The book syndrome is a rare autosomal dominant (with high penetrance) form of ectodermal dysplasia which was first described in four generation of a Swedish family (25 patients) with premature graying of hair, hyperhidrosis, and premolar aplasia (Böök 1950). Early whitening of the hair was the most frequent symptom found in every affected family member. In some cases, there was whitening of hair on other parts like the axillary region, groin hair, and eyebrows. Two-thirds of the affected patients also had malformation of the sweat glands resulting in hyperhidrosis (Böök 1950).