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Genetic and Rare Diseases Information Center (GARD)

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Pachyonychia congenita


Other Names for this Disease
  • Congenital pachyonychia
  • Pachyonychia congenita syndrome
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Overview



What is pachyonychia congenita?

What causes pachyonychia congenita?

How is pachyonychia congenita inherited?

Is genetic testing available for pachyonychia congenita?

How is pachyonychia congenita diagnosed?

How might pachyonychia congenita be treated?


What is pachyonychia congenita?

Pachyonychia congenita (PC) is a very rare inherited condition that primarily affects the nails and skin. The fingernails and toenails are usually thickened and abnormally shaped. Affected individuals may also develop painful calluses and blisters on the soles of their feet and palms of their hands (palmoplantar keratoderma). Additional features include white patches on the tongue and inside of the mouth; bumps around the elbows, knees, and waistline; cysts in the armpits, groin, back, or scalp; and excessive sweating on the palms or soles of the feet. Features may vary among affected individuals.[1]

Two major types of this condition have been described: pachyonychia congenita type 1 (PC-1) and pachyonychia congenita type 2 (PC-2). PC is caused by a mutation in one of four genes. Mutations in the KRT6A and KRT16 gene cause PC-1; mutations in KRT6B and KRT17 result in PC-2.[1]
Last updated: 5/4/2011

What causes pachyonychia congenita?

This condition is caused by a mutation in one of four genes. Mutations in the KRT6A and KRT16 gene cause PC-1; mutations in KRT6B and KRT17 result in PC-2. These genes provide instructions for making a protein called keratin, which is found in the skin, hair, and nails. Mutations in any of these genes cause the features seen in pachyonychia congenita.[1]
Last updated: 5/10/2011

How is pachyonychia congenita inherited?

This condition is inherited in an autosomal dominant manner. In autosomal dominant conditions, a mutation in one of the two copies of a gene results in the development of the condition. The mutation can be inherited from a parent, or can happen by chance for the first time in an individual. About half of the time, an affected person inherits the mutation from one affected parent. Each child of an individual with pachyonychia congenita has a 50% chance of inheriting the mutation and the condition. Offspring who inherit the mutation will have pachyonychia congenita.[1]
Last updated: 5/4/2011

Is genetic testing available for pachyonychia congenita?

Yes, genetic testing is available for this condition. GeneTests lists the names of laboratories that are performing genetic testing for pachyonychia congenita. To view the contact information for the clinical laboratories conducting testing for pachyonychia congenita type 1, click here. For clinical laboratories conducting testing for pachyonychia congenita type 2, click here

Please note:  Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional. Below, we provide a list of online resources that can assist you in locating a genetics professional near you.
Last updated: 5/4/2011

How is pachyonychia congenita diagnosed?

A clinical diagnosis of this condition can usually be made based on the nail findings in association with painful palmoplantar keratoderma. Other clinical findings include blistering on the hands and feet; white patches on the tongue and inside of the mouth; bumps around the trunk and extremities; and cysts in the armpits, groin, back, or scalp. PC-2 might be suspected in individuals with additional findings such as natal or prenatal teeth, benign lesions on the body, and twisted hair.[2]

A diagnosis can also be made through genetic testing of the four keratin genes known to be associated with this condition.[2]
Last updated: 5/4/2011

How might pachyonychia congenita be treated?

There is no cure for this condition. Current treatments focus on symptom relief (such as soaking the feet or applying creams), hygienic grooming practices (such as trimming the nails and calluses), and treatment of secondary infections when indicated. To read more about treatment options, click here.[2]
Last updated: 5/4/2011

References
  1. Pachyonychia congenita. Genetics Home Reference. August 2008; http://ghr.nlm.nih.gov/condition/pachyonychia-congenita. Accessed 5/4/2011.
  2. Smith FJD, Kaspar RL, Schwartz ME, McLean WHI, Leachman SA. Pachyonychia Congenita. GeneReviews. June 2009; http://www.ncbi.nlm.nih.gov/books/NBK1280/. Accessed 5/4/2011.