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The kappa light chain constant region of immunoglobulins bears polymorphic markers involved in susceptibility to various autoimmune diseases. To determine whether it also contributes to the occurrence of pemphigus, a group of autoimmune blistering skin diseases owing to pathogenic autoantibodies, the genotypic frequencies of Km allotypes were evaluated in patients with pemphigus foliaceus or pemphigus vulgaris and ethnically-matched healthy controls in both Tunisia and France. No difference in the distribution of Km genotype or allele frequencies was observed between patients and controls in either countries. Therefore, Km allotypes do not appear to constitute a genetic factor contributing to pemphigus.

Two polymorphic markers were identified on the desmoglein 1 gene which encodes the autoantigen targeted by pathogenic antibodies in pemphigus foliaceus (PF), a cutaneous autoimmune blistering disease. The first marker, made of a variant haplotype of five mis-sense mutations located on the part of the gene encoding the fourth and fifth extracellular domains of the protein, is not associated with the disease. The second marker consists of a single silent T to C transition at position 809 and was found to be significantly more frequent (P = 0.015) in Caucasian PF patients (n = 36) than in controls (n = 98). Thus, pemphigus foliaceus constitutes another example of autoimmune disease in which the autoantigen polymorphism contributes to disease susceptibility.