What are the other Names for this Condition? (Also known as/Synonyms)

• Congenital Mydriasis, Patent Ductus Arteriosus, Thoracic Aortic Aneurysm, and Vasculopathy

What is Multisystemic Smooth Muscle Dysfunction Syndrome? (Definition/Background Information)

• Multisystemic Smooth Muscle Dysfunction Syndrome is a disease in which the activity of smooth muscle throughout the body is impaired
• This leads to widespread problems including blood vessel abnormalities, a decreased response of the pupils to light, a weak bladder, and weakened contractions of the muscles used for the digestion of food (hypoperistalsis).
• A certain mutation in the ACTA2 gene has been shown to cause this condition in some individuals

(Source: Multisystemic Smooth Muscle Dysfunction Syndrome; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

Who gets Multisystemic Smooth Muscle Dysfunction Syndrome? (Age and Sex Distribution)

• Multisystemic Smooth Muscle Dysfunction Syndrome is a rare congenital disorder. The presentation of symptoms may occur in infancy
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Multisystemic Smooth Muscle Dysfunction Syndrome? (Predisposing Factors)

• Currently, no risk factors have been clearly identified for Multisystemic Smooth Muscle Dysfunction Syndrome

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Multisystemic Smooth Muscle Dysfunction Syndrome? (Etiology)

• Multisystemic Smooth Muscle Dysfunction Syndrome may be caused by R179H mutation in the ACTA2 gene
• The mutation may occur sporadically, or be inherited in an autosomal dominant manner

Autosomal dominant inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Multisystemic Smooth Muscle Dysfunction Syndrome?

Symptoms for people with Multisystemic Smooth Muscle Dysfunction Syndrome can include the following:

• Congenital mydriasis (fixed dilated pupils)
• Patent Ductus Arteriosus
• Vascular problems including aneurysms
• Gastrintestinal problems
• Weak bladder
• Lung disease
• White matter abnormalities
• Changes consistent with MoyaMoya disease

The signs and symptoms of Multisystemic Smooth Muscle Dysfunction Syndrome may include:

• Cryptorchidism
• Dilatation of the cerebral artery
• Hyperperistalsis
• Intestinal malrotation
• Mydriasis
• Patent ductus arteriosus
• Periventricular white matter hyperdensities
• Retinal infarction
• Tachypnea
• Thoracic aortic aneurysm

(Source: Multisystemic Smooth Muscle Dysfunction Syndrome; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

How is Multisystemic Smooth Muscle Dysfunction Syndrome Diagnosed?

Multisystemic Smooth Muscle Dysfunction Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary
• Molecular genetic testing to check for or confirm the causative gene mutation

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Multisystemic Smooth Muscle Dysfunction Syndrome?

The complications of Multisystemic Smooth Muscle Dysfunction Syndrome may include:

• Malnutrition
• Rupture of aorta
• Pulmonary hypertension
• Macular edema
• Impact on quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Multisystemic Smooth Muscle Dysfunction Syndrome Treated?

There is no cure for Multisystemic Smooth Muscle Dysfunction Syndrome, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Multisystemic Smooth Muscle Dysfunction Syndrome be Prevented?

Multisystemic Smooth Muscle Dysfunction Syndrome may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Multisystemic Smooth Muscle Dysfunction Syndrome? (Outcomes/Resolutions)

• The prognosis of Multisystemic Smooth Muscle Dysfunction Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Multisystemic Smooth Muscle Dysfunction Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/