Single nucleotide polymorphism-based genome-wide linkage analysis in Japanese atopic dermatitis families

We used a high-density, single nucleotide polymorphism genotyping assay, the Illumina BeadArray Linkage Mapping Panel (version 4) comprising 5,861 single nucleotide polymorphisms, to perform a genome-wide linkage analysis of 77 Japanese families with 111 affected sib-pairs with atopic dermatitis.We found suggestive evidence for linkage with 15q21 (LOD = 2.01, NPL = 2.87, P = .0012) and weak linkage to 1q24 (LOD = 1.26, NPL = 2.44, P = .008).We report the first genome-wide linkage study of atopic dermatitis in an Asian population, and novel loci on chromosomes 15q21 and 1q24 linked to atopic dermatitis. Identification of novel causative genes for atopic dermatitis will advance our understanding of the pathogenesis of atopic dermatitis.Atopic dermatitis (ATOD) is a hereditary, pruritic, inflammatory, chronic skin disease that occurs most commonly in early childhood but can persist or start in adulthood. The prevalence of ATOD has been studied in a wide variety of populations [1], and its frequency ranged from 0.73% to 23% of the study populations. The 12-month prevalence value of symptoms of atopic eczema in Japanese children 6 to 7 years of age was 16.9%, the second highest after Sweden [2]. Living in lower, more tropical latitudes, rural areas, and less industrialized regions correlates with a lower prevalence of ATOD[1]. The etiology of ATOD is not fully understood, but atopy, which is characterized by increased levels of immunoglobulin E (IgE) against common environmental allergens, is considered one of the strongest predisposing factors for ATOD.ATOD is associated with cutaneous hyperresponsiveness to environmental triggers that are innocuous to healthy individuals [3]. In the acute lesions of ATOD, marked perivascular infiltration of inflammatory cells consisting predominantly of lymphocytes and occasional monocyte-macrophages is frequently observed. In chronic lichenified lesions, there are increased numbers of Langerhans' cells and mast cells in the epidermis,