Myhre syndrome

What causes Myhre syndrome?

Myhre syndrome is caused by mutations in the SMAD4 gene. This gene gives the body instructions for making a protein involved in sending chemical signals from the surface of cells to the nucleus of cells. The nucleus contains most of the cell's genetic material. This specific signaling pathway allows the environment outside the cell to affect how the cell makes other proteins. The SMAD4 protein interacts with other proteins to control the activity of other genes that influence development both before and after birth.

Mutations in the SMAD4 gene that cause Myhre syndrome have been found to cause a "gain-of-function" of the SMAD4 protein, causing increased stability. This disrupts the signaling pathway, and ultimately the ability of signals to properly communicate how other genes should function. This results in abnormal development of the skeleton, cardiac muscle, and central nervous system, causing the symptoms of Myhre syndrome.

Last updated on 05-01-20

How is Myhre syndrome inherited?

Myhre syndrome is an autosomal dominant condition. This means that having a change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the condition. There is nothing that either parent can do, before or during a pregnancy, to cause a child to have this condition.

In all reported cases of Myhre syndrome to date, the mutation causing the condition has occurred for the first time in a person with no family history of Myhre syndrome. This is called a de novo mutation. De novo mutations are not inherited from a parent, but occur randomly.

When a person with a mutation that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that mutation. However, it has been reported that no person with Myhre syndrome has had children, although fertility in people with Myhre syndrome has not been studied.

Last updated on 05-01-20

What is Myhre syndrome?

Myhre syndrome is a rare, connective tissue disorder that affects many parts of the body. Signs and symptoms include fibrosis (thickening and scarring of connective tissue), intellectual disability, distinctive facial features, skeletal abnormalities, and/or various birth defects. The syndrome may affect the structure or function of the heart, the respiratory system, the gastrointestinal system, and the skin. Myhre syndrome is caused by a mutation in the SMAD4 gene. The mutation typically occurs for the first time in an affected person. To date, no reported cases have been inherited from a parent. Inheritance is autosomal dominant, but there are no reported cases of a person with Myhre syndrome having children. Treatment addresses each symptom present and may include limiting the risk of trauma to tissues, surgery for birth defects or complications, and routine management of learning delays or behavioral problems.

Last updated on 05-01-20

Is there anything we should be aware of for later in life?

Growth problems, abnormally stiff joints, and hearing impairment may not become obvious until late infancy or early childhood (and may continue on through adolescence). Periodic hearing tests are recommended. Muscle enlargement (generalized muscular hypertrophy) may also become more evident during childhood.

Last updated on 05-01-20

How might Myhre syndrome be treated?

Treatment of Myhre syndrome depends on each symptom present. Special attention should be paid to limiting trauma to tissues. Specialists that are involved in assessing or treating people with Myhre syndrome include cardiologists, orthopedists, respiratory specialists (lung doctors), gastroenterologists, and other healthcare professionals. Some abnormalities or complications may require surgery. Long-term follow up and regular clinical checkups are needed to recognize the onset of certain symptoms or complications.

Early intervention is important to ensure that children with Myhre syndrome reach their potential. Special services that may be helpful for children may include special remedial education, special social support, physical therapy, speech therapy, or other services.

Last updated on 05-01-20

Name: Little People of America, Inc. 617 Broadway #518
Sonoma, CA, 95476, United States
Phone: +1-714-368-3689 Toll Free: 1-888-572-2001 Fax : +1-707-721-1896 Email: Url:
Name: Myhre Syndrome Foundation 25 Creekwood Circle
Richardson, TX, 75080,
Phone: (202) 656-9473 Email: Url: Online contact form:
Myhre syndrome Genetics Home Reference. January 2013; Reference Link Myhre Syndrome National Organization for Rare Disorders (NORD). 2015; Reference Link

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