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Features include sometimes findings: Oral leukoplakia. 4 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Skin | 2 | Plantar hyperkeratosis, Palmoplantar keratoderma |
Blood and immune system | 1 | Oral leukoplakia |
In all types of pachyonychia congenita (PC) most characteristics are visible by age ten years and typically include toenail thickening, plantar keratoderma, and plantar pain . However, the absence or presence of certain features as well as the age at onset varies according the gene that is mutated (see for phenotypic features of PC). The most recent classification of the condition also incorporates the genetic cause . The severity of findings can differ both within a family and among families with the same pathogenic variant.
Table 2.
International Pachyonychia Congenita Research Registry (IPCRR) Data Summary (as of 10 May 2017)
Gene in Which PathogenicVariants Were Confirmed | KRT6A | KRT6B | KRT6C | KRT16 | KRT17 | TOTAL
| 304 | 71 | 22 | 247 | 130 | 774
Source: GeneReviews — "Pachyonychia Congenita"
KRT6C encodes keratin 6C (564 aa). Highest expression in Esophagus Mucosa (548.2 TPM) and Vagina (114.9 TPM).
Palmoplantar keratoderma, nonepidermolytic, focal or diffuse is associated with mutations in the KRT6C gene on chromosome 12.
KRT6C is classified as a druggable target with score 0.0.
Based on data on 774 individuals with PC in the IPCRR, clear genotype-phenotype correlations are evident . In the following instances, the phenotype may vary among individuals with the same pathogenic variant:
Source: GeneReviews — "Pachyonychia Congenita"
Clinical diagnostic criteria for pachyonychia congenita (PC) include the triad of toenail thickening, plantar keratoderma, and plantar pain, which are present in 97% of individuals with genetically confirmed PC by age ten years [International Pachyonychia Research Registry, ].
Pachyonychia congenita (PC) should be suspected in individuals with the following clinical features and/or family history findings.
Clinical features
Source: GeneReviews — "Pachyonychia Congenita"
Onychomycosis. While the hyperkeratotic nail thickening seen in pachyonychia congenita (PC) may be mistaken for onychomycosis, dermatophytic infections do not affect all finger and toenails, particularly at an early age. In the rare conditions of autoimmune endocrinopathy-candidiasis-ectodermal dystrophy (APECED) and systemic mucocutaneous candidosis, all nails may be affected. Oral leukokeratosis together with nail dystrophy is often an indication of pachyonychia congenita and may be mistaken for Candida albicans (thrush), white sponge nevus, and/or leukoplakia. Epidermolysis bullosa simplex (EBS) or other palmoplantar keratodermas can result in a similar pattern of plantar blister formation or hyperkeratosis, respectively; however, they do not share the characteristic nail changes of PC.
Source: GeneReviews — "Pachyonychia Congenita"
Genetic testing for KRT6C is available. Testing is considered confirmatory for diagnosis.
Biomarker and diagnostic research for palmoplantar keratoderma, nonepidermolytic, focal or diffuse has been reported in the published literature.
No approved treatments are currently available for palmoplantar keratoderma, nonepidermolytic, focal or diffuse. The disease remains an area of unmet medical need.
To establish the extent of disease and needs in an individual diagnosed with pachyonychia congenita, the following evaluations are recommended:
Thorough clinical examination to assess each affected area. These will vary based on the specific gene involved and may need to be repeated once genetic testing is completed in order to fully understand the phenotype of the affected individual.
Consultation with a clinical geneticist and/or genetic counselor
Preliminary treatment guidelines have been published and continue to be refined. The current treatment modalities primarily center on symptomatic relief of pain, hygienic grooming practices including paring of hyperkeratotic areas, treatment of secondary infection when indicated, and use of various walking aids including wheelchairs, crutches, and canes. Palmoplantar keratoderma. Frequent grooming of the feet is essential and includes paring down the hyperkeratotic areas. However, trimming too aggressively can greatly increase pain. Some find it helpful to soak the feet prior to the paring. The surface of the skin and the instruments used should be clean to avoid infection. Blisters should be punctured with a sterile needle, the fluid drained, and the blister roof left in place until it dries and is shed away. Topical therapies to remove the hyperkeratosis:
Source: GeneReviews — "Pachyonychia Congenita"
Some report that higher temperatures and higher humidity worsen the condition.
