Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

At a glance

A rare form of ectodermal dysplasia with premolar aplasia, hyperhidrosis, premature cavities, and premature whitening of the hair.


PHC Syndrome (the name used by Böök himself) Premolar Aplasia, Hyperhidrosis, Premature Cavities Syndrome.


The syndrome bears the name of the Swedish geneticist J. A. Böök, who first reported this disorder in 1950.


Unknown, but extremely rare. Böök described 25 patients from 4 Swedish families consisting of 172 members.

Genetic inheritance

Autosomal dominant with high penetrance.


Unknown, but Böök Syndrome belongs to the heterogeneous group of Ectodermal Dysplasias that includes more than 150 diseases with various inheritance modes and genetic heterogenicity. In Ectodermal Dysplasia, the common denominator seems to be a perturbation of epithelial morphogenesis.


Based on the clinical picture with premature whitening of hair, characteristic dental defects, and family history.

Clinical aspects

The dental abnormality is the most frequent sign. Hypodontia of the premolars is constant, while the number of them missing is variable. Anodontia or oligodontia are occasionally observed. Abnormal dental position and tooth shape may be observed. Premature whitening of hair can already start in childhood (before the age of 10 years) and by the age of around 20 years, the hair is often completely white. Decreased or absent pigmentation in genital and axillary hair has been described but is not common. The premature graying may occur in connection with poorly formed dermatoglyphics and distal digital creases. Pigmentation of skin, eyebrows, and eyelashes is normal. Increased, often disabling sweating (hyperhidrosis) of hands and feet (and occasionally forehead and axilla) is very common (in two-thirds of patients).

Precautions before anesthesia

No other disorders are associated with this particular syndrome. However, due to mild depression of the immune system and a defect in the respiratory mucous glands associated with other forms of Ectodermal Dysplasia, a predisposition to respiratory tract infections, which are potentially life-threatening, has been described. No such reports exist specifically for this PHC Syndrome, but nevertheless it should be kept in mind when assessing these patients (some of the patients reported by Böök had chronic tuberculosis, one had hepatitis). Evaluate dental position, aspect and mobility, and severity of hyperhidrosis.

Anesthetic considerations

No reports with regards to anesthetic care with these patients are available. Patients may present for surgical management of hyperhidrosis. Extremity lesions can interfere with pulse oximetry. Direct laryngoscopy must be performed very carefully due to the dental anomalies.

Pharmacological implications

Hyperhidrosis must be evaluated before use of ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.