What are the other Names for this Condition? (Also known as/Synonyms)

• Dark Dot Disease
• Kitamura Reticulate Acropigmentation
• Reticular Pigment Anomaly of Flexures

What is Dowling-Degos Disease? (Definition/Background Information)

• Dowling-Degos Disease (DDD) is a rare genetic condition of the skin that affects pigmentation. It results in increased pigmentation in the armpits and groin, blackhead spots on the neck, and pitted acne-liked scars on the chin
• Dowling-Degos Disease is caused by genetic mutation(s); at least 2 genes, namely KRT5 and POFUT1, are known to be involved. Due to this, a family history of the disorder is considered to be a key risk factor
• Even though Dowling-Degos Disease is a congenital disorder, the manifestation of signs and symptoms mostly occur during early adulthood. The condition then progresses throughout one’s life. A female prevalence is generally observed
• Blood tests for specific gene mutations may form the basis of diagnosing Dowling-Degos Disease. The treatment is symptomatic and involves skin therapy using topical applications and laser therapy, if necessary
• The prognosis is typically good for most individuals, since Dowling-Degos Disease is not a life-threatening condition. However, in some individuals, the skin symptoms may cause severe cosmetic issues leading to emotional distress and depression

Who gets Dowling-Degos Disease? (Age and Sex Distribution)

• Characteristics of Dowling-Degos Disease develop most commonly during the 20s and 30s. On an average, skin pigmentation is observed to develop before the age of 24
• The disorder affects both men and women; however, studies have shown a female predominance
• All races and ethnic groups can be affected

What are the Risk Factors for Dowling-Degos Disease? (Predisposing Factors)

• A family history of Dowling-Degos Disease is an important risk factor, since it is a genetic condition
• It is important to note that even though an individual may not have a family history of the condition, they may still develop the condition sporadically

It is important to note that having a risk factor does not mean that one will get the condition, A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Dowling-Degos Disease? (Etiology)

Dowling-Degos Disease is most commonly inherited from a single parent (in an autosomal dominant manner); however, the condition may also develop sporadically.

• Mutations in the genes KRT5 and POFUT1 have been linked to Dowling-Degos Disease
• Mutations in the KRT5 gene affect keratin 5 molecules
  • The mutation causes the molecules to become shorter than normal, making them essentially inactive
  • The keratin 5 molecule is involved in the transfer of melanin pigment from melanocytes to keratinocytes
  • This results in the patterns of pigmentation that are associated with Dowling-Degos Syndrome
• While the KRT5 and POFUT1 genes are known to cause the syndrome, there is a likelihood that there are other mutations that cause variations of this condition

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Dowling-Degos Disease?

The signs and symptoms of Dowling-Degos Disease vary among those affected due to the specific genetic mutation present/involved. Some have mild signs and symptoms, while others may have severe presentations. The symptoms are known to typically present themselves during early adulthood. Many of the symptoms are related to skin abnormalities.

The signs and symptoms of Dowling-Degos Disease may include:

• Increased skin pigmentation in areas such as armpits, groin, between and under the breasts, the upper arms and upper inner thighs, and behind the neck and knees
• The patterns of pigmentation may include:
  • Lacy (reticulated) patterns
  • Small black dots (dark spots)
  • Flat spots (macules)
  • Slightly raised small spots (papules)
  • Varying shades of brown or black pigmentation on lighter patches of skin
• Pigmentation might worsen during pregnancy or with sun exposure
• The presence of blackhead-like spots commonly found on the neck (comedones)
• And, the presence of pitted acne-liked scars found most often on the chin

How is Dowling-Degos Disease Diagnosed?

Dowling-Degos Disease is diagnosed in the following manner:

• Complete medical history and a thorough physical examination
• Assessment of signs and symptoms
• Blood tests for specific genetic mutations that cause DDD. The specific mutations include:
  • Mutations in the KRT5 gene
  • Mutations in the POFUT1 gene
• Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis.

In most cases, healthcare providers can suspect if an individual has Dowling-Degos Disease through the presenting signs and symptoms. However, genetic testing and/or skin biopsy are the only two methods of diagnosing Dowling-Degos Disease. 

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis. 

What are the possible Complications of Dowling-Degos Disease?

The possible complications of Dowling-Degos Disease include conditions that develop because of DDD. Some of these conditions include:

• Hidradenitis suppurative: It is a chronic skin condition that results in lumps on the skin appearing in places such as the armpits and/or groin
• Squamous cell carcinomas and keratoacanthomas - both occur as a result of an uncontrolled growth of the squamous cells
• Seborrheic keratosis: A non-cancerous condition that manifests as black, brown, or tan growths on the skin
• Pilar cysts: Cysts that occur along the outer hair root
• Nail dystrophy
• Absence of vellus hair (short, thin, light-colored hair that develops all over the body)

Severe emotional stress due to cosmetic issues and prolonged discomfort affecting one’s ability to study and work are also complications. 

How is Dowling-Degos Disease Treated?

Presently, there is no cure for Dowling-Degos Disease. Most treatment plans are established based on the specific set of symptoms noted in the individual.

Treatments to manage skin symptoms include the use of the following measures:

• Topical retinoic acids
• Topical steroids to aid in itch reduction
• Hydroquinone; a topical cream to lighten dark patches of skin
• Tretinoin; a topical cream that is used to treat acne and other skin conditions
• Systemic retinoids
• Temporary therapeutic benefits have been noted using topical adapalene. Topical adapalene is used in controlling itch and hyperpigmentation

Various lasers have also been used to clear up rashes on the chest through a process of continuous treatment. These include the CO2 laser system and the Erbium-YAG laser system.

How can Dowling-Degos Disease be Prevented?

Currently, there are no specific methods or guidelines to prevent Dowling-Degos Disease, since it is a genetic condition.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as DDD

Regular medical screening at periodic intervals with tests, scans, and physical examinations are mandatory.

What is the Prognosis of Dowling-Degos Disease? (Outcomes/Resolutions)

• The prognosis of Dowling-Degos Disease is generally good, as it is not a life-threatening condition
• However, DDD is a slowly progressive condition that is present throughout one’s life. In some individuals, it can cause severe depression
• The prognosis may be adversely affected due to associated conditions, such as hidradenitis suppurativa, squamous cell carcinomas, keratoacanthomas, and seborrheic keratosis

Additional and Relevant Useful Information for Dowling-Degos Disease:

It is important to differentiate between Dowling-Degos Disease and acanthosis nigricans. Acanthosis nigricans is a skin condition that presents similar symptoms to DDD; however, it is associated with other conditions such as obesity, diabetes, and malignancy.