tell patients that we believe that 70% of the cause is environmental and 30% is genetic, but we haven’t discovered the exact environmental cause for vitiligo. Some things can trigger it, like a scrape or a sunburn. But that doesn’t explain everything, so we’re still doing research on that.

Brett King, MD, PhD: Patients often want to take that trigger and then try to control it as if they could dial back time and erase that the event ever happened. How do you discuss that with them? Do you say, “Well, the horse is out of the barn. It sort of doesn’t matter what led to it happening to begin with”? How do you guide that part of the conversation? Because it’s easy for patients, and understandably, it’s easy for them to get hung up on that point and want to control it.

Amit Pandya, MD: What I tell them is that vitiligo is an immune-mediated disease in which the immune system is attacking the skin. The immune system is present in your lymph nodes, your spleen, your bone marrow. At some point in your life, around the time your vitiligo started, your immune system started creating millions of T cells that we call CD8+ T cells, whose goal in life is only 1 thing: to destroy your melanocytes. Those T cells are circulating in your bloodstream, and we haven’t discovered a way to remove them permanently from your bone marrow, from your blood, without knocking out your entire immune system, which wouldn’t be healthy for you. Unfortunately, you now have these T cells, which is why they’re coming out of the skin. These T cells are attacking the melanocytes. Our goal is to remove them from the skin. But I don’t have a way of removing them from your bloodstream, so you’ll have that risk of developing new lesions if you’re not treating the skin.

Transcript Edited for Clarity