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

• Congenital Pachyonychia
• Pachyonychia Congenita Syndrome
• PC (Pachyonychia Congenita)

What is Pachyonychia Congenita? (Definition/Background Information)

• Pachyonychia Congenita (PC) constitutes a rare group of genetic disorders that are primarily characterized by a triad of symptoms that include:
  • Thickened skin of the palms and soles
  • Thickened nails of the fingers and toes
  • Plantar pain (pain at the bottom of the feet, near the heel)
• Based on the involved gene, Pachyonychia Congenita is subdivided into five types, namely PC-K6a, PC-K6b, PC-K6c, PC-K16, and PC-K17. PC is inherited in an autosomal dominant manner, and a positive family history is an important predisposing factor
• The treatment of Pachyonychia Congenita involves the use of moisturizers, skin softeners, and systemic medications, including the use of assistive devices. The prognosis of the disorder is determined on a case-by-case basis and may vary based on its severity. In general, Pachyonychia Congenita is a lifelong disorder causing a reduced quality of life

Who gets Pachyonychia Congenita? (Age and Sex Distribution)

• Pachyonychia Congenita is a rare inherited disorder. Approximately, 1,000 cases have been reported in the scientific literature. Some reports inform that the condition may be underdiagnosed in many cases
• It is a congenital condition, although the manifestation of symptoms may begin at any age
• Both genders may be affected by this condition
• Worldwide, individuals of all raced and ethnic groups may be affected

What are the Risk Factors for Pachyonychia Congenita? (Predisposing Factors)

• A positive family history may be an important risk factor, since Pachyonychia Congenita is an inherited condition
• Currently, no other risk factors have been clearly identified for this disorder

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 Pachyonychia Congenita? (Etiology)

Pachyonychia Congenita is an autosomal dominant disorder that is typically inherited from one’s parents. The involvement (mutations) of one of the five keratin genes, namely KRT6A, KRT6B, KRT6C, KRT16, and KRT17 is observed in this disorder.

• Keratin is a protein found in nails, skin, and hair. When any one of the five genes is mutated, the respective keratin protein may not form properly or in sufficient quantities
• This leads to a weakening of the structure and flexibility of the tissue involved, leading to the characteristic signs and symptoms of the disorder

Autosomal dominant inheritance: 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 Pachyonychia Congenita?

The signs and symptoms of Pachyonychia Congenita may vary from one individual to another based on the specific subtype (gene involved). In many children, most of the signs and symptoms may be noted by age 10. These may be mild or severe. The common features noted include:

• Palmoplantar keratoderma - thickened skin of the palms and soles
• Thickened nails of the fingers and toes
• Pain in the plantar region (bottom of the feet, near the heel), which may be severe
• White patches in the mouth
• Ulcer sores at mouth corners
• Pain while swallowing or eating that may be severe in intensity
• Presence of sebaceous gland cysts (steatocystoma and pilosebaceous cysts)
• Swollen hair follicles (follicular hyperkeratosis)
• Fully developed teeth at birth (natal teeth)
• Hoarse cry in very young children

Additionally, the following may be noted:

• Skin lesions in the form of plaques, blisters, and cysts
• The lesions may be adversely affected by factors such as friction, increased sweating, and hot-humid weather
• Chapped lips
• Dry hair 
• Furrowed tongue
• Swollen gums
• Nail dystrophy and nail color abnormality
• Increased sweating, especially of the palms and soles
• Sparse hair on scalp and eyebrows
• Tooth decay

How is Pachyonychia Congenita Diagnosed?

Pachyonychia Congenita is diagnosed on the basis of the following information:

• Complete physical examination with evaluation of family medical history
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• 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
• Molecular genetic testing to check for or confirm specific causative gene mutation(s)
• Prenatal testing in pregnant women

A differential diagnosis may be necessary to eliminate other conditions that present similar signs and symptoms. This may include:

• Clouston syndrome
• Nail psoriasis
• Olmsted syndrome
• Onychomycosis
• Oral candidiasis
• Palmoplantar keratoderma striata
• Steatocystoma multiplex

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 Pachyonychia Congenita?

The complications of Pachyonychia Congenita may include:

• Severe emotional stress
• Secondary bacterial and fungal infections
• Hair loss
• Feeding problems
• Severe and constant pain due to plantar keratoderma - unable to walk
• Loss of mobility
• Vision impairment (early cataract formation)
• Swelling of the liver (hepatomegaly)
• Respiratory insufficiency
• Cognitive impairment
• Low self-esteem and depression
• Poor quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Pachyonychia Congenita Treated?

There is no cure for Pachyonychia Congenita since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops. The treatment methods may include:

• Proper hygiene and personal grooming practices
• Medication to manage pain
• Use of moisturizing creams and lotions
• Keratolytic agents
• Antibiotic or antifungal therapy, if necessary
• Nail care
• Debridement of rough and thick skin
• Aids to help with mobility, including crutches and wheelchairs
• Use of suitable footwear

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

How can Pachyonychia Congenita be Prevented?

Currently, Pachyonychia Congenita may not be preventable, since it is a genetic disorder.

• 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

What is the Prognosis of Pachyonychia Congenita? (Outcomes/Resolutions)

• The prognosis of Pachyonychia Congenita is dependent upon the severity of the signs and symptoms and associated complications, if any
• Although affected individuals have a normal lifespan, their quality of life may be poor due to the various complications that can develop resulting in chronic walking difficulties, poor functionality, and cognitive impairments

Additional and Relevant Useful Information for Pachyonychia Congenita:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/