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!
How Common is Narcolepsy?
Between 1 in 2000 and 1 in 5000 people are affected by narcolepsy. However, only about 25% of the cases are correctly diagnosed, and often narcoleptics are mistakenly diagnosed with psychiatric or emotional problems. Family members of an affected individual also have a 20X – 40X increased risk of developing narcolepsy.
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 narcolepsy diagnosis.
Approximately 90-99% of people with narcolepsy carry a variant of the HLA-DQB1 gene known as the HLA-DQB1*06:02 allele.
- Two copies of HLA-DBQ1*06:02 = 7X – 25X increased risk of narcolepsy (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 of narcolepsy
However, 15 – 25% of the unaffected people, also carry the HLA-DQB1*06:02 variant, suggesting genetics is not the only factor that contributes to narcolepsy. Multiple other HLA-DQB1 variants also exist, and many of these provide some protection from narcolepsy, complicating the risk analyses.
How many diabetes risk factors do you have?
- 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