Pachyonychia Congenita (PC) Fact Sheet

Pachyonychia Congenita (PC)

Pachyonychia Congenita is a rare hereditary disorder that can affect the nails, skin, mouth, larynx, hair, and eyes. Currently, two distinct types of PC are recognized: PC-1, or Jadassohn-Lewandowsky type, and PC-2, or Jackson-Lawler type.

Pachyonychia Congenita is a genetically inherited disorder that follows an autosomal dominant pattern. Autosomal means that the genetic defect is carried on one of the 22 human chromosomes that do not determine sex. Dominant means that the gene with the mutation dominates over normal skin and produces.  A person with one dominant gene for PC and one gene for normal skin will have PC. Research data suggest that the mutations in keratins K6a and K16 are associated with PC-1 and mutations in keratins K6b and K17 are associated with PC-2. Keratins are proteins that are important to the normal function of hair, nails and skin.

 
The clinical features associated with Pachyonychia Congenita include:
 
PC- 1 Jadassohn-Lewandowsky type:
  • Thickened fingernails and toenails.
  • Plantar keratoderma - blisters and thick calluses on the soles of the feet.
  • Palmar keratoderma – blisters and thick calluses on the palms of the hands.
  • Oral leukokeratosis – thick white growths on the tongue and the insides of the cheeks.
  • Follicular keratoses – bumps that form around the hair follicles.
  • Possible involvement of the larynx – hoarseness or thickening of the voice box.
  • Hyperhydrosis (excessive sweating) and non-epidermal cysts.
PC-2 Jackson-Lawler type:
  • Thickened fingernails and toenails.
  • Plantar keratoderma – blisters and thick calluses on the soles of the feet.
  • Palmar keratoderma – blisters and thick calluses on the palms of the hands.
  • Oral leukokeratosis – thick white growths on the tongue and the insides of the cheeks.
  • Possible involvement of the larynx – hoarseness or thickening of the voice box.
  • Blistering of the palms and soles.
  • Hyperhydrosis – excessive sweating of the feet or hands.
  • Natal or prenatal teeth.
  • Cysts – including steatocystoma (epithelial/skin) type.
 

There may be additional forms of PC that are presently not well defined. No specific gene mutation has yet been identified for several syndromes that may be related to PC, including palmoplantar keratoderma (PPK), epidermolytic palmoplantar keratoderma (EPPK), and Tylosis or Unna-Thost syndrome.

Not every affected individual exhibits every clinical feature. Each person may display a unique set of signs and symptoms even within families. PC may be difficult to diagnose because the clinical features and their severity vary and they frequently overlap between types. Because of the difficulty in diagnosing this disorder, Pachyonychia Congenita types are currently defined and determined by a combination of physical findings and genetic mutation testing.

Treatment of PC is primarily symptomatic. Emollients (moisturizers) and keratolytics (products containing alpha-hydroxy acids) can be used for the hyperkeratoses. Routine grinding of the nail plates can minimize their interference with function. Severe cases can be treated systemically with oral synthetic retinoids (Accutane, Soriatane). Retinoids are only used in severe cases due to their known bone toxicity and other complications.

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Adapted from eMedicine.com, Keratosis Palmaris et Plantaris,Copyright 2002, eMedicine.com, Inc., and Pachyonychia Project.


PC Project
2386 East Heritage Way, Suite B
Salt Lake City, UT 84109
877.628.7300
www.pachyonychia.org


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