It's all in the family
XLHED, or X-linked hypohidrotic ectodermal dysplasia, is a rare genetic disorder that runs in families. See how families have come to understand what it means to live with XLHED. Watch the video:
What causes XLHED?
XLHED is caused by a change in a gene that is passed from parents to children on the X chromosome. Chromosomes are "messengers" that carry "instructions" (genes) to the body in cells. In XLHED, there is a change in instructions this gene delivers which causes it not to fully function. XLHED is also known as Christ-Siemens-Touraine syndrome.
A change in a gene called EDA may result in XLHED. This gene controls the production of proteins (molecules the body needs for growth) that work together to develop the skin, hair, nails, teeth, and sweat glands. But when the gene is changed, there is not enough protein for typical development of these tissues and organs.
How is XLHED inherited?
The changed gene that causes XLHED is carried on the X chromosome. Chromosomes are threadlike structures that carry genetic material in cells. X and Y chromosomes are called the sex chromosomes. Women have two X chromosomes, while men have one X and one Y chromosome.
Can mothers affected by XLHED pass the gene for XLHED to their children?
A woman with XLHED, or a "carrier", has a gene that has been changed. Women who are carriers for XLHED may also have some symptoms of XLHED, or they may have mild or even severe versions of them. The way each woman experiences symptoms of XLHED is unique.
Since women have two X chromosomes, when one X is changed, the unchanged X can help compensate. This unchanged copy can partially (or fully in some cases) control the development of some, or all, of the skin, hair, nails, teeth, and sweat glands. This helps women have less severe XLHED symptoms than men.
There is a 50% chance that a woman who is a carrier for XLHED will pass the gene on to her son. Sons who inherit this gene will be affected by XLHED. This is because their only copy of the XLHED gene on the X chromosome does not work correctly. If the woman that is a carrier has a daughter, there is a 50% chance the daughter will inherit the changed gene. Then she can also pass XLHED to a future child, like her mother did.
Can fathers affected by XLHED pass the gene for XLHED to their children?
Fathers pass their X chromosome to their daughters and the Y chromosome to their sons. Because the changed gene for XLHED is only on the X chromosome, fathers with XLHED will pass the changed gene to all of their daughters. Daughters may then pass the changed gene to their unborn child. Fathers cannot pass this gene to their sons, because they pass the Y chromosome onto their son. Please see the diagram for more information about how XLHED is passed from parents to their children.
The gene for XLHED is passed from parents to children on the X chromosome.
What are the symptoms of XLHED?
Common symptoms include:
- A reduced ability to sweat. This is because babies born with XLHED have no, or fewer than normal, sweat glands or they don't sweat properly
- Missing and often pointed teeth (hypodontia)
- Sparse and slow-growing hair on both the head and body
- Drier than normal linings or membranes in the nose and mouth
- Breathing problems such as asthma
- Increased respiratory tract infections (colds, pneumonias, etc.)
- A discharge from the nose that smells bad
- Dry and scaly skin
Women who are carriers for XLHED may have none of the above symptoms, or they may have mild or even severe versions of them. The way each woman experiences symptoms of XLHED is unique.
What is it like to live with XLHED?
Because people with XLHED have a reduced ability to sweat, they are at risk for dangerously high body temperatures. Sweating is a way for the body to cool itself. People with XLHED may take these steps to keep cool:
- Wear cooling vests
- Spray themselves with water
- Drink cool fluids
- Avoid high temperatures
- Limit physical activity
Babies with XLHED have a greater risk of infections and other serious medical problems. Skin problems are another ongoing issue that can lead to painful infections like eczema. Also, children as young as 2 can have lifelong dental problems. Some children wear dentures as young as ages 2-3. Others undergo many difficult surgeries to receive dental implants. Dental problems like these can make it difficult for them to eat well and get enough nutrition from food.
Because of these differences, some children may experience teasing. They may feel uncomfortable in social situations and struggle with their self-esteem. It's important to be aware of this potential emotional effect of XLHED. Make sure you, or your family, have plenty of support. There are many XLHED advocacy groups around the world. They can help provide this type of support. We strongly urge you to get in touch with one or more of them today.
Are there any treatments available?
There are currently no specific treatments available for XLHED. However, doctors and patients have found ways to manage the challenges of living with XLHED. Edimer is developing EDI200 as a potential treatment that may improve the health and quality of life of future generations living with XLHED.
What is EDI200?
EDI200 is being developed as a potential treatment to replace the missing protein in newborn boys with XLHED. Studies have shown that use of EDI200 may lead to more normal development of hair, teeth, skin, and sweat glands.
A clinical trial of EDI200 for newborns affected by XLHED started in 2013. Edimer began enrolling participants in 2013 to study this possible treatment. EDI200 will only be available to newborns enrolled in this trial. If you are pregnant and may be an XLHED carrier, contact Edimer to learn more.
For all the latest medical news about XLHED and clinical studies, join the XLHED Network. Join now.