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Keratosis Follicularis

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NORD is very grateful to Dr. Susan Burge, Associate Director of Clinical Studies and Consultant Dermatologist, Churchill Hospital, Oxford, United Kingdom, for assistance in the preparation of this report.

Synonyms of Keratosis Follicularis

Disorder Subdivisions

General Discussion

Keratosis follicularis, also known as Darier disease, is a rare, genetic skin disorder. Affected individuals develop skin lesions that consist of thickened, rough bumps (papules) or plaques that may also be greasy or have a brown or yellow crust. These hardened, scaly lesions are progressive and may gradually grow bigger or spread. The nails and mucous membranes are also affected in most cases. Individuals may have periods of time when signs improve (remission), but the lesions usually recur (relapse). The specific problems vary from one individual to another. Keratosis follicularis is inherited as an autosomal dominant trait.


The symptoms of keratosis follicularis usually become apparent during the teen-age years often around puberty. Symptoms may develop in younger or older individuals, but rarely develop after the third or fourth decade of life. The severity of the disorder and the specific symptoms that develop vary, even among individuals within the same family.

The initial lesions in keratosis follicularis are usually small, firm, greasy bumps (papules) that are often skin-colored, brown or yellow-brown in color. The lesions usually affect the areas of the body near sebaceous glands (sebaceous glands secrete oily grease) including the chest, back, forehead and scalp. Darier disease may also affect skin creases e.g. groin.

The skin lesions associated with keratosis follicularis generally develop a brown, greasy crust and become thickened (hyperkeratosis), scaly and darkened. The lesions will slowly grow bigger eventually coming together (coalescing) to form large discolored, warty plaques that may cover significant portions of the body. In extremely rare, severe cases, almost the entire body may be affected. The lesions may cause persistent itchiness (pruritus). Some patients have fragile skin that blisters or becomes raw (erosions) and painful.

The skin may develop bacterial, viral or fungal infections (secondary infections) that worsen (exacerbate) the condition. Infected skin lesions may give off a distinct, unpleasant (malodorous) smell. The herpes simplex virus may be prone to infecting the lesions and causes pain. Heat, exercise and sunlight may also worsen keratosis follicularis or cause a new outbreak of lesions.

Individuals with keratosis follicularis may have periods when few lesions are present (remission). However, the lesions tend to recur (relapse). Keratosis follicularis is usually worse in the summer and improves in the winter. Heat or sun often cause an outbreak.

Another common finding associated with keratosis follicularis is the development of multiple, small, yellow-brown, flattened wart-like (verrucous) bumps (papules) on backs of the hands or feet. These bumps may be the first sign of keratosis follicularis. Many affected individuals develop small horny bumps called punctate keratoses or depressions (pits) on the palms and soles.

Most individuals with keratosis follicularis have abnormalities affecting the nails including fragile nails with splits along the length of the nail or red or white streaks that run up and down the nail with V-shaped notching at the free edge

Sometimes the mucous membranes within the mouth develop small bumps (papules). The roof of the mouth (palate) is most often affected. The gums, larynx and esophagus may also be affected. Darier disease can also affect the salivary glands causing salivary gland obstruction. In some cases, Darier’s disease has developed on the mucous membranes of the anus and rectum.

Although in most people, Darier's disease is limited to the skin, additional symptoms have been reported in some cases including seizures, bipolar disorder, and learning disabilities.

Keratosis follicularis may -be restricted to a band of skin on one side of the body (segmental or linear keratosis follicularis)


Keratosis follicularis is a genetic disorder that occurs randomly as the result of a spontaneous genetic change (i.e., new mutation) or is inherited as an autosomal dominant trait.

Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.

Investigators have determined that keratosis follicularis occurs due to mutations of the ATP2A2 gene located on the long arm (q) of chromosome 12 (12q23-q24.1). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For example, "chromosome 12q23-q24.1" refers to bands 23-24.1 on the long arm of chromosome 12. The numbered bands specify the location of the thousands of genes that are present on each chromosome.

The ATP2A2 gene contains instructions for creating (encoding) a protein that acts as a calcium pump in the cell. This protein known as SERCA2, is responsible for carrying calcium ions from the semi-transparent fluid (cytoplasm) found in the interior of a cell into the extensive membrane network of a cell (endoplasmic reticulum) where proteins are processed. The exact process by which loss or improper function of the SERCA2 protein causes keratosis follicularis is unknown but SERCA2 is active (expressed) in keratinocytes, the main cell type of the outermost layer of the skin (epidermis). Calcium ions in the endoplasmic reticulum play an essential role in the formation of the proteins in the sticky junctions known as a desmosomes that hold the keratinocytes together. When the calcium pumps fail, the desomsomes do not hold cells together properly and the keratinocytes separate (acantholysis). Failure of keratinocytes to stick together also leads to abnormal maturation of the keratinocytes (abnormal keratinization) with the formation of the horny bumps. For this reason, keratosis follicularis is sometimes referred to as a disorder of abnormal keratinization or dyskeratosis.

The linear or segmental forms of keratosis follicularis are caused by genetic mosaicism. ie the Darier mutation is only present in some of the cells in one part of the skin but most of the skin is not affected. Mosaicism is caused by a mutation in a single cell after fertilization (postzygotic mutation) and is not inherited.

