What is Ectodermal Dysplasia?
Ectodermal dysplasias (EDs) are a broad range of inherited conditions that are identified by birth defects in two or more ectodermal structures – these are things like hair, teeth, nails, sweat glands – along with several other body parts that develop from the ectodermal, an early stage of an embryo. Such parts can include the mammary glands, central nervous system, the external ear, skin cells that produce pigment (melanocytes), the cornea (front covering of the eye), the conjunctiva (inner lining of the eyelid), and the lacrimal apparatus, the part of the eye that produces tears.
These conditions of ectodermal dysplasia have then been split into smaller groups by researchers PINHEIRO and FREIRE-MAIA, based on whether they showed problems with hair, nails, teeth, or sweat glands.
This way of organizing these conditions is referred to as the 1-2-3-4 system, as it separates the conditions into different groups based on which ectodermal structures are affected. Another way these conditions can be categorized is according to what genetic defects they have. The latest way of categorizing them takes into account everything from clinical symptoms to the genetic and functional elements of the conditions. This article provides a brief overview of the critical characteristics of a few ectodermal dysplasias for which we know the genetic cause.
What Causes Ectodermal Dysplasia?
Ectodermal dysplasias are genetic disorders that can be passed down in different ways. These disorders occur due to changes or mutations in a single gene that affect the processes responsible for the development of ectodermal structures (the outer layers of a developing embryo like skin, hair, nails, and teeth) and how they interact with mesodermal structures (the middle layers of a developing embryo that forms muscles, bones, blood vessels etc).
In simple words, when there are mutations in the genes that are responsible for the signaling within cells during development, it can lead to signal defects. These defects then lead to problems with the development of our body’s outer layer features coming from the ectoderm. This results in a lack of (aplasia), underdevelopment of (hypoplasia), or abnormal development of (dysplasia) these features like skin, hair, nails, etc.
One common example of this is hypohidrosis ectodermal dysplasia, where the affected individuals have trouble sweating (hypohidrosis) due to underdevelopment of sweat glands.
Risk Factors and Frequency for Ectodermal Dysplasia
Ectodermal dysplasia (ED), a disorder that usually affects the skin, sweat glands, teeth and hair, occurs in about 7 out of every 10,000 births worldwide. The most common type of ED is hypohydrotic ED, which often passes through families via the X chromosome. This type typically shows its full effects solely in males.
Signs and Symptoms of Ectodermal Dysplasia
Ectodermal dysplasias (EDs) are a group of disorders that affect the skin, hair, nails, and teeth. Here are some of the forms of this condition and their featured symptoms:
- Hypohidrotic Ectodermal Dysplasia: Common features of this condition can include sparse or absent hair, abnormal teeth, inability to sweat, frequent fevers, and distinctive facial features such as wrinkled skin around the eyes and a prominent forehead. Individuals might also experience recurrent respiratory infections, gastroesophageal reflux, and changes in voice. The features can vary in females due to the nature of X-inactivation.
- Hydrotic Ectodermal Dysplasia (Clouston Syndrome): This form mainly affects hair and nails, but not teeth or sweat glands. The hair is frail and sparse, while the nails might start small and discolored in infancy and thicken over time. Some might develop hyperkeratosis (thickening of the skin) on the palms and soles.
- Wiktop Tooth and Nail Syndrome: Individuals with this condition usually have brittle, slow-growing nails, and abnormal teeth. These abnormalities are often more common in the toenails. Both primary and secondary dentition can be affected.
- Ankyloblepharon-Ectodermal Defects-Cleft Lip/Palate Syndrome (Hay-Wells Syndrome): This form has symptoms at birth, often including a skin condition that results in peeling, as well as open sores. Other symptoms can include reduced sweating, abnormal teeth, chronic skin infections, and strands of tissue between the eyelids. Almost all patients present with a cleft palate with or without a cleft lip.
Testing for Ectodermal Dysplasia
If a patient shows signs of a condition called ectodermal dysplasia (ED), which involves abnormalities in the structure and function of skin, hair, nails, teeth, and sweat glands, they will undergo a thorough clinical evaluation. The healthcare provider will check for symptoms like an uncommon amount of sweating, or issues with their hair, nails, and teeth.
ED can be primarily diagnosed through this clinical exam, but to pin down the specific type of ED the person has, further tests may be necessary. One such test is a trichogram, a kind of hair analysis test. If the patient is suspected to have a form of ED known as hypohydrotic ED, this test could reveal “barcode hair” – a specific pattern seen under a microscope – which doesn’t show up if the patient has the hydrotic variant of ED.
Sometimes, a skin biopsy might be performed to confirm the diagnosis. In people with hypohydrotic ED, this test will show a lack of sweat-producing structures in the skin. In people with hydrotic ED, the test may show a condition called eccrine syringofibroadenomatosis, which is a rare benign tumor of sweat glands.
Lastly, X-rays of the limbs could also be useful. Though not necessarily required for diagnosis, they can help in identifying specific forms of ED.
