EEC syndrome is a genetic developmental disorder characterized by ectrodactyly, ectodermal dysplasia, and orofacial clefts (cleft lip/palate). The three cardinal signs of the syndrome are ectrodactyly and syndactyly of the hands and feet, cleft lip with or without cleft palate (that can result in speech defects), and abnormalities in several ectodermal structures including skin (i.e. hypopigmentated and dry skin, hyperkeratosis, skin atrophy), hair (i.e. fine and sparse hair and eyebrows), teeth (small, absent or dysplastic teeth), nails (nail dystrophy) and exocrine glands (reduction/absence of sweat, sebaceous and salivary glands). The syndrome presents a wide intra- and interfamilial clinical variability: the presence of the cardinal signs together is not mandatory and each one of them can be expressed in varying degrees of severity. Other associated clinical features include abnormalities of the genitourinary system (i.e. renal agenesis, urethral atresia, hydronephrosis), conductive or sensorineural hearing loss, choanal atresia, mammary gland/nipple hypoplasia, ophthalmological findings (i.e. lacrimal duct defects, photophobia, corneal ulcerations, keratitis, blepharitis, entropion), gland abnormalities (i.e. hypoplastic thymus, hypopituitarism, growth hormone deficiency), and on exceptional occasions, presence of a white sponge nevus, delayed developmental milestones, and malignant lymphoma. Patients do not have intellectual deficit.
The exact prevalence is not known. More than 300 cases have been described in the literature.