Multisystemic Smooth Muscle Dysfunction Syndrome (MSMDS) is an ultra-rare genetic disease difficult to recognize at first glance. Its symptoms appear in different organs and are often confused with more common diseases, delaying diagnosis.
Early diagnosis can save lives and change the course of the disease.
Important note: The information on this page is not a substitute for medical advice. Always discuss it with your healthcare team.
What makes MSMDS particularly challenging to diagnose is that its manifestations can appear at different moments in life and vary in severity. Some signs are present from birth, while others develop progressively over time.
For this reason, diagnosis depends not only on identifying individual symptoms, but on recognizing how they connect. When multiple findings affect organs that rely on smooth muscle function (such as blood vessels, lungs, digestive system, or bladder) MSMDS should be considered.
Early recognition of this pattern is essential to guide genetic testing, avoid unnecessary risks, and ensure appropriate medical care.
Certain combinations of signs should raise suspicion, especially when they appear early in life.
Early diagnosis of MSMDS may be facilitated when two or more of these features coincide:
If two or more of these signs are present, MSMDS should be considered and a genetic evaluation requested.
Due to its extreme rarity and the wide range of symptoms, MSMDS is often confused with other partial diagnoses. While some of these may be correct in the short term, they do not explain the entirety of the clinical picture or the connection between the complications that arise over time. Among the most common are:
These partial diagnoses not only increase families’ uncertainty but also delay referral to specialists familiar with MSMDS. Consequently, a lack of adequate information can put the lives of the patients at risk.
A critical example is surgical interventions or tests such as MRIs. In children with MSMDS, anesthesia or sedation with standard protocols can trigger serious complications, including strokes.
To minimize permanent damage, it is essential that medical teams understand the specifics of this disease before any procedure.
The most accurate way to confirm MSMDS is through genetic testing, usually performed on a simple saliva sample. These tests analyze genes involved in smooth muscle and connective tissue function like ACTA2 and MYH11.
Doctors and researchers recommend genetic testing when two or more key symptoms appear together, most commonly congenital mydriasis (fixed dilated pupils) and patent ductus arteriosus.
Before referral to a genetics specialist, clinicians may perform:
Because different mutations may lead to MSMDS, identifying the exact genetic variant is essential to guide monitoring and care.
If you suspect MSMDS, ask your doctor for a genetic evaluation.
The options vary depending on the hospital and the specific case, but the first step would be to schedule a series of appointments with neurology, cardiology, pulmonology, gastroenterology and any other necessary specialties. Each department will carry out specific tests to establish the basis of the patient’s clinical picture such as:
Depending on the patient’s symptoms, some of these tests may be unnecessary, while others will be required. Each case is unique as well as the management and medical care of each person affected with Multisystemic Smooth Muscle Dysfunction Syndrome.
The path to an accurate diagnosis is often long and complex. The main challenges:
As a result, many families experience a prolonged and difficult journey before receiving an accurate diagnosis.
Reaching a diagnosis of MSMDS is not just about naming the disease. It’s about preventing life‑changing risks that can escalate in a matter of hours.
An early diagnosis means more time, fewer complications, and access to the right care from the very beginning.
Because with MSMDS, the challenge isn’t only diagnosing.
It’s diagnosing in time.
At ACTA2 Alliance, we know that early diagnosis can change the entire future of a person with MSMDS. To make that possible, we focus on:
Early diagnosis saves lives. Every child identified before a major complication gains time, treatment options, and a better chance of avoiding irreversible outcomes.
1. Zhou YL, Zhang YY, Cheng BL, Xu D, Tang LF, Chen ZM. Multisystemic smooth muscle dysfunction syndrome in children: a case report and literature review. Chinese Journal of Pediatrics, 2017.
https://europepmc.org/article/med/28822439
2. Nadine McCrea, Heather J. Fullerton, and Vijeya Ganesan. Genetic and Environmental Associations With Pediatric Cerebral Arteriopathy: Insights Into Disease Mechanisms. Stroke, 2019
https://www.ahajournals.org/doi/10.1161/STROKEAHA.118.020479
3. Mc Glacken-Byrne, A.B., Prentice, D., Roshandel, D. et al. High-resolution iris and retinal imaging in multisystemic smooth muscle dysfunction syndrome due to a novel Asn117Lys substitution in ACTA2: a case report. BMC Ophthalmol, 2020.
https://bmcophthalmol.biomedcentral.com/articles/10.1186/s12886-020-01344-w#citeas
4. Interstitial Lung Disease in MSMDS: Developmental Smooth Muscle Dysfunction in the Lungs. Speaker: Dr. Bernard Kinane (MGH). Presented at the 2025 MSMDS Conference. https://www.youtube.com/watch?v=dVMH-glRu90&list=PL9i5mdmWtAp4VhC76CV1OJ2WJNtnNXME7&index=15
5. Nicholas Houska, Michal Schafer, Kathryn C. Chatfield, Timothy J. Bernard, Richard J. Ing. Anesthetic Considerations for Children With Multisystem Smooth Muscle Dysfunction Syndrome and Review of the Literature, Journal of Cardiothoracic and Vascular Anesthesia, 2022. https://www.sciencedirect.com/science/article/abs/pii/S1053077022002786
6. Chen SN, Wang YQ, Hao CL, Lu YH, Jiang WJ, Gao CY, Wu M.Multisystem smooth muscle dysfunction syndrome in a Chinese girl: A case report and review of the literature. World J Clin Cases, 2019. https://www.wjgnet.com/2307-8960/full/v7/i24/4355.htm
7. Latest clinical recommendations on MSMDS imaging, Dr. Diana Tambala, MD (MGH). Presented at the 2025 MSMDS Conference. 2025.
https://youtu.be/Gz-sHg-kFRQ?si=gJGK9KUb_Wv5H306&t=1851
8. Petrov I, Keltchev A, Stankov Z, Vasilev S.The journey of a patient with ACTA2 mutation – literature review and case report.Cor Vasa 2022;64:619–621.https://e-coretvasa.cz/pdfs/cor/2022/06/08.pdf
*This content is not intended as a substitute for professional medical advice, diagnosis, or treatment. Should you require medical advice, please contact a qualified medical professional who is familiar with Multisystemic Smooth Muscle Dysfunction Syndrome.
© 2026 ACTA2 Alliance, All Rights Reserved.
