Vitiligo is a chronic stigmatizing disease, already known for millennia, which mainly affects melanocytes from epidermis basal layer, leading to the development of hypochromic and achromic patches. Its estimated prevalence is 0.5% worldwide. The involvement of genetic factors controlling susceptibility to vitiligo has been studied over the last decades, and results of previous studies present vitiligo as a complex, multifactorial and polygenic disease. In this context, a few genes, including DDR1, XBP1 and NLRP1 have been consistently and functionally associated with the disease. Notwithstanding, environmental factors that precipitate or maintain the disease are yet to be described. The pathogenesis of vitiligo has not been totally clarified until now and many theories have been proposed. Of these, the autoimmune hypothesis is now the most cited and studied among experts. Dysfunction in metabolic pathways, which could lead to production of toxic metabolites causing damage to melanocytes, has also been investigated. Melanocytes adhesion deficit in patients with vitiligo is mainly speculated by the appearance of Köebner phenomenon, recently, new genes and proteins involved in this deficit have been found.

Vitiligo is a chronic disease characterized by macules devoid of melanin and identifiable melanocytes. Adhesion of melanocytes to the basement membrane by integrin CCN3 is mediated through collagen IV receptor DDR1. We hypothesize that genetic variants of the DDR1 gene are associated with the occurrence of vitiligo. To test this hypothesis, we genotyped 10 DDR1 tag single-nucleotide polymorphisms (SNPs) in 212 trios composed of an affected child and both parents. Associated markers were then genotyped in 134 independent, unrelated individuals with vitiligo and 134 unrelated controls. Allele T of tag SNP rs4618569 was associated with an increased risk for vitiligo in the family trios (P=0.002, odds ratio (OR)=5.27; 95% confidence interval (CI)=1.59-17.40), whereas allele C of tag SNP rs2267641 was associated with an increased risk for vitiligo in both family-based and case-control populations (P=0.01, OR=3.47; 95% CI=1.22-9.17; P=0.04, OR=6.00; 95% CI=1.73-52.33, respectively). The best evidence for association in the trios was obtained for a haplotype composed of risk alleles of markers rs4618569 and rs2267641 (P=0.0006). There was an age-dependent enrichment of rs4618569 T allele and rs2267641 C allele in early-onset affected individuals. In conclusion, we propose DDR1 as a susceptibility gene for vitiligo, possibly implicating a defective cell adhesion in vitiligo pathogenesis.

Vitiligo is a depigmenting disorder characterized by loss of functional melanocytes from the epidermis. Experimental data suggest that defective melanocyte adhesion may underlie the pathogenesis of the disease. In particular, association between vitiligo and genetic variants of the DDR1 gene involved in melanocyte adhesion has been recently published. A subsequent, independent study revealed lower expression of DDR1 in vitiligo lesions. Here, we expand this investigation by testing for association between vitiligo and polymorphisms of CDH1, IL1Band NOV (formerly CCN3), genes belonging to the DDR1 adhesion pathway, in two population samples of distinct design. Our results reveal that alleles of marker rs10431924 of the CDH1 gene are associated with vitiligo, especially in the presence of autoimmune comorbidities.

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See supporting information (Data S3).