Ectodermal dysplasias (ED) are a group of about 150 heritable disorders (non-progressive syndromes) that affect the ectoderm, a layer of tissue that contributes to the formation of many parts of the body, including the skin, sweat glands, hair, teeth, and nails. A predisposition to respiratory infections, due to a somewhat depressed immune system and to defective mucous glands in parts of the respiratory tract, is the most life threatening characteristic of this group of disorders.
Despite some of the syndromes having different genetic causes the symptoms are sometimes very similar. Diagnosis is usually by clinical observation often with the assistance of family medical histories so that it can be determined whether transmission is autosomal dominant or recessive.
Subdivisions of Ectodermal Dysplasias:
- Cloustons Syndrome:
Clouston syndrome is a form of ectodermal dysplasia that is characterized by abnormalities of the skin, hair and nails. Early signs and symptoms generally begin in infancy and may include nail abnormalities and sparse scalp hair that is wiry, brittle, patchy and pale. Progressive hair loss may lead to total alopecia by puberty. Affected people may also have palmoplantar hyperkeratosis (thick skin on the palms of the hands and soles of the feet), hyperpigmentation of skin (especially over joints) and/or clubbing of the fingers. Clouston syndrome is caused by changes (mutations) in the GJB6 gene and is inherited in an autosomal dominant manner. Treatment is based on the signs and symptoms present in each person.
- Palmoplantar Hyperkeratosis and Alopecia
- Anhidrotic X-Linked Ectodermal Dysplasias
- Book Syndrome
- Chaund's Ectodermal Dysplasias
- Chondroectodermal Dysplasias
- Christ-Siemans-Touraine Syndrome
- Curly Hair-Ankyloblephanon-Nail Dysplasia
- Dentooculocutaneous Syndrome
- Ectrodactyly Ectodermal Dysplasias Clefting Syndrome
- Ellis-van Creveld Syndrome
- Facial Ectodermal Dysplasias
- Freire-Maia Syndrome
- Gorlin's Syndrome
- Hidrotic Ectodermal Dysplasias
- Hypohidrotic Ectodermal Dysplasias, Autorecessive
- Hypoplastic Enamel-Onycholysis-Hypohidrosis
- Incontinentia Pigmenti
- Marshall's Ectodermal Dysplasias With Ocular nad Hearing Defects
- Naegeli Ectodermal Dysplasias
- Nail Dystrophy-Deafness Syndrome
- Oculodentodigital Syndrome
- Odontotrichomelic Syndrome
- Onychotrichodysplasia with Neutropenia
- Oral-Facial-Digital Syndrome (Type I)
- Otodental Dysplasia
- Pachyonychia Congenita
- Rapp-Hodgkin Hypohidrotic Ectodermal Dysplasias
- Robertson's Ectodermal Dysplasias
- Rosselli-Gulienatti Syndrome
- Schopf-Schultz-Passarge Syndrome
- Stevanovic's Ectodermal Dysplasias
- Tooth and Nail Syndrome
- Trichodento Osseous Syndrome
- Trichorhinophalangeal Syndrome
- Triphalangeal Thumbs-Hypoplastic Distal Phalanges-Onychodystrophy
- Witkop Ectodermal Dysplasias
- Xeroderma, Talipes, and Enamel Defect
People with ectodermal dysplasia may not sweat or may have decreased sweating because of a lack of sweat glands. Children with the disease may have difficulty controlling fevers. Mild illness can produce extremely high fevers, because the skin cannot sweat and control temperature properly. Affected adults are unable to tolerate a warm environment and need special measures to keep a normal body temperature.
