Bone dependent nail formation

Abstract

Two sporadic cases with congenital anonychia and hypoplastic nails combined with ectrophalangia or hypoplastic phalanges are reported. It is suggested that congenital anonychia and hyponychia may be 'bone territory' dependent disorders.

Congenital complete simple anonychia

“…It is frequently an incomplete and randomly distributed absence of fingernails and toenails [1,6]. Baran and Juhlin stated that the development of a normal nail is dependent on the underlying bone and anonychia was suggested to occur when the underlying bone was either hypoplastic or completely absent [2]. Our case has supported this hypothesis since distal phalangeal bones were absent in the fifth digits of both hands, and the other distal phalangeal bones of both hands were hypoplastic.…”

“…Congenital complete anonychia (congenital absence of nails on all fingers and toes) is a much rarer form of this anomaly [7]. Anonychia may result when the underlying bone is either hypoplastic or completely absent [2].…”

Dizygotic twins with congenital malalignment of the great toenails: Reappraisal of the pathogenesis

“…27,28 As a result the size of the nail is dependent on the size and the shape of the distal phalanx, and, more generally, nail formation largely depends on proper distal phalanx formation. 27 Recent evidence suggests that spatial and chronological coordination in the expression of key developmental genes of the morphogenesis of structures originating from both mesoderm and ectoderm is mandatory for the proper formation of the end phalanx of mammalian fingers (for a recent review see Seitz and Hamm 29 ). According to the proposed pathogenesis (see Fig 4), the bony phalanx remains temporarily smaller relative to the overlying nail plate as a result of partial desynchronization of morphogenic processes.…”

Circumferential Nail

“…Baran and Juhlin [12] proposed that nail development is bone dependent, possibly explaining the coexistence of nail and bone abnormalities in many cases. In our patient, there was an absence of any bony structures in the centre of the CN as seen on X-ray.…”