Book syndrome

Alternate names

Premolar aplasia, hyperhidrosis, and canities prematura; PHC syndrome

Definition

Book syndrome is a very rare type of ectodermal dysplasia.

Epidemiology

To our knowledge, Book syndrome has only been reported in one, large Swedish family (25 cases in 4 generations) and in one other isolated case.

Cause

The cause is unknown.

Inheritance

• To our knowledge, Book syndrome has only been reported in one, large Swedish family (25 cases in 4 generations) and in one other isolated case.
• In the Swedish family, the syndrome was inherited in an autosomal dominant manner.
• In autosomal dominant inheritance, having a mutation in only one copy of the responsible gene is enough to cause signs and symptoms of the condition.
• When a person with an autosomal dominant condition has children, each child has a 50% (1 in 2) risk to inherit the mutated copy of the gene.

Signs and symptoms

• The signs and symptoms reported in the Swedish family included premolar aplasia (when the premolars fail to develop); excessive sweating (hyperhidrosis); and early whitening of the hair.
• Early whitening of the hair was the most constant symptom, being found in every affected family member.
• The age of onset of this symptom ranged from age 6 to age 23.
• In some cases, there was whitening of hair on other parts of the body such as the armipits, genital hair, and eyebrows. Two-thirds of the affected people had an abnormality of the sweat glands.
• In the isolated case, additional features that were reported include a narrow palate (roof of the mouth); hypoplastic (underdeveloped) nails; eyebrow anomalies; a unilateral simian crease; and poorly formed dermatoglyphics (skin patterns on the hands and feet).

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Hyperhidrosis(Excessive sweating)
• Hypodontia(Failure of development of between one and six teeth)
• Premature graying of hair(Early graying)
• Small hand(Disproportionately small hands)

30%-79% of people have these symptoms

• Abnormal eyebrow morphology(Abnormality of the eyebrow)
• Bilateral single transverse palmar creases
• Hypoplastic fingernail(Small fingernail)
• Narrow palate(Narrow roof of mouth)

Diagnosis

• Due to the rarity of Book syndrome and scarcity of reports in the medical literature, we are unaware of specific information about diagnosing Book syndrome.
• In general, ectodermal dysplasias are diagnosed by the presence of specific symptoms affecting the hair, nails, sweat glands, and/or teeth.
• When a person has at least two types of abnormal ectodermal features (e.g., malformed teeth and extremely sparse hair), the person is typically identified as being affected by an ectodermal dysplasia.
• Specific genetics tests to diagnose ectodermal dysplasia are available for only a limited number of ectodermal dysplasias.
• Unfortunately, there currently is no genetic test for Book syndrome because the gene responsible for the condition has not yet been identified.
• People who are interested in learning more about a diagnosis of ectodermal dysplasia for themselves or family members should speak with their dermatologist and/or dentist.
• These specialists can help determine whether a person has signs and/or symptoms of ectodermal dysplasia.

NIH genetic and rare disease info

• NIH info on Book syndrome

Book syndrome is a rare disease.

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