Snowflake disease is no laughing matter.

While the term “snowflake” has been used to mock a fragile person who melts easily, it’s also a nickname for a rare neuromuscular disease.

The condition causes the body to break down and become weak — and treatment is difficult as it becomes more complicated over the years.

Approximately 82,000 to 85,000 US adults were diagnosed with myasthenia gravis in 2024, but health experts note the numbers could be higher since the disease can be difficult to detect.

Last year, tennis legend and nine-time Grand Slam champ Monica Seles announced she was quietly battling the condition she’d never even heard of before her diagnosis.

One of her early symptoms was double vision, often the first sign, along with drooping eyelids, which affects more than half of patients.

Myasthenia gravis is an autoimmune condition that occurs when communication breaks down between nerves and muscles, causing the muscles to weaken and grow fatigued throughout the day.

Voluntary muscles that we control in the face, arms, legs or throat are often affected.

Muscle weakness in the arms, legs or neck can make everyday actions like carrying something, walking or even holding the head up difficult.

About 15% experience early symptoms that affect the face and throat muscles, resulting in slurred or soft speech, trouble chewing or swallowing, changing facial expressions or even difficulty breathing.

Some call it the “snowflake disease” because no two people experience the same symptoms — just like no two snowflakes are alike.

Symptoms can also come and go, potentially improving when the weak muscle is rested and worsening if the muscle is used.

Notably, the disease strikes very different demographic groups.

Older men over the age of 60 are often affected, while women with myasthenia gravis tend to be younger than 40 and more active.

Neurologists tailor treatments based on affected muscle groups and the patient’s health conditions, but there is no cure.

“It often becomes more severe over time,” Gianluca Pirozzi, head of development, regulatory and safety at Alexion, AstraZeneca Rare Disease, told Nature Portfolio. “Over the years, we’ve been researching ways to be able to address the underlying cause.”

Various medications may be used to manage symptoms, such as steroids (suited for short-term use) or cholinesterase inhibitors that boost the signal between nerves and muscles for better strength.

Surgical removal of the thymus gland, which is involved in immune system function, may also be an option.

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