Treatment Options for Ectodermal Dysplasia
To manage conditions affecting multiple organs, several strategies are typically used:
* Maintaining Healthy Body Temperature: It’s important to closely monitor body temperature, especially after exposure to heat. In older children, body-heating activities can be dealt with by drinking cold fluids regularly, using cooling equipment like special vests and hats.
* Dental Care: Starting dental treatment early can help improve the functionality and appearance of teeth. Procedures like bone grafting, sinus lift, dental implants, and prostheses are usually suggest under the guidance of a skilled orthodontist.
* Hair Growth: Recently, a medication called minoxidil (at a 3% concentration) has been used to promote hair growth in patients suffering from Hypohidrotic Ectodermal Dysplasias (HED, a rare genetic disorder).
* Skin Care: Skin-care ointments (emollients) are usually the first line of treatment for dry and scaly skin (xerosis), and a condition resembling a collodion baby, who is born with a shinny, tight skin. In patients with AEC syndrome, that causes skin erosions and long-term erosive scalp dermatitis, require meticulous wound care along with topical and oral antibiotics.
Apart from these, other abnormalities like limb defects and eye-related issues need to be addressed urgently through specialist consultation.
Overall, managing a group of rare genetic disorders known as ectodermal dysplasias (EDs) requires a coordinated, multi-pronged approach.
What else can Ectodermal Dysplasia be?
Ectodermal dysplasias (EDs) come in many types, and it’s crucial to correctly identify each one. Here are a few examples and what conditions they should be differentiated from:
- Hypohidrotic ED: With less severe symptoms, Sjogren syndrome should be considered. When the disease is fully developed, other ED types should be differentiated. If a newborn is experiencing high temperatures that get worse in an incubator and with neonatal phototherapy, you need to rule out unknown causes of fever.
- Hydrotic ED: This type, which typically involves changes to the nails paired with thickening of the skin on the palms and soles and white patches in the mouth, should be differentiated from pachyonychia congenita. Abnormal hair is the distinguishing feature in hydrotic ED, which closely resembles the pure hair-nail type of ED.
- AEC Syndrome: This syndrome is typically confused with either epidermolysis bullosa or bullous congenital ichthyosis. Rapp Hodgkin syndrome, which is now considered part of the AEC spectrum, does not usually present with ankyloblepharon (fusion of the eyelids). AEC also closely resembles CHANDS syndrome, which involves curly hair, ankyloblepharon, and nail dysplasia.
- EEC Syndrome: The main conditions similar to EEC are limb mammary syndrome and ADULT syndrome. Limb mammary syndrome is characterized by normal scalp hair and a lower incidence of cleft palate and absence of cleft lip, while ADULT syndrome is marked by prominent frontal hair loss, no clefting, and added photosensitivity. Other forms of ectodermal dysplasias that have digital abnormalities include ectodermal dysplasia, ectrodactyly maculo-dystrophy syndrome, Goltz syndrome, and popliteal pterygium syndrome.
What to expect with Ectodermal Dysplasia
Ectodermal dysplasias (EDs) are a group of genetic disorders affecting the development of tissues and structures derived from the outer layer of the embryo. If diagnosed early, people with ectodermal dysplasias usually lead a normal life in terms of lifespan. Timely and proper management of related dental and skeletal issues and adjusting body temperature in situations involving reduced sweat production, commonly seen in some types of these disorders, could greatly enhance these individuals’ quality of life.
Possible Complications When Diagnosed with Ectodermal Dysplasia
Hypohydrotic ectodermal dysplasias (EDs), a group of genetic disorders, can impair the skin’s capability to regulate body temperature. This can cause episodes of high body temperature, particularly in the first three years of life, and may increase the risk of death. Common problems in children with hypohydrotic ED include asthma, frequent upper respiratory tract infections, and atopic dermatitis, a type of skin inflammation.
Dental problems such as tooth decay or loss can cause difficulties with eating. Some variants of EDs, such as EEC syndrome, can lead to mental and physical developmental issues, and skeletal deformities that can result in disability. Ankyloblepharon, or the merging of the eyelids, and frequent infections of the tear-producing glands may cause complications affecting the eyes and sight.
Possible complications:
- Episodic high body temperature
- Asthma
- Recurrent upper respiratory tract infections
- Atopic dermatitis
- Tooth decay or loss
- Difficulty with eating
- Mental and physical developmental issues
- Skeletal deformities
- Eyelid deformities and eye infections
- Increased risk of early kidney failure due to genitourinary anomalies
In addition, recurrent skin infections and respiratory infections due to an impaired immune system can occur. These infections can increase the risk of serious health problems and death. In AEC syndrome, a specific kind of ED, persistent inflammation of the scalp could lead to scarring hair loss.
Preventing Ectodermal Dysplasia
Ectodermal dysplasias (EDs) are uncommon inherited skin conditions that come in many forms and affect parts of the body that grow from the ectoderm. Usually, these conditions show up in children. Hence, if there is a family history of similar conditions, it’s important that parents are aware about it and the signs that it can present. Parents should also know that their kids can live a normal life span as long as they are careful about regular check-ups and quickly seek medical help if any symptoms show up.
