Oculodentodigital syndrome (ODD syndrome) is an extremely rare genetic condition that typically results in small eyes, underdeveloped teeth, and syndactyly and malformation of the fourth and fifth fingers. It has also been called oculo-dento-digital syndrome, oculodentodigital dysplasia (ODDD), and oculodentoosseous dysplasia (ODOD). It is considered a kind of ectodermal dysplasia

Ectodermal dysplasia

Ectodermal dysplasia is not a single disorder, but a group of syndromes all deriving from abnormalities of the ectodermal structures. More than 150 different syndromes have been identified. Despite some of the syndromes having different genetic causes the symptoms are sometimes very similar...

.

Signs and symptos

People with ODD syndrome often have a characteristic appearance. Visible features of the condition include:

• small teeth
  Microdontia
  Microdontia is a condition in which teeth appear smaller than normal. In the generalized form, all teeth are involved. In the localized form, only a few teeth are involved. The most common teeth affected are the upper lateral incisors and third molars...
  
   that are prone to caries
  Caries
  Caries is a progressive destruction of any kind of bone structure, including the skull, ribs and other bones, or the teeth. Caries can be caused by osteomyelitis, which is a microorganism disease. A disease that involves caries is mastoiditis, an inflammation of the mastoid process, in which the...
  
   because of underdeveloped
  Hypoplasia
  Hypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
  
   tooth enamel;
• a long, thin nose;
• unusually small eyes; and
• type III syndactyly
  Syndactyly
  Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and kangaroo, but is an unusual condition in humans.-Classification:...
  
   of the fourth and fifth fingers.

Iris atrophy and glaucoma

Glaucoma

Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...

 are more common than average. The size of the eyes often interferes with learning to read; special eyeglasses may be required. Hair may be fine, thin, dry, or fragile; in some families, it is curly.

Neurologic abnormalities may be seen in adults. The neurologic changes may appear earlier in each subsequent generation and can include abnormal white matter, conductive deafness, and various kinds of paresis

Paresis

Paresis is a condition typified by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it also can be used to describe the muscles of the eyes , the stomach , and also the vocal cords...

, including ataxia

Ataxia

Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...

, spastic paraplegia, difficulty controlling the eyes, and bladder and bowel disturbances.

Genetics

ODD is commonly an autosomal dominant condition, but can be inherited as a recessive trait. It is generally believed to be caused by a mutation in the gene GJA1

GJA1

-Interactions:Gap junction protein, alpha 1 has been shown to interact with MAPK7, Caveolin 1, Tight junction protein 1 CSNK1D, and PTPmu .-Further reading:...

, which codes for the gap junction protein connexin 43. Slightly different mutations in this gene may explain the different way the condition manifests in different families. Most people inherit this condition from one of their parents, but new cases do arise through novel mutations. The mutation has high penetrance

Penetrance

Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...

 and variable expression

Expressivity

Expressivity is a term used in genetics to refer to variations in a phenotype among individuals carrying a particular genotype. The term can be used to characterize qualitatively or quantitatively the extent of phenotypic variation given a particular genotype. The term is analogous to the...

, which means that nearly all people with the gene show signs of the condition, but these signs can range from very mild to very obvious.

Epidemiology

The actual incidence of this disease is not known, but only 243 cases have been reported in the scientific literature, suggesting an incidence of on the order of

Order of magnitude

An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

one affected person in ten million people.

External links

• Information from the ODDD Support Group
• Information from the Ectodermal Dysplasia Society
• About Ectodermal Dysplasia Types from the National Foundation for Ectodermal Dysplasias