DNA Narcolepsy Test

What are the symptoms of narcolepsy?

This disorder is often incorrectly diagnosed because it involves a wide variety of neurological symptoms. The symptoms include:

• Excessive daytime sleepiness (100% of affected individuals)
• Cataplexy – a sudden loss of voluntary muscle tone (70% of affected individuals)
• Sleep paralysis and/or vivid hallucinations (10 to 20% of affected individuals)
• Microsleep (sleep episodes that only last a few seconds)
• Nighttime wakefulness
• Atonia (loss of muscle strength)
• Involuntary leg muscle contractions
• Rapid entry into REM sleep

How common is narcolepsy?

Between 1 in 2000 and 1 in 5000 people are thought to be affected by narcolepsy. However, only about 25% are correctly diagnosed, and often people are instead mistakenly diagnosed with psychiatric or emotional problems. Family members of an affected individual also have a 20X – 40X increased risk, indicating a strong genetic basis for the disorder.

The autoimmunity theory

About 70% of people with narcolepsy also suffer from cataplexy, which is caused by lower levels of a neurotransmitter named hypocretin (also called orexin). However, no genetic changes have been observed in the hypocretin gene. The neurons that produce hypocretin gradually die off in individuals with narcolepsy. Given the role of HLA-DQ proteins in immunity, it is believed that they play a role in this cell death; supporting the hypothesis that narcolepsy is an autoimmune disease. Celiac disease is another autoimmune disease that occurs due to changes in the HLA-DQ genes. The HLA-DQ changes in celiac disease cause an aberrant immune response and severe intestinal lining damage, triggered by the consumption of gluten. The trigger (if any) for narcolepsy is currently unknown, but a similar aberrant autoimmune response occurs, this time resulting in the destruction of healthy (and essential) hypocretin-producing neurons.

Genetics of narcolepsy

90-99% of individuals with narcolepsy carry a variant of the HLA-DQB1 gene known as the HLA-DQB1*06:02 allele. Approximately 15 – 25% of the unaffected worldwide population, also have HLA-DQB1*06:02, so other factors must also contribute to this disorder.

• Two copies of HLA-DBQ1*06:02 = 7X – 25X increased risk (or potentially up to 250X increased risk!)
• One copy of HLA-DBQ1*06:02 + an alternative HLA-DBQ1 allele = >3X increased risk (depending on the risk or protective affect of the alternative allele)
• Absence of HLA-DBQ1*06:02 = Low risk

This genetic analysis detects the HLA-DQB1*06:02 allele associated with narcolepsy. It is a useful tool, in conjunction with other clinical symptoms, for an accurate diagnosis.

Three Easy Steps

Step 1: Order test kit online

Step 2: Collect DNA sample using a painless mouth swab, and mail to the lab in the provided return envelope

Step 3: Receive your results online

Click here for more details and to watch our explanatory video.