Hailey-Hailey Disease
Hailey-Hailey disease, also known as benign chronic pemphigus, is a rare skin condition that usually appears in early adulthood. The disorder is characterized by red, raw, and blistered areas of skin that occur most often in skin folds, such as the groin, armpits, neck, and under the breasts. These inflamed areas can become crusty or scaly and may itch and burn. The skin problems tend to worsen with exposure to moisture (such as sweat), friction, and hot weather.
The severity of Hailey-Hailey disease varies from relatively mild episodes of skin irritation to widespread, persistent areas of raw and blistered skin that interfere with daily activities. Affected skin may become infected with bacteria or fungi, leading to pain and odor. Although the condition is described as "benign" (noncancerous), in rare cases the skin lesions may develop into a form of skin cancer called squamous cell carcinoma.
.Many affected individuals also have white lines running the length of their fingernails. These lines do not cause any problems, but they can be useful for diagnosing Hailey-Hailey disease.
Frequency
Hailey-Hailey disease is a rare condition; its prevalence is unknown.
Causes
Hailey-Hailey disease results from mutations in the ATP2C1 gene. This gene provides instructions for producing a protein called hSPCA1, which is found in many types of cells. The hSPCA1 protein helps cells store calcium until it is needed. Calcium has several critical functions in cells, including regulating cell growth and division (proliferation) and helping cells stick to one another (cell adhesion). The hSPCA1 protein appears to be particularly important for the normal function of cells called keratinocytes, which are found in the outer layer of the skin (the epidermis). In addition to proliferation and adhesion, calcium regulation in keratinocytes plays an important role in the barrier function of skin, which helps keep foreign invaders such as bacteria out of the body.
Mutations in the ATP2C1 gene reduce the amount of functional hSPCA1 protein in cells. This abnormality impairs cells' ability to store calcium normally. For unknown reasons, this abnormal calcium storage affects keratinocytes more than other types of cells. The abnormal regulation of calcium impairs many cell functions, including cell adhesion. As a result, keratinocytes do not stick tightly to one another, which causes the epidermis to become fragile and less resistant to minor trauma. Because the skin is easily damaged, it develops raw, blistered areas, particularly in skin folds where there is moisture and friction. In addition, abnormal calcium regulation disrupts the barrier function of the skin, making it more susceptible to infections. However, it is unclear how a reduction of hSPCA1 protein function affects the skin barrier, and how its impairment is involved in Hailey-Hailey disease.
Learn more about the gene associated with Hailey-Hailey disease
Inheritance Pattern
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.