Anonychia-onychodystrophy with hypoplasia or absence of distal phalanges




This syndrome, designated as Cooks syndrome, is characterized by nail anomalies ranging from onychodystrophy (dystrophic nails) to anonychia (absence of nails), associated with brachydactyly of the fifth finger, and digitalization of the thumbs (triphalangism). Eleven cases have been described in the literature so far. The distal phalanges of the hands and feet are either absent or hypoplastic. Among the 11 described cases, seven of the patients came from two generations of the same family with one instance of male-to-male transmission, and the other four patients came from three successive generations of another family with again an instance of male-to-male transmission. These observations suggest an autosomal dominant mode of inheritance. The syndrome should be distinguished from other nail disorders such as autosomal dominant anonychia-onychodystrophy: anonychia-onychodystrophy is not associated with bone changes and the nail hypoplasia is progressive from the fifth digit to the thumb, with anonychia often present in the second and third digits, whereas the nail hypoplasia in the thumb of patients with anonychia-onychodystrophy with hypoplasia or absence of the distal phalanges progresses to total nail absence in the fourth and fifth digits. In autosomal dominant brachydactyly with absence of the middle phalanges and hypoplastic nails, the changes in the middle phalanges are distinctive. In anonychia with ectrodactyly, digital anomalies are asymmetric, including absence of one or more digits. In '20-nail dystrophy', dystrophy of the nails progresses with age, whereas in patients with anonychia-onychodystrophy with hypoplasia or absence of the distal phalanges syndrome the nail findings are present from birth


  • Abnormality of the fingernails
  • Anonychia
  • Aplastic/hypoplastic toenail
  • Brachydactyly syndrome
  • Split hand
  • Triphalangeal thumb


  • NIH