Dowling-Degos disease (DDD) is an autosomal dominant genodermatosis characterized by reticular pigmentation, usually in a flexural distribution. However, generalized DDD can also occur, with numerous hypopigmented or erythematous macules and papules on the neck, chest, and abdomen. The histopathology of DDD shows characteristic thin branch-like patterns of epidermal downgrowth (summary by Li et al., 2013). Review of Reticulate Pigment Disorders Muller et al. (2012) reviewed the spectrum of reticulate pigment disorders of the skin, tabulating all reported cases of patients with Dowling-Degos disease, reticulate acropigmentation of Kitamura (RAK; 615537), reticulate acropigmentation of Dohi (RAD; 127400), Galli-Galli disease (GGD), and Haber syndrome (HS). Of 82 cases, 26 (31.7%) were clinically diagnosed as DDD, 13 (15.9%) as RAD, 11 (13.4%) as GGD, 8 (9.8%) as RAK, and 8 (9.8%) as HS; in addition, 16 (19.5%) of the cases showed overlap between DDD and RAK. Muller et al. (2012) also published photographs of an affected individual exhibiting an overlap of clinical features of DDD, GGD, RAD, and RAK. The authors noted that in reticulate disorders of the skin, the main disease entity is DDD, with a subset of cases exhibiting acantholysis (GGD), facial erythema (HS), or an acral distribution (RAD; RAK). Muller et al. (2012) concluded that all reticulate pigment diseases of the skin are varying manifestations of a single entity. Genetic Heterogeneity of Reticulate Pigment Disorders Dowling-Degos disease-2 (DDD2; 615327) is caused by mutation in the POFUT1 gene (607491) on chromosome 20q11. Dowling-Degos disease-3 (DDD3; 615674) has been mapped to chromosome 17p33.3. Dowling-Degos disease-4 (DDD4; 615696) is caused by mutation in the POGLUT1 gene (615618) on chromosome 3q13. Dyschromatosis symmetrica hereditaria (DSH; 127400), also known as reticulate acropigmentation of Dohi (RAD), is caused by mutation in the ADAR gene (146920) on chromosome 1q21. Reticulate acropigmentation of Kitamura (RAK; 615537) is caused by mutation in the ADAM10 gene (602192) on chromosome 15q21.