HHD, Hailey-Hailey Disease or Chronic Benign Familial Pemphigus, is a genetic acantholytic (blistering) skin condition resulting from a mutation on one copy of chromosome 3 that encodes the protein ATP2C1. The mutation is found specifically at location 3.q22.1. Each copy of the gene is responsible for making this protein, therefore the lack of two good copies of the gene results in only 50% correct protein. This type of genetic disease is called a haploinsufficiency and results in a dominant inheritance pattern. The chances for each child of an affected parent to inherit the disorder is 50% (1:2).
ATP2C1 protein is responsible for calcium ion transport in a part of the skin cell called the Golgi Apparatus. The deficiency of protein in HHD makes the skin more fragile. Outbreaks are exacerbated by friction, sweat and secondary infections. Blisters seen during an outbreak often resemble those found in pemphigus vulgaris, although HHD is NOT an autoimmune disease, like pemphigus vulgaris, and there is no circulating autoantibody.
Because the disease is genetic, there is no cure. Treatment consists of oral antibiotics, anti-fungals and/or anti-virals to control secondary infection, astringents, cool compresses and dressings. Topical steroid creams help in most cases, although their long-term use is discouraged due to thinning of the already sensitive skin. Oral or intramuscular steroids, dapsone, botulinum toxin, laser resurfacing, dermabrasion or skin grafting may be tried in severe cases.
