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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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Your Question

How many types of pachyonychia congenita are there? How are they caused? Is the condition more likely to occur in certain groups of people? How many individuals have this condition and what is the mortality rate?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

Are there different types of pachyonychia congenita?

Two major types of this condition have been described: pachyonychia congenita, type 1 (PC-1) and type 2 (PC-2). These types are distinguished by their genetic cause and features. Both types have the features mentioned above; however PC-2 has several additional features including widespread cysts during puberty; twisted, kinked, brittle, or coarse hair; and teeth that are present before birth or in early infancy.[1]

Variants of pachyonychia congenita have also been described and include: focal non-epidermolytic palmoplantar keratoderma (FNEPPK), with keratoderma occurring on the palms and soles but usually without nail abnormalities; steatocystoma multiplex (SM) with widespread cysts but with little or no nail involvement or palmoplantar keratoderma; and late-onset pachyonychia congenita (called PC tarda), which resembles either PC-1 or PC-2 and occurs from late childhood to middle age.[2]
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

Does pachyonychia congenita occur more often in certain people?

Pachyonychia congenita affects both sexes equally. Although the exact frequency of this condition is unknown, it appears to be rare. Approximately 450 cases of pachyonychia congenita have been described in the medical literature.[3] The Pachyonychia Congenita Project coordinates the International PC Research Registry to gather information on people diagnosed with this condition and support research.
Last updated: 5/15/2012

Do people with pachyonychia congenita have a shortened lifespan?

Pachyonychia congenita is not associated with a reduced lifespan.[3]
Last updated: 5/4/2011