Tricho-dento-osseous syndrome

Tricho-dento-osseous syndrome (TDO syndrome) is a rare autosomal dominant genetic disorder characterized by abnormalities affecting the hair (tricho-), teeth (dento-), and bones (osseous). It is caused by mutations in the DLX3 gene located on chromosome 17q21, which encodes a transcription factor important for the development of hair, teeth, and bone. TDO syndrome is sometimes considered part of the spectrum of amelogenesis imperfecta syndromes, but it is distinguished by its multisystem involvement. The hallmark features of TDO syndrome include kinky, curly, or coarse hair at birth (which may straighten over time), severe enamel hypoplasia and hypomaturation leading to discolored, pitted, and thin tooth enamel, taurodontism (enlarged pulp chambers in the teeth), and increased thickness and density of the cranial bones (sclerosis of the skull). Affected individuals frequently experience dental problems including increased susceptibility to cavities and tooth abscesses due to the enamel defects. Nail abnormalities, such as brittle or splitting nails, may also be present. Bone density may be generally increased (osteosclerosis), particularly in the skull, though this is usually asymptomatic. There is no cure for TDO syndrome, and management is primarily supportive and symptomatic. Dental care is a major focus of treatment, often requiring extensive restorative work including crowns, dental implants, and management of recurrent abscesses. Early and regular dental follow-up is essential. Genetic counseling is recommended for affected families given the autosomal dominant inheritance pattern, meaning each child of an affected individual has a 50% chance of inheriting the condition. The condition shows variable expressivity, meaning the severity of features can differ significantly even within the same family.

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