Programmed cell death 1 gene (PDCD1) polymorphism and pemphigus foliaceus (fogo selvagem) disease susceptibility

Pemphigus foliaceus, also known as fogo selvagem, is an autoimmune disease of the epidermis characterized by superficial blisters and antibodies against desmoglein 1. It is a multifactorial disease and genetic susceptibility is oligogenic or polygenic. Considering the crucial function of the programmed cell death 1 molecule (PD-1) in the immune response, the aim of this study was to verify if variants of the PDCD1 gene influence susceptibility and resistance to pemphigus foliaceus, in a case control disease association study. We analyzed patients (n = 154) and unaffected control individuals (n = 325) of the Brazilian population, in respect to the PD1.3(G,A) PD1.5(C,T) and PD1.6(A,G) single nucleotide polymorphisms (SNPs) and also investigated, for the first time, the exon 5 PDCD1 microsatellite (CTG)n. The patient and control samples were divided into strata, according to the predominant ancestry of the individuals (African or European). The PD1.5 genotype distribution in the patients sample was almost indistinguishable from that in the control sample, in both population strata. A possible negative association between pemphigus foliaceus and allele PD1.3A was observed in the total African and European ancestry population sample (odds ratio (OR) = 0.55, p = 0.066) and should be investigated in forthcoming studies. The PD1.6A allele was over-represented among the patients of predominantly European ancestry due to an increase of both the G/A and the A/A genotypes (OR = 2.12 and 1.74, respectively; p = 0.035). We conclude that polymorphisms of the PDCD1 gene may influence susceptibility to pemphigus foliaceus, at least in Brazilians of predominantly European ancestry.