Affected Populations

Keratosis follicularis affects males and females in equal numbers. It is estimated to occur in 1 in 36,000 to 100,000 individuals in the general population. The disorder usually becomes apparent during the second decade in life, but has developed in individuals as young 4 and older than 70. Keratosis follicularis was first described in the medical literature in 1889.

Related Disorders

Symptoms of the following disorders can be similar to those of keratosis follicularis. Comparisons may be useful for a differential diagnosis.

Hailey-Hailey disease, also known as benign familial chronic pemphigus, is another rare genetic skin disorder. Hailey-Hailey disease is characterized by blistering, erosive skin lesions that most often form on the neck, chest, armpits and groin. The skin may itch or burn. Secondary infection is common. Most individuals develop symptoms in the third or fourth decade of life. The lesions may disappear on their own, but can recur. Heat, friction, sunlight and trauma may cause an outbreak or worsen existing symptoms. Hailey-Hailey disease is caused by mutations of the ATP2C1 gene, a gene that encodes another cacium pump, and Hailey-Hailey disease is also inherited as an autosomal dominant trait. The desomsomes do not function correctly in Hailey- Hailey disease. (For more information on this disorder, choose "Hailey-Hailey" as your search term in the Rare Disease Database.)

Acrokeratosis verruciformis of Hopf is a rare genetic skin disorder. Symptoms of the disorder include flat-topped or slightly convex, smooth, firm, elevated spots (papules) usually distributed symmetrically on the back of the hands, feet, wrists and/or ankles. Spots may be few or numerous; they may range in size from 1/16 to 1/4 inch. Spots are mostly flesh-colored, some are light brown. The palms of the hands and the soles of the feet may be hardened (hyperkeratotic). The nails may be opaque and brittle. Acrokeratosis verruciformis of Hopf may be allelic to keratosis follicularis, which means the two disorders are caused by different mutations of the same gene (ATP2A2).

Grover's disease, also known as transient acantholytic dermatosis, is an acquired skin disorder characterized by the sudden appearance of small, firm, raised itchy red bumps, most often on sun-damaged skin of the chest and back. The desmosomes fail to hold the keratinocytes together in Grover's disease as they do in Darier's disease. The bumps may disappear after six to 12 months or persist for years. Grover's disease is mainly seen in men older than forty or fifty. The cause is uncertain but heat, sweating and sun damage seem to play a part. (For more information on this disorder, choose "Grover's disease" as your search term in the Rare Disease Database.)

Standard Therapies

A diagnosis of keratosis follicularis is made based upon a thorough clinical evaluation, a detailed patient history, identification of characteristic findings and microscopic examination (biopsy) of affected skin tissue. A biopsy may reveal abnormal formation of keratin tissue (keratinization) and failure of cell-to-cell adhesion (acantholysis).

The treatment of keratosis follicularis is directed toward the specific symptoms that are apparent in each individual. For some individuals, sunscreen, loose clothing, moisturizing creams and avoiding excessive heat may reduce the severity of the disease.

Synthetic derivatives of vitamin A (retinoids) applied directly to the affected areas (topically) may help reduce scaly thickening of the skin (hyperkeratosis). Therapy that helps soften and shed hardened, abnormal skin (keratolytics) such as treatment with salicylic acid in propylene glycol gel may also help treat hyperkeratosis. Topical corticosteroids and substances that soothe and soften the skin (emollients) have also been used to alleviate inflammation in localized keratosis follicularis.

Retinoids taken by mouth (orally) have been effective in treating individuals with keratosis follicularis and are the drugs most often used to treat severe cases. Oral retinoids such as tretinoin and acitretin affect the entire body (systemic therapy). Oral retinoids can be associated with side effects. Women must not become pregnant when taking a retinoid because these drugs could damage the baby and pregnancy should be avoided for some time after stopping the drug (the exact time depends on which retinoid was prescribed). Retinoidsshould only be used under the supervision of a physician.

Antibiotics may be necessary to treat individuals with secondary bacterial infection. Antiviral agents such as acyclovir have been used to treat associated infection with the herpes simplex virus.

Genetic counseling is important for affected individuals and their families.

Investigational Therapies

Additional therapies have been used to treat affected individuals including erbium: YAG laser resurfacing, in which physicians use a laser to destroy the damage cells that make up the characteristic skin lesion of keratosis follicularis. This form of laser therapy has led to a remission in two affected individuals. More research is necessary to determine the long-term safety and effectiveness of the erbium: YAG laser for individuals with keratosis follicularis.

Photodynamic therapy, a procedure in which a drug known as a photosensitizer is used along with a special type light, has been used to treat some individuals with keratosis follicularis. During photodynamic therapy, the drug is administered to an affected individual and absorbed by the affected cells. A specific wavelength of light is used to active the drug which binds with oxygen creating a chemical that destroys the affected cell. More research is necessary to determine the long-term safety and effectiveness of photodynamic therapy for individuals with keratosis follicularis.

Controlled surgical scraping (dermabrasion) has also been used to treat some affected individuals.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

Keratosis Follicularis Resources

NORD Member Organizations:

(To become a member of NORD, an organization must meet established criteria and be approved by the NORD Board of Directors. If you're interested in becoming a member, please contact Susan Olivo, Membership Manager, at solivo@rarediseases.org.)

Other Organizations:


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Report last updated: 2012/02/01 00:00:00 GMT+0