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Common findings of pachyonychia congenita include: thickened and dystrophic nails (both fingernails and toenails) (a-c); bullae (usually on the pressure points of the heels and soles); hyperkeratosis (d-e); cysts (f); and oral leukokeratosis (g).

Schematic diagram showing the basic protein structure of a keratin filament. The α-helical rod domain is divided into four domains: 1A, 1B, 2A, and 2B, connected by non-helical linkers L1, L12, and L2. At the ends of the rod domain are the helix initiation motif (shaded red) and helix termination motif (shaded red) that are highly conserved in sequence between keratins. The majority of pathogenic variants found in PC in KRT6A, KRT6B, KRT6C, KRT16, and KRT17 fall within these highly conserved domains.