Other names: PC-16 (PC1), PC17 (PC2), PC6a (PC3), PC6b (PC4)

Photos courtesy of PC Project

OMIM: 167200, 167210, 615726, 615728

Inheritance: autosomal dominant

Incidence: rare

Key findings:

  • skin: thick, painful calluses on soles, less commonly on palms; variable redness around calluses
  • nails: thickened and hyperconvex
  • hair: no shaft abnormalities or alopecia

Inconstant: blisters, follicular keratoses, cysts, white patches in mouth, natal teeth

Associated findings: none

Age at first appearance: some, but not necessarily all, features present at birth.

Long-term course: lifelong; may worsen during first 20 years; generally stable thereafter Diagnostic tests: genetic testing is available

Abnormal gene(s): KRT6A; KRT6B; KRT6C; KRT16; KRT17


Clinicians seeking to confirm a diagnosis should visit FIRST's TeleIchthyosis site to submit a case to experts in ichthyosis.

To learn more about pachyonychia congenita, follow this link.

Learn more about FIRST's Regional Support Network -  connecting affected individuals and families with each other. Or call the FIRST office at 800.545.3286.


This information is provided as a service to patients and parents of patients who have ichthyosis.  It is not intended to supplement appropriate medical care, but instead to complement that care with guidance in practical issues facing patients and parents.  Neither FIRST, its Board of Directors, Medical & Scientific Advisory Board, Board of Medical Editors nor Foundation staff and officials endorse any treatments or products reported here.  All issues pertaining to the care of patients with ichthyosis should be discussed with a dermatologist experienced in the treatment of their skin disorder.

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