Ectodermal Dysplasia is not a single disorder, but a group of closely related disorders known as the Ectodermal Dysplasias. The term ectoderm refers to some of the earliest cells found in a baby. Very early in development a baby, at this stage the embryo, consists of 3 types of cell – endoderm, mesoderm and ectoderm. The cells of the ectoderm go on to form teeth, hair, nails and sweat glands as well as a few other types of cells. The term dysplasia means a change from the usual pattern of growth. Therefore, the term Ectodermal Dysplasia is a descriptive term meaning an individual has changes in the structure of parts of the body that have developed from the ectoderm.
The Ectodermal Dysplasias are genetic disorders affecting the development or function of the teeth, hair, nails and sweat glands. More than 180 different types of Ectodermal Dysplasia have been identified. Depending on the particular type (syndrome), an Ectodermal Dysplasia can also affect the skin, the eyes or ears, the lining of the airways, the development of fingers and toes, the nerves and other parts of the body.
Each type usually involves a different combination of symptoms, which can range from mild to severe, such as:
- Absence or abnormality of hair growth.
- Absence or malformation of some or all teeth.
- Impairment in the development of many glands, especially sweat glands, but also salivary glands (make saliva), lacrimal glands (make tears), mucous glands and the breasts.
- Lack of the ability to sweat causes overheating.
- Too little production of tears and other protective secretions of the eyes. This can make them sensitive and even painful.
- Reduced production of mucus in the airways, that leads to chest infections and – in those exposed too often to smoke or dust – to chronic lung damage (emphysema).
- Impairment or loss of hearing.
- Nasal blockage due to a build-up of secretions.
- Frequent infections due to immune system deficiencies and, in some cases, the inability to keep bacteria from entering the body through cracked or eroded skin.
- Less effective barrier properties of the skin, airways and gut leading to infections and to allergies (e.g. asthma, eczema and hay-fever).
- Respiratory problems: not only asthma and chest infections but also, in those who smoke or are exposed to dust, a severe form of chronic chest disease (may be diagnosed as emphysema or as pneumoconiosis).
- Absence or malformation of some fingers or toes.
- Cleft lip and/or palate.
- Irregular skin pigmentation.
In addition to the above individuals affected by Ectodermal Dysplasia may have:
- Sensitivity to light.
- A lack of breast development.
- Psychological challenges due to changes in physical appearance.
Individuals affected by Ectodermal Dysplasia may face a lifetime of special needs.
These can include:
- Dentures at a young age with frequent adjustments and replacements.
- Osseointegrated dental implants.
- Special diets to meet dental/nutritional needs.
- Air-conditioned environments.
- Wigs to conceal the lack of hair and scalp conditions.
- Creams or devices to protect from direct sunlight.
- Respiratory therapies for asthma and infections.
Ectodermal dysplasia usually occurs because of a change in an individual’s DNA. The individual with ectodermal dysplasia may be the first person in the family to have the genetic change or the change, may have been inherited from a family member. Not all ectodermal dysplasias are passed on in families in the same way.
(See section on Genetic Inheritance Patterns for more detail).
When questions about a diagnosis exist, the expertise of a geneticist or other doctor/dentist with experience of the Ectodermal Dysplasias is strongly recommended.
It is important to remember that not all individuals affected by the Ectodermal Dysplasia will have physical features that fit the description of a specific syndrome. All individuals are different and there may be a great deal of variation in the physical appearance between one affected person to the next with the same type of Ectodermal Dysplasia even within the same family. We do not yet understand all the causes of Ectodermal Dysplasia and so it is conceivable for a person to have a type of Ectodermal Dysplasia that has not yet been described. Nonetheless, the Ectodermal Dysplasias share certain features, an understanding of which makes it possible to appreciate the ramifications for most affected individuals and allows everyone involved to respond appropriately to the individual’s needs.