Do you struggle to stay awake throughout the day? And an afternoon nap (or two!) is essential for you to function?
You may be affected by a sleeping disorder known as narcolepsy.
What is narcolepsy?
Narcolepsy is a neurological disorder characterized by extreme daytime sleepiness and uncontrollable episodes of falling asleep during the day. This excessive daytime sleepiness should not be mistaken for the afternoon slump, since neurological defects are responsible for narcolepsy, rather than just sleep deprivation or lack of caffeine!
Who is at risk of narcolepsy?
Family members of an affected individual have a 20X – 40X increased risk of developing narcolepsy, indicating a strong genetic basis for the disorder. The genetic variant most closely associated with this sleeping disorder is HLA-DQB1*06:02. Individuals with this variant have a 7X to 25X increased risk of developing narcolepsy, although one recent European study indicates a much higher odds ratio of approximately 250-fold! Multiple other HLA-DQB1 variants also exist, and many of these provide some protection from narcolepsy, complicating the risk analyses.
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 of developing narcolepsy, 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.
Four Easy Steps
Step 1: Order test kit online
Step 2: Collect DNA sample using a simple and painless mouth swab
Step 3: Mail samples to the lab in the provided return envelope
Step 4: Receive your results online
|✓ Understand your genetic risk of narcolepsy|
|✓ Aid in an accurate diagnosis|
|✓ Painless buccal (mouth) swab sample collection|
|✓ All tests are run 2x for absolute accuracy|
|✓ Quickly collect samples in the privacy of your own home|
|✓ 24/7 online test status check|
|✓ Discreet online results option available|
|✓ No age limit|
|✓ State-of-the-art accredited testing laboratory|