"Hailey-Hailey disease is an autosomal dominant disorder caused by a genetic defect in a calcium ATPase (ATP2C1) leading to a defect in keratinocyte adhesion. The characteristic of this disease is the involvement of intertriginous areas of the skin, which are the moist sites including the axillary vault and the inguinal crease. The composition of microbial communities is primarily dependent on the physiology of the skin site and the moist sites have distinct compositions of skin microorganisms. In addition, treatment with doxycycline is often helpful in the management of Hailey-Hailey disease. These findings suggest a role of the skin microbiome in the pathogenesis of Hailey-Hailey disease.

The purpose of this study is to characterize the skin microbiome in patients with Hailey-Hailey disease by the 16S method, to better understand the pathogenesis of the disease and to discover new therapeutic targets in the future.

Investigators will look at patients with Hailey-Hailey disease, and healthy controls.

Investigators will look at skin microbiome (Bacterial diversity and the relative abundance of major bacterial taxa) Investigators will assess this in patients with Hailey-Hailey disease before and after doxycycline and compare them to healthy controls.

Inclusion Criteria:

1. Hailey-Hailey disease 1-1. Inclusion Criteria

1. Clinically diagnosed with Hailey-Hailey as confirmed by histopathology and/or genetic analysis.
2. >19 years old
3. Patients who currently have lesions on the axilla and groin
4. Patietns who signed the consent form and Informed Consent in Human Material Research

2. Normal control 2-1. Inclusion Criteria

1. >19 years old
2. Persions who signed the consent form and Informed Consent in Human Material Research

Exclusion Criteria:

1-2. Exclusion Criteria

1. Patients who have used systemic steroids or antibiotics within the last 1 month
2. Patients who have used local steroids or antibiotics within the last 2 weeks
3. Patients who have been diagnosed with skin diseases(such as atopic dermatitis) other than Hailey-Hailey disease
4. Patients who are unable to swab or who may have affect a medical condition
5. Patients who have difficulty making clear decisions due to lack of decision-making ability
6. In addition to the above, a person who is considered inappropriate to participate in this study, such as collecting test information, based on the medical judgment of the Principal investigator or Subinvestigator.

2-2. Exclusion Criteria

1. Persions who have skin diseases(such as atopic dermatitis) or diseases affecting the skin microbes
2. Persions who have used systemic steroids or antibiotics within the last 1 month
3. Patients who have used local steroids or antibiotics within the last 2 weeks
4. In addition to the above, a person who is considered inappropriate to participate in this study, such as collecting test information, based on the medical judgment of the Principal investigator or Subinvestigator.

Patients with Hailey Hailey, diagnosis confirmed by histopathology or genetics at Gangnam Severance Hospital, Dermatology Department