Source: GeneReviews — "Pachyonychia Congenita"
In 2014, a Phase 1b clinical trial sponsored by PC Project and TransDerm was performed using topical sirolimus. This study included 15 affected individuals and was conducted by Dr Joyce Teng at Stanford University. Background research for this trial was previously published . Short interfering RNA (siRNA) can selectively block expression of a specific K6a-causing pathogenic variant . The siRNA trial included treatment of a single individual with a specific KRT6A pathogenic variant in a dose-escalation trial of an siRNA directed against the p.Asn171Lys mutated allele . The affected individual did not experience any adverse effects from the experimental treatment. The affected person also experienced callus regression on the foot treated with siRNA.
Source: GeneReviews — "Pachyonychia Congenita"
View trials for palmoplantar keratoderma, nonepidermolytic, focal or diffuse
In general, individuals with PC have no known associated systemic diseases or predispositions that require routine surveillance.
Source: GeneReviews — "Pachyonychia Congenita"
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for palmoplantar keratoderma, nonepidermolytic, focal or diffuse.
200 publications have been identified in PubMed for palmoplantar keratoderma, nonepidermolytic, focal or diffuse. Research spans Basic Science / Preclinical (86%), Diagnostic / Biomarker (4%), and Review / Meta-Analysis (4%).
Research Type | Count | % of Total |
|---|---|---|
Laboratory research | 171 | 86% |
Testing and diagnosis research | 8 | 4% |
Research summaries | 7 | 4% |
New treatment approaches | 5 | 3% |
Other research | 3 | 2% |
Disease patterns and progression | 3 | 2% |
Clinical study results | 2 | 1% |
Scott A (2026). [PMID: 41689527](https://pubmed.ncbi.nlm.nih.gov/41689527/). *Nano letters*. [Basic Science / Preclinical]
Dhara P (2026). [PMID: 41494299](https://pubmed.ncbi.nlm.nih.gov/41494299/). *Journal of physics. Condensed matter : an Institute of Physics journal*. [Basic Science / Preclinical]
Paul A (2026). [PMID: 41368896](https://pubmed.ncbi.nlm.nih.gov/41368896/). *Physical chemistry chemical physics : PCCP*. [Basic Science / Preclinical]
Moretti D (2026). [PMID: 41758023](https://pubmed.ncbi.nlm.nih.gov/41758023/). *Soft Matter*. [Basic Science / Preclinical]
Stelzl C (2026). [PMID: 41533433](https://pubmed.ncbi.nlm.nih.gov/41533433/). *Lab on a chip*. [Basic Science / Preclinical]
Losa J (2026). [PMID: 41966684](https://pubmed.ncbi.nlm.nih.gov/41966684/). *Mol Cell*. [Basic Science / Preclinical]
Tyson JJ (2026). [PMID: 41945190](https://pubmed.ncbi.nlm.nih.gov/41945190/). *Bull Math Biol*. [Review / Meta-Analysis]
Nakashima IF (2025). [PMID: 41329740](https://pubmed.ncbi.nlm.nih.gov/41329740/). *Proceedings of the National Academy of Sciences of the United States of America*. [Basic Science / Preclinical]
Li Q (2025). [PMID: 40532877](https://pubmed.ncbi.nlm.nih.gov/40532877/). *Biophysical reports*. [Basic Science / Preclinical]
Emon S (2025). [PMID: 40425985](https://pubmed.ncbi.nlm.nih.gov/40425985/). *J Biol Phys*. [Basic Science / Preclinical]
Data assembled from 7 of 12 sources · Last updated Sep 17, 2026, 10:07 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center