The Journey to an NPC Diagnosis

Diagnosis is a key step to moving forward

Niemann-Pick type C (NPC) is a rare disease, so it’s not always the first thing a doctor might consider. It also affects every person differently, with a wide range of symptoms that can overlap with more common conditions, sometimes leading to misdiagnosis.

Because NPC is a progressive disease, meaning it gets worse over time, an accurate diagnosis and early intervention are crucial. It allows you or your loved one to begin treatment sooner, which can lead to better outcomes. Modern genetic testing is helping people get answers more quickly than ever before.

While the journey can be complicated, it is manageable with the right tools and guidance. Your advocacy for yourself or your loved one is the most powerful tool you have, and understanding what goes into a diagnosis can help you feel more prepared and in control.

The foundation of diagnosis

The first step in the diagnostic journey is always a thorough clinical evaluation with a doctor, which includes:

• A detailed medical history: Be prepared to discuss when symptoms started, how long they’ve lasted, and how they’ve been progressing or changing over time. Every detail is a clue.
• A comprehensive physical exam: Your doctor will conduct a physical and neurological exam to look for key signs of NPC. This includes checking for an enlarged liver or spleen (what your doctor may call “visceral symptoms”) and looking for issues with eye movement, balance, or coordination (which they might refer to as “neurological symptoms”).

The role of specialists in diagnosis

Because the symptoms of NPC can appear so differently, your primary doctor may refer you to a specialist, such as a geneticist, neurologist, or metabolic specialist who has the expertise needed.

Learn more about who might be part of your care team here.

Uncovering clues with medical tests

Confirming an NPC diagnosis will require specific tests to look for biological evidence of NPC, including:

• Biomarker testing: This is a blood test to look for specific substances, known as biomarkers, that are typically elevated in people with NPC. One of the key biomarkers in NPC is a substance called an oxysterol.
• Genetic testing: This analyzes a blood sample to look for disease-causing mutations in the NPC1 or NPC2 genes. A positive result confirms the diagnosis.

Learn more about genetic testing here.

Older methods, like skin biopsies, were once common but have largely been replaced by these more accurate and less invasive modern tests, making the diagnostic process faster and more straightforward.

Understanding your results

A definitive diagnosis of NPC is typically made when a person has:

• Positive results from biomarker tests (eg, elevated oxysterols)
• AND a genetic test that identifies mutations in the NPC1 or NPC2 gene

If you or your loved one’s case is more complex, tests may need to be repeated or combined to provide a clear answer.

Though every person has their own NPC journey, you may find encouragement by watching others share their diagnosis experiences. Watch Amy’s family journey.