Other symptoms include:
- Abnormal nails
- Abnormal or missing teeth
- Absent or very thin hair (Sparse)
- Absent or decreased tears
- Decreased skin color (pigment)
- Foul-smelling nasal discharge
- Heat intolerance
- Inability to sweat
- Large forehead
- Light coloring
- Lower than normal number of teeth
- Low nasal bridge
- Poor hearing
- Poor temperature regulation
- Poor vision
- Thin hair
- Thin skin
- Poorly functioning sweat glands
- Sparse or absent hair follicles
- Abnormal hair
- Disfigured nails
- Difficulties with the nasal passages and ear canals
- Skin is satiny smooth, prone to rashes, and slow to heal
- Commonly, the teeth fail to develop properly
- Hearing deficit
- Loss of sight
- Mental retardation
- Limb abnormalities
- Cleft palate and lip
- Urinary tract anamolies
- Allergies are common, as are bronchitis and pneumonia
All of the ectodermal dysplasias are hereditary. They are caused by alterations (mutations) in various genes; the mutations may be inherited from a parent, or normal genes may become mutated at the time of egg or sperm formation, or after fertilization. The risk for parents to have an affected child depends on the inheritance pattern of the specific type of ectodermal dysplasia with which the individual in the family has been diagnosed. Thus, a family affected by an ectodermal dysplasia should consider speaking with a geneticist or a genetic counselor for a better understanding of the specific ectodermal dysplasia and the probabilities or risks that the ectodermal dysplasia will occur in any future pregnancy.
The different types of inheritance patterns that occur depending on the specific type of ectodermal dysplasia in the family include X-linked recessive, autosomal dominant, and autosomal recessive.
- X-linked recessive: If a woman is a carrier of an X-linked recessive form, there is a 50% chance that each of her male children will receive the abnormal gene and be affected, and a 50% chance that each female will receive the abnormal gene and be a carrier (like the mother). If a man has the abnormal gene, he will definitely be affected and will also pass the gene on to all of his daughters, who will be carriers. Since the gene is on the X chromosome, his sons will not be affected because they receive the man's Y chromosome.
- Autosomal dominant: When the ectodermal dysplasia is an autosomal dominant form, the parent who is affected has a single copy of the abnormal gene (which is sufficient to cause the disorder in any autosomal dominant condition) and may pass it on to his or her children. Regardless of the gender of the parent or the child, there is a 50% chance for each child to receive the abnormal gene and be affected, and a 50% chance to not inherited the abnormal gene. All children who receive the abnormal gene will be affected.
- Autosomal recessive: When the ectodermal dysplasia in the family is an autosomal recessive form, the usual situation is that each parent is unaffected, but likely has one mutated copy of the gene and one normal copy of the gene. They are said to be carriers. Carriers do not typically show signs and symptoms of an autosomal recessive condition. When two parents who are carriers have children, with each pregnancy there is a 25% (1 in 4) risk for the child to have the condition, a 50% (1 in 2) risk for the child to be an unaffected carrier like each of the parents, and a 25% chance for the child to not have the condition and not be a carrier (and therefore not pass the mutation on to future generations). To be affected with an autosomal recessive condition, an individual must have two abnormal copies of the causative gene.
Sometimes, when an individual is the first person in a family to be affected with an ectodermal dysplasia, it is because a new mutation occurred in that individual, and neither of the parents carry an abnormal copy of the gene. Usually, in this case, there is little chance that it will occur in another child of the same parents. However, the affected child may transmit the abnormal gene to future generations.
Individuals who have questions about their own genetic risks or status, or risks to current and future family members, should speak with a genetics professional.
If you have a family history of ectodermal dysplasia and you are planning to have children, genetic counseling is recommended. In many cases it is possible to diagnose ectodermal dysplasia while the baby is still in the womb.
- Biopsy of the mucus membranes
- Biopsy of the skin
- Genetic testing (available for some types of this disorder)
Having ectodermal dysplasia will not shorten your life span, but you must pay constant attention to temperature regulation and other problems associated with this condition.
No cure for the underlying causes of Ectodermal Dysplasia is known. Treatment is directed at symptoms. Over the counter creams may relieve skin discomfort. Dentures, hearing aids, etc. may be required. Heat and over- exercise are avoided. Vaccines and anti-infectious agents are used to reduce infections of skin and respiratory tract. Cleft palate and lip, syndactyly, and other limb deformations are treated by surgery.Precautions should be taken to minimize the effects of overheating while exercising or in warm temperatures.