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At a glance

A disorder with nail dysplasia and bone abnormalities.


Anonychia-Onychodystrophy with Hypoplasia/Absence of Distal Phalanges.


Unknown. Extremely rare disorder described in 19 patients, 11 of them members of two unrelated families.

Genetic inheritance

Autosomal dominant. In some patients, microduplications on chromosome 17q24.3, a non-coding element of the SOX9 (SRY-box 9) gene, have recently been implicated in Cooks Syndrome.


Based on the characteristic clinical findings and family history.

Clinical aspects

Characterized by onychodystrophy, hyponychia, or anonychia that can affect some or all digits of hands and feet. In some patients, nail hypoplasia of the hands was progressive from digit I to III, while digits IV and V showed anonychia. Uni- or bilateral digitalization of the thumbs appearing long and bulbous. Also present are fifth finger brachydactyly of the hands, hypoplastic, or absent distal phalanges of hands. On the feet there was total absence of all distal phalanges of digits II through V and hypoplasia of the distal phalanx of the hallux. Abnormal dermatoglyphic pattern is common. However, the spectrum of distal phalangeal hyponychia/anonychia is very variable, even within the same family. Cutaneous syndactyly or symphalangism may be present. The features of hands and feet are also present in brachydactyly Type B, but this disorder may also include mild facial dysmorphism with downslanting of the palpebral fissures, high nasal bridge, prominent nose with bulbous tip, hypoplastic alae nasi, and short philtrum and high-arched palate. Some experts consider Cooks Syndrome and Brachydactyly Type B to belong to the same entity, whereas others consider them to be two different conditions.

Precautions before anesthesia

Facial dysmorphism is mild and is not expected to affect airway management. Routine preoperative assessment is considered adequate.

Anesthetic considerations

No specific anesthetic concerns are expected to arise from this disorder.

Other condition to be considered

  • Coffin-Siris Syndrome: Congenital syndrome with growth and mental retardation, coarse facies, nail dysplasia, and skeletal anomalies.


Brennan  CB, Buehler  T, Lesher  JL Jr: Cooks syndrome: A case report and brief review. Pediatr Dermatol 30(4):e52–53, 2013.  [PubMed: 22329539]
Castori  M, Brancati  F, Mingarelli  R,  et al: A novel patient with Cooks syndrome supports splitting from “classic” brachydactyly type B. Am J Med Genet A 143A(2):195–199, 2007.  [PubMed: 17163524]
Chatterjee  D: Congenital anonychia and brachydactyly of the left foot—Cooks syndrome variant: Case report and review of literature. Indian J Hum Genet 20(2):206–208, 2014.  [PubMed: 25400355]
Cooks  RG, Hertz  M, Katznelson  MB,  et al: A new nail dysplasia syndrome with ...

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