Association of ABO blood groups and vitiligo

Genetics of Vitiligo

Vitiligo reflects simultaneous contributions of multiple genetic risk factors and environmental triggers. Genomewide association studies have discovered approximately 50 genetic loci contributing to vitiligo risk. At many vitiligo susceptibility loci, the relevant genes and DNA sequence variants are identified. Many encode proteins involved in immune regulation, several play roles in cellular apoptosis, and others regulate functions of melanocytes. Although many of the specific biologic mechanisms need elucidation, it is clear that vitiligo is an autoimmune disease involving a complex relationship between immune system programming and function, aspects of the melanocyte autoimmune target, and dysregulation of the immune response.

Modern vitiligo genetics sheds new light on an ancient disease

Vitiligo is a complex disorder in which autoimmune destruction of melanocytes results in white patches of skin and overlying hair. Over the past several years, extensive genetic studies have outlined a biological framework of vitiligo pathobiology that underscores its relationship to other autoimmune diseases. This biological framework offers insight into both vitiligo pathogenesis and perhaps avenues towards more effective approaches to treatment and even disease prevention.

Six decades of vitiligo genetics: genome-wide studies provide insights into autoimmune pathogenesis

Generalized vitiligo (GV) is a complex disease in which patchy depigmentation results from autoimmune loss of melanocytes from affected regions. Genetic analyses of GV span six decades, with the goal of understanding biological mechanisms and elucidating pathways that underlie the disease. The earliest studies attempted to describe the mode of inheritance and genetic epidemiology. Early genetic association studies of biological candidate genes resulted in some successes, principally HLA and PTPN22, but in hindsight many such reports now seem to be false-positives. Later, genome-wide linkage studies of multiplex GV families identified NLRP1 and XBP1, which appear to be valid GV susceptibility genes that control key aspects of immune regulation. Recently, the application of genome-wide association studies to analysis of GV has produced a rich yield of validated GV susceptibility genes that encode components of biological pathways reaching from immune cells to the melanocyte. These genes and pathways provide insights into underlying pathogenetic mechanisms and possible triggers of GV, establish relationships to other autoimmune diseases, and may provide clues to potential new approaches to GV treatment and perhaps even prevention. These results thus validate the hopes and efforts of the early investigators who first attempted to comprehend the genetic basis of vitiligo.

Genetic association in vitiligo: ABO, MNSs, Rhesus, Kell and Duffy blood groups

One hundred and seventy Sudanese patients suffering from vitiligo were investigated for the distribution of A1A2BO, MNSs, Rhesus (genotypes), Kell and Duffy blood groups. The same genetic markers were investigated in Sudanese controls, consisting of two series: a published population series and a random sample of healthy blood donors. The relative frequencies of these blood groups were examined between the vitiligo patients and either or both of the control series. There was no significant association of ABO, Ss, Rhesus, Kell and Duffy blood groups in vitiligo. However, a significant association was observed with the MN system with an excess of homozygotes and of the M gene in vitiligo.

Associations between atopic diseases and the polymorphic systems ABO, Kidd, Inv and red cell acid phosphatase

In 239 German patients with atopic conditions (atopic dermatitis, hay fever, allergic rhinitis, bronchial asthma, and acute urticaria) the phenotype and gene distribution of 15 genetic blood polymorphisms (ABO, MNSs, rhesus, P, Kell, Duffy, Kidd, Hp, Gc, Gm, Inv, aP, PGM1, EsD, and 6-PGD) were analyzed and compared with those in 151 selected controls (individuals clinically free of allergic conditions and without allergy in the family history). The incidence of blood group antigens A and B was somewhat higher in patients than in controls. These observations are in accordance with the results of previous studies in other populations. In addition, our observations favor the hypothesis that there are also associations between the phenotypes Jk (a-b+), Inv(1) and red cell acid phosphatase aP A and aP AP on the one hand and atopic disposition on the other. The possible reasons for these associations are discussed.