Bullous pemphigoid is not a hereditary disease. It is an acquired autoimmune condition, meaning the immune system mistakenly attacks healthy tissue rather than the condition being passed down through families. That said, certain genetic variations can make some people more susceptible to developing it, which is why the question comes up. Having a family member with bullous pemphigoid does not mean you will get it, and familial cases are extremely rare in the medical literature.
Why It’s Autoimmune, Not Inherited
Bullous pemphigoid (BP) develops when the immune system produces antibodies that attack proteins responsible for holding the outer layer of skin to the layers beneath it. Two proteins are the main targets: one is a transmembrane protein that anchors skin cells to the basement membrane, and the other is an intracellular protein that connects the cell’s internal structure to that same anchoring system. Together, these proteins maintain the bond between the epidermis and the dermis.
When antibodies attack these proteins, that bond weakens. Fluid collects between the skin layers, forming the large, tense blisters that define the condition. About 90% of BP patients have antibodies targeting a specific region of the transmembrane protein. This is a process driven by the immune system going haywire, not by a gene mutation being inherited from a parent.
Genetic Susceptibility Is Real but Limited
While BP itself isn’t inherited, your genes can influence how likely you are to develop it. Specific variations in HLA genes, which help the immune system distinguish the body’s own cells from foreign invaders, are found more often in people with BP than in the general population. A study of Brazilian patients found that carrying certain HLA variants increased the risk of developing BP anywhere from roughly 4 to 8 times compared to people without those variants. The highest risk was linked to one particular HLA variant, which was present in about 12% of BP patients but fewer than 2% of healthy controls.
These are susceptibility genes, not destiny genes. Carrying one of these variants doesn’t mean you’ll develop BP. It means your immune system may be slightly more prone to the type of misfiring that causes it, especially if the right environmental trigger comes along. Many people carry these variants and never develop any autoimmune blistering disease. The exact etiology of BP remains unclear, but researchers describe it as influenced by both genetic and environmental factors working together.
What Actually Triggers It
If genetics loads the gun, environmental factors pull the trigger. The most well-documented triggers are medications. A systematic review identified dozens of drugs with likely or probable associations with BP. The strongest evidence points to a class of diabetes medications called gliptins (DPP-4 inhibitors), certain cancer immunotherapy drugs (PD-1 and PD-L1 inhibitors), loop diuretics like furosemide, and penicillin-based antibiotics. Some common over-the-counter medications like ibuprofen also appear on the list, though with varying levels of evidence.
Other reported triggers include certain vaccines and UV light therapy. In many cases, though, no specific trigger is ever identified. The condition simply appears, most often in older adults. The median age at diagnosis is 80, and about 61% of patients are women. BP is uncommon overall, with a global incidence of roughly 34 cases per million people per year, though rates vary by region. In Europe, the figure is closer to 10 per million.
How It’s Diagnosed
BP typically shows up as multiple firm, fluid-filled blisters on the skin, often alongside intensely itchy red or hive-like patches, smaller vesicles, and crusted areas where blisters have broken open. The gold standard for confirming the diagnosis is a skin biopsy taken from the edge of a blister or the area just next to it. A technique called direct immunofluorescence looks for a specific pattern: a linear band of immune proteins deposited along the junction where the epidermis meets the dermis. That pattern is the hallmark of BP and distinguishes it from other blistering conditions.
Blood tests can also detect the circulating antibodies that target the skin-anchoring proteins, which helps confirm the diagnosis and can be useful for monitoring disease activity over time.
What This Means if a Relative Has BP
If a parent or sibling has been diagnosed with bullous pemphigoid, your risk is not meaningfully elevated in the way it would be for a clearly hereditary condition like sickle cell disease or cystic fibrosis. No consistent inheritance pattern has been documented for BP, and childhood cases are rare. There is no evidence of the condition being transmitted from mother to child during pregnancy through antibody transfer, which further supports its classification as an acquired disease rather than a familial one.
You may share some of the same HLA gene variants that create a slightly elevated baseline susceptibility, but that susceptibility is common in the general population and rarely leads to disease on its own. The overwhelming majority of BP cases occur sporadically in elderly individuals with no family history of the condition.