A reduction in diameter of the distal phalanx of finger towards the distal end.

Onychodystrophy (nail dystrophy) refers to nail changes apart from changes of the color (nail dyschromia) and involves partial or complete disruption of the various keratinous layers of the nail plate.

Congenital anonychia is defined as the absence of fingernails and toenails. Anonychia and its milder phenotypic variant, hyponychia, usually occur as a feature of genetic syndromes, in association with significant skeletal and limb anomalies. Isolated nonsyndromic congenital anonychia/hyponychia is a rare entity that usually follows autosomal recessive inheritance with variable expression, even within a given family. The nail phenotypes observed range from no nail field to a nail field of reduced size with an absent or rudimentary nail (summary by Bruchle et al., 2008). This form of nail disorder is referred to here as nonsyndromic congenital nail disorder-4 (NDNC4). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).

The presence of developmental dysplasia of the nail.