Pathology
DSG1 is an autoantigen in pemphigus foliaceus
mutations of DSG1 cause type I striate keratosis palmoplantaris (PPKS type1) (MIM.148700)
toxic DSG1 inactivation in staphylococcal infections
Desmoglein-1 (DSG1) can be inactivated by germline mutations, autoantibody, or bacterial toxins.
Pemphigus foliaceum is an auto-immune blistering disease due to an inactivation of desmoglein-1 by an autoantibody. The relevant antibody in pemphigus foliaceus reacts with desmoglein-1, which is expressed in the uppermost epidermal layers, thus correlating with the characteristic subcorneal plane of blister formation in this variant.
DSG1 can also been inactivated by the exfoliative toxins produced by S. aureus, that are serine proteases that cleave the protein. This can cause the superficial epidermis to split away from the deeper skin, making the patient vulnerable to secondary infections.
Exfoliation can occur at the site of staphylococcal skin infection (bullous impetigo) or can be widespread, when secreted toxin from a localized infection causes disseminated loss of the superficial epidermis (staphylococcal scalded-skin syndrome or SSS).
Staphylococcal scalded skin syndrome (SSSS), also called Ritter disease, is caused by the exfoliative A and B toxins. It is an exfoliative dermatitis that most frequently occurs in children with staphylococcal infections of the nasopharynx or skin.
In staphylococcal scalded skin syndrome, there is a sunburnlike rash that spreads over the entire body and forms fragile bullae that lead to partial or total skin loss.
References
Payne AS, Hanakawa Y, Amagai M, Stanley JR. Desmosomes and disease: pemphigus and bullous impetigo. Curr Opin Cell Biol. 2004 Oct;16(5):536-43. PMID: 15363804
Whittock NV, Bower C. Targetting of desmoglein-1 in inherited and acquired skin diseases. Clin Exp Dermatol. 2003 Jul;28(4):410-5. PMID: 12823304