Pseudofollicultis Barbae (PFB) is a vexing chronic disorder common in those of African descent and often exacerbated by shaving. Those African Americans who must be clean shaven for their occupation may suffer disproportionally. PFB is very highly associated with a polymorphism in keratin of the hair sheath, KRT75. KRT75 is in the companion layer of the root sheath and also in the medulla. (A different mutation is responsible for the loose anagen syndrome.) Duverger et al report that teeth, and especially their enamel, contain KRT75; even more remarkably, the polymorphism coding mutation of PFB is associated with increased dental cavities in a European-derived population (Duverger et al, 2014). Teeth with the PFB polymorphism have decreased hardness, leading to pits and holes in which oral bacteria can grow and produce the acids involved in cavity formation. Adults with the mutation had increased cavities, but children with the mutation did not. More questions to be investigated.
Bringing the world and science of teeth and hair together in a carefully performed study is an outstanding example of how biology bridges the diseases of many organs and once again demonstrates the need for scientists and clinicians to have broad biological views. Further studies of African –American populations studying both cavities and PFB are no doubt planned or are in progress.