The ectodermal dysplasias are a group of disorders characterized by anomalies of the epidermis and its appendages, such as the hair, teeth, nails, and sweat glands.

Odontotrichomelic syndrome (OS) is an extremely rare type of ectodermal dysplasia with associated severe deformities of all 4 extremities. Fewer than 5 cases have been reported to date. Clinical findings include variable aplasia of the long bones of the extremities and digits, and of the patella, onychodysplasia, deformed auricles, hypotrichosis, abnormal dentition, hypoplastic or aplastic nipples and areolae, and nasolacrimal duct atresia. Other features include hypogonadism, thyroid enlargement and dysfunction, and intellectual disability. ECG and electroencephalogram (EEG) abnormalities as well as elevated levels of tyrosine and/or tryptophan in the urine have also been reported.

OS is thought to demonstrate an autosomal recessive mode of inheritance.