Tricho-dento-osseous (TDO) syndrome is an autosomal dominant genetic disorder that belongs to a group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the hair, teeth, nails, and/or skin. TDO syndrome is characterized by kinky or curly hair; poorly developed tooth enamel; and unusual thickness and/or denseness (sclerosis) of the top portion of the skull (calvaria) and/or the long bones (i.e., bones in the arms and legs). In some cases, affected individuals also exhibit abnormally thin, brittle nails or premature closure (fusion) of the fibrous joints between certain bones in the skull (craniosynostosis), causing the head to appear abnormally long and narrow (dolicocephaly).

There may be three distinct types of TDO syndrome. Some researchers suggest that these variants may be differentiated mainly by whether the calvaria and/or long bones exhibit abnormal hardening (sclerosis), thickening, and/or density. Other symptoms also vary among the three disorder types.

TDO syndrome is characterized by abnormalities of the hair, teeth, bones, and/or nails. In addition, infants and children with TDO syndrome have tight, kinky or Curly hair that may also be unusually dry. As affected individuals enter their 20s or 30s, the hair may straighten or become unusually thin. Some individuals with the disorder also have unusually long eyelashes and eyebrows.

All individuals with TDO syndrome have Dental abnormalities that affect both the primary (deciduous) and secondary (permanent) teeth but the range of severity is extremely variable. The tooth enamel is underdeveloped (enamel hypoplasia), with diminished mineral accumulation (hypomineralization). As a result, the tooth enamel may be abnormally thin, soft, and pitted and often discolored (i.e., yellowish-brown). Hypersensitivity of the teeth is commonly reported. Both the primary and secondary molars may be abnormally shaped (i.e., “prism” shaped), and the chambers within the teeth that contain pulp may be abnormally large (taurodontism). In addition, many teeth may also have unusually short, open roots. As a result, the teeth may be highly prone to decay (dental caries) and infection (abscess) that may cause swelling and pain. Some affected individuals also exhibit widely spaced teeth; decreased tooth width (microdontia); premature (precocious) or delayed tooth eruption; and secondary teeth that become impacted in the gums. Affected individuals may lose their teeth early, typically in the second or third decade of life.

Some individuals with TDO syndrome also exhibit abnormalities of the nails. Fingernails and/or toenails may be unusually thin and brittle. In addition, the upper (superficial) layers of the nail may be prone to splitting.

Other reported abnormalities include impacted teeth and curvature of fingers (clinodactyly).

TDO syndrome is an autosomal dominant genetic disorder caused by a change (mutation) in the DLX3 gene. Several different mutations in the DLX3 gene have been reported. This gene is a member of the distal-less homeobox gene family. The disorder occurs because of a deletion in this gene that leads to a DLX3 protein product that is shorter than normal and does not function normally. Research has shown that the DLX3 gene plays a role in the patterning of the part of the embryo that leads to the formation of skin, teeth and ectoderm, as well as the formation of bones. This explains the presentation of the symptoms associated with TDO syndrome.

Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy. The risk is the same for male and female children.

The treatment of TDO syndrome is focused on the specific symptoms apparent in each individual and requires the coordinated efforts of a team of specialists. Pediatricians, specialists who diagnose and treat diseases of the bones (orthopedists), dental specialists and other health care professionals may be required to address the individual’s clinical symptoms.

Specific therapies for the treatment of TDO syndrome are symptomatic and supportive. Dental abnormalities associated with the disorder may be treated with a variety of techniques. Treatment is based on keeping teeth from wearing rapidly and exposing the pulp which causes abscess formation. Teeth can be treated with bonding and crowns to preserve the dentition. Dental specialists may obtain regular X-rays and take other steps to monitor dental development in the case of premature or delayed tooth eruption, to detect impacted secondary teeth and/or to help prevent, detect, and/or treat other dental abnormalities.

A variety of procedures may be used to restore improperly developed teeth to help prevent decay, abscess and/or early tooth loss. Artificial teeth and/or other devices (prosthetics) such as dental implants may be used to replace lost or absent teeth. In addition, dental surgery and/or other corrective procedures may be undertaken to correct other dental abnormalities.

Early intervention may be important to ensure that children with TDO syndrome reach their potential. Special services that may be beneficial to affected children may include special social support and other medical, social, and/or vocational services.

Genetic counseling is recommended for affected individuals and their families. Other treatment for this disorder is symptomatic and supportive.

Risk factors for TDO syndrome:

1. TDO syndrome is an autosomal dominant genetic illness that is part of a group of diseases known as ectodermal dysplasias.
2. Ectodermal dysplasias are conditions that affect the hair, teeth, nails, and/or skin.
3. Tricho-dento-osseous syndrome could be visible from birth due to the presence of kinky curly hair in all affected neonates with hair.
4. TDO syndrome is distinguished by kinky or curly hair, poor tooth enamel development, and unusual thickness and/or density (sclerosis) of the top region of the skull (calvaria), long bones, spine and jawThese skeletal deformities can be noticed in babies as young as three years old, although they become more evident with age.
5. Some of the youngsters who are affected also have abnormally thin, fragile nails. The majority of affected children have pretty typical head shapes, but some may have considerable deviation. TDO syndrome treatment focuses on the specific symptoms that each individual experiences.
6. TDO is caused by DLX gene family autosomal dominant mutations. A 4-base pair deletion in exon 3 of DLX3 on chromosome 17q21 results in a frameshift mutation.
7. Populations Affected: Tricho-dento-osseous syndrome is an inherited illness that affects both men and women equally. In the medical literature, around 12 affected families (kindreds) have been reported.

Symptoms
Abnormalities of the hair, teeth, bones, and/or nails
Conditions
TDO syndrome causes newborns and youngsters to have tight, kinky, or curly hair that is also unusually dry
Drugs
NA

In TDO syndrome, hair, teeth, and skeletal adverse effects are permanent, and treatment is needed to manage them. A patient with TDO shares the same lifespan as someone who does not have TDO. TDO has no treatments or drugs to treat its systemic effects, however, medications for ear and dental problems can be used to control its symptoms.

1. A collaborative strategy involving dental experts, oral and maxillofacial surgeons, and physicians is required to treat systemic consequences and enhance prognosis. It is also recommended that affected persons get counseling in order to better cope with any psychological problems caused by TDO's oral and facial abnormalities.
2. To control shedding and hair loss while at home, a patient with TDO may be instructed to utilize regular deep conditioning therapies and low-manipulation hair styling.
3. Radiology is used in clinical treatment to determine the effects of TDO on the underlying teeth and bone structures. To repair TDO anomalies, a series of meetings with the medical team is normally required, with treatment length ranging from several months to entire oral-facial development phases.
4. Endodontic operations are frequently advised to address tooth pulp exposure or periodontal abscess.
5. Maxillofacial surgery may be required to improve functioning by establishing a more adequate mastication, skeletal, and cosmetic relationship vertically between the teeth.
6. Dental crowns (dentistry) or veneers (dentistry) are frequently used to enhance the physical appearance of the teeth and to enhance the weak enamel produced by TDO.

Symptoms
Abnormalities of the hair, teeth, bones, and/or nails
Conditions
TDO syndrome causes newborns and youngsters to have tight, kinky, or curly hair that is also unusually dry
Drugs
NA