Does Race or Geography Affect Which MSA Subtype You Get?

Receiving a diagnosis of multiple system atrophy (MSA) can be incredibly overwhelming, and you may find yourself wondering why this happened or if certain people are more likely to get it. While MSA affects populations worldwide at roughly equal rates, the specific subtype a person develops is strongly linked to their geographic and genetic background ^[1]. People of Western descent (like North America and Europe) are much more likely to develop the parkinsonian subtype (MSA-P), whereas people of East Asian descent (particularly in Japan) are significantly more likely to develop the cerebellar subtype (MSA-C) ^[2].

How Subtypes Differ by Region

MSA is typically divided into two main subtypes based on which symptoms are most prominent when the disease begins. Both subtypes involve autonomic dysfunction (issues with automatic body processes like blood pressure and bladder control), but they differ in their primary movement symptoms ^[3].

• Western Populations and MSA-P: In North America and Europe, the parkinsonian subtype (MSA-P) is the most common form ^[2][4]. MSA-P is characterized primarily by symptoms similar to Parkinson’s disease, such as stiffness, slowed movements, and tremors. This occurs because the disease affects the striatonigral system, a brain network that helps control smooth, voluntary muscle movement ^[4]. If you have MSA-P, your daily management will likely focus heavily on maintaining mobility and managing muscle stiffness.
• Asian Populations and MSA-C: In East Asian populations, particularly in Japan and China, the cerebellar subtype (MSA-C) is significantly more prevalent ^[2]. MSA-C primarily causes ataxia, which includes problems with balance, coordination, and walking. This subtype involves changes in the olivopontocerebellar network, the part of the brain responsible for coordinating your balance and precise movements ^[4][5]. For those with MSA-C, physical therapy often focuses on fall prevention and coordination exercises.

Interestingly, recent data from Japan suggests that as the population ages and doctors get better at distinguishing MSA from Parkinson’s disease, the proportion of MSA-P diagnoses may be slightly larger than historically reported, though MSA-C remains the dominant subtype there ^[6].

Why Do Geography and Genetic Background Matter?

The distinct differences in how MSA presents across the globe are believed to be partly driven by genetics ^[2]. Researchers have found that certain genetic variations are more common in specific populations.

For example, variants in the COQ2 gene have been identified as a susceptibility factor for developing MSA ^[7]. These genetic variants are particularly associated with the MSA-C subtype and are found more frequently in East Asian populations than in Western populations ^[8][9]. This demonstrates that ethnic variation in genetic risk plays a role in determining which parts of the brain are most vulnerable to the disease.

However, it is crucial to understand that despite these genetic susceptibility factors, the vast majority of MSA cases are sporadic ^[10][11]. This means the disease occurs randomly and is not considered a condition that is directly passed down from parent to child.

Overall Global Incidence

While the subtypes of MSA are heavily influenced by a person’s ancestry and geographic origins, the overall likelihood of getting MSA is roughly equal around the world ^[1].

Sometimes, reported rates of MSA seem to vary from one country to another. However, experts believe this is mostly due to differences in how the disease is studied, diagnosed, and recorded rather than true differences in how often the disease occurs ^[1]. Diagnostic criteria, the average age of the population, and how healthcare systems track rare diseases all make direct country-to-country comparisons difficult ^[1].

Understanding your background can help your care team anticipate which symptoms might be most prominent. Regardless of where you live or what subtype you have, your care team will work with you to manage your specific symptoms and preserve your quality of life.