KRT6A and pachyonychia congenita: Taken together, these results confirm that the PC-associated p.Asn171Lys substitution results in profound impairment of K6a protein assembly, and reveal that the caries-associated p.Ser143Asn and p.Tyr497Cys substitutions in K6 proteins also affect the behavior of the proteins, when overexpressed in an ameloblast cell line.