Dowling-Degos Disease 1

Alternative Names

  • DDD1
  • DDD
  • Reticular Pigmented Anomaly of Flexures
  • Dowling-Degos-Kitamura Disease
  • Kitamura Reticulate Acropigmentation
  • Reticulate Acropigmentation of Kitamura
  • RAK
  • Dark Dot Disease
  • Galli-Galli Disease
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WHO-ICD-10 version:2010

Diseases of the skin and subcutaneous tissue

Other disorders of the skin and subcutaneous tissue

OMIM Number

179850

Mode of Inheritance

Autosomal dominant

Gene Map Locus

12q13.13

Description

Dowling-Degos Disease, also known as reticulate acropigmentation of Kitamura or reticular pigmented anomaly of flexures, is a rare benign genodermatosis. Differentiation from acanthosis nigricans is important because of its favorable prognosis. Onset is most often in the 30- to 40-year age range. The disease is slowly progressive, but not life threatening. The anomaly initially affects the axillae and groins. Flexural pigmented reticulate macules and sometimes comedo-like papules occur on the back and/or the neck. Some patients have pitted perioral scars. Pruritus of affected flexural areas may be the only symptom. In both male and female patients, pigmented reticulate macules may also be evident on the genitalia. Later in life the intergluteal and inframammary folds, neck, trunk and arms may be involved.

Heterozygous mutations in the keratin-5 (KRT5) gene have been reported as the genetic cause of Dowling-Degos Disease.

Molecular Genetics

In 2006, it was proposed that loss-of-function mutations in the keratin-5 (KRT5) gene can lead to Dowling-Degos Disease. The 5-prime region of the KRT5 gene contains a TATA box and a potential CAAT box. The 3-prime region contains a single polyadenylation signal. The gene is expected to produce a 590-amino acid protein, K5, containing a central alpha-helical core region of about 310 amino acids with a 7-amino acid repeat found in coiled-coil structures. The N and C termini are serine rich and contain gly-gly-gly-x motifs. K5 appears to have two codominant alleles, a and b.

Epidemiology in the Arab World

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Other Reports

United Arab Emirates

Lestringant et al. (1997) examined 5 unrelated patients, 3 females and 2 males (age range 22-35 years), who presented with clinical and histological features of the Dowling-Degos Disease-Reticulate Acropigmentation of Kitamura spectrum. The patients presented with hypo- or depigmented macules and papules. Histopathology of the lesions revealed features that were identical to Dowling-Degos Disease-Reticulate Acropigmentation of Kitamura; there were, however, diminution or absence of pigmentation. Family histories for pigmented lesions and leukoderma were positive in all patients and consistent with autosomal dominant modes of inheritance. The observations of Lestrignant et al. (1997) lead them to hypothesize that achromic macules and papules may be a feature of the Dowling-Degos Disease-Reticulate Acropigmentation of Kitamura spectrum.

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