Disseminated papular variant of Dowling-Degos disease: Histopathological features in POGLUT1 mutation.

Dowling-Degos disease is a rare benign genodermatosis. It is characterized by lentiginous hyperpigmentation and reddish-brown papules and plaques. The flexor sides and intertrigines are often affected, but the clinical appearance may vary. Mutations in different genes are responsible for the clinical manifestation. While mutations in the keratin 5 (KRT5) gene favor a reticular distribution pattern, mutations in the POGLUT1 gene lead to a disseminated, papular clinical picture. Acantholytic variants of Dowling-Degos disease have historically been referred to as Galli-Galli disease, but our case study shows that the histopathological changes can vary even within a single patient. To date, no standardized therapy concept exists. The main focus is on keratolytic measures, with varying response. New therapeutic approaches using laser technology appear to be a promising treatment option.

Dowling-Degos disease: a review.

Dowling-Degos disease is a rare autosomal dominant genodermatosis. It is characterized by acquired reticulate hyperpigmentation over the flexures, comedone-like follicular papules, and pitted perioral scars that usually develop during adulthood. Mutations in genes affecting melanosome transfer, and melanocyte and keratinocyte differentiation have been implicated in the pathogenesis of this disease. These genes include KRT5, POFUT1, POGLUT1 and, most recently, PSENEN. Dowling-Degos disease can be found in isolation or with other associated findings, most notably hidradenitis suppurativa. This condition belongs to a spectrum of conditions that all result in reticulate hyperpigmentation that at times are hard to distinguish from each other. The most closely linked entity is Galli-Galli, which is clinically indistinguishable from Dowling-Degos disease and can only be distinguished by the presence of acantholysis on microscopy. Unfortunately, Dowling-Degos disease is generally progressive and recalcitrant to treatment.

The deregulation of NOTCH pathway, inflammatory cytokines, and keratinization genes in two Dowling-Degos disease patients with hidradenitis suppurativa.

Dowling-Degos disease (DDD) is a rare autosomal-dominant genodermatosis and it has been associated with hidradenitis suppurativa (HS). Deregulation of NOTCH pathway has been linked to the development of HS in DDD context (DDD-HS). However, molecular alterations in DDD-HS, including altered gene expression of NOTCH and downstream effectors that are involved in the follicular differentiation and inflammatory response, are poorly defined. We report two cases of patients diagnosed with DDD-HS, one of those, under Adalimumab treatment. Our results have shown downregulation of NOTCH1/NCSTN pathway, distinct molecular profiles of inflammatory cytokines (IL23A and TNF), and a novel aberrant upregulation of genes involved in the cornified envelope (CE) formation (SPRR1B, SPRR2D, SPRR3, and IVL) in paired HS lesions of two DDD patients.

Scrotal Dowling-Degos disease caused by a novel frameshift variant in gamma-secretase subunit presenile enhancer gene.

We reported a Chinese pedigree with scrotal Dowling-Degos disease and evaluated the phenotypic and genotypic characteristics. In affected cases, pigmented macules were identified on the scrotum. The rashes increased, and the colour deepened progressively. No pain or pruritus were noticed, and no other skin folds were involved. Skin histopathology showed characteristic features of Dowling-Degos disease. A heterozygous PSENEN frameshift variant c.292delC（p.L98Wfs*47） was identified in affected cases. The variant was not found in dbSNP, 1000 Genomes project database and the ExAC Browser. The p.L98 and adjacent amino acids are highly conserved among species. Our cases expand the phenotypic and genotypic spectrum of PSENEN-related Dowling-Degos disease.

Quantifying Differences in Heritability among Psoriatic Arthritis (PsA), Cutaneous Psoriasis (PsC) and Psoriasis vulgaris (PsV).

Chronic plaque psoriasis and psoriatic arthritis are multifactorial inter-related diseases with strong genetic contributions. Better elucidation of the heritability of psoriatic disease subsets is important for identifying novel genes, risk stratification and potential clinical applications. In this study, we used two mixed-effect modelling methodologies to assess the additive contribution of common single nucleotide polymorphisms from genome-wide association studies to estimate the heritability of cutaneous psoriasis, psoriasis vulgaris and psoriatic arthritis. We found that cutaneous psoriasis and psoriatic arthritis both exhibit considerable heritability, with a greater contribution coming from cutaneous psoriasis.

Dyschromatosis symmetrica hereditaria and reticulate acropigmentation of Kitamura: An update.

Dyschromatosis symmetrica hereditaria (DSH) and reticulate acropigmentation of Kitamura (RAK) are rare, inherited pigmentary diseases. DSH shows a mixture of pigmented and depigmented macules on the extremities. RAK shows reticulated, slightly depressed pigmented macules on the extremities. The causative gene of DSH was clarified as ADAR1 by positional cloning including linkage analysis and haplotype analysis in 2003. Ten years later, the causative gene of RAK was identified as ADAM10 by whole-exome sequencing, in 2013. ADAR1 is an RNA-editing enzyme which catalyzes the deamination of adenosine to inosine (A-to-I) in double-stranded RNA substrates during post-transcription processing. Inosine acts as guanine during translation, resulting in codon alterations or alternative splice sites that lead to functional changes in proteins when they occur in coding regions. In 2012, it was clarified that ADAR1 mutations cause Aicardi-Goutières syndrome 6, which is a severe genetic inflammatory disease that affects the brain and the skin. A zinc metalloprotease, a disintegrin and metalloprotease domain-containing protein 10 (ADAM10), is involved in the ectodomain shedding of various membrane proteins and shows various functions in vivo. ADAM10 is known to be involved in the ectodomain shedding of Notch proteins as substrates in the skin. We speculate that the pathogenesis of RAK and Dowling-Degos disease (DDD, a pigmentary disease similar to RAK) is associated with the Notch signaling pathway. In addition, ADAM10 mutations proved to be associated with late-onset Alzheimer disease. This review comprehensively discusses the updated pathophysiology of those genetic pigmentary disorders.