DNA Narcolepsy Test
Fee Schedule for Year 2019
|Test Type||Testing Time||Fee|
|DNA Narcolepsy Test||2 to 4 weeks||RM2330Order Kit|
All orders received before 2pm are shipped out the same business day. All orders received after 2pm or on weekends or holidays are shipped out the following business day. 24/7 online status check and account management available for all tests.
What is narcolepsy?
Narcolepsy is a neurological condition 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 sleep deprivation.
Depending on how long we sleep, we go through four to six separate sleep cycles. Each cycle lasts about 100-110 minutes. There are two distinct phases to each cycle: (1) non-rapid eye movement (NREM) sleep and (2) rapid eye movement (REM) sleep.
We enter REM sleep about 70-90 minutes after falling asleep. During REM sleep, our brains becomes active. This is when we dream, and experience temporary muscle paralysis.
People with narcolepsy enter REM sleep just a few minutes after falling asleep. This explains the symptoms associated with narcolepsy – sleep paralysis, vivid hallucinations and collapsing into a sleep-like state while remaining conscious (called cataplexy).
How common is narcolepsy?
Narcolepsy affects between 1 in 2000 and 1 in 5000 people and only about 25% of affected people are actually correctly diagnosed. Often people are mistakenly diagnosed with psychiatric or emotional problems.
The main symptoms of narcolepsy include excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic or vivid hallucinations. Other symptoms of narcolepsy can include microsleep (temporary episodes of sleep that last only a few seconds), atonia (loss of muscle strength), periodic limb movement disorder (involuntary leg muscle contractions) and a rapid entry into REM sleep.
Genetics of narcolepsy
Although most narcolepsy cases are sporadic, there is still a strong genetic basis. The family members of an affected individual have a 20- to 40-fold increased risk of developing narcolepsy.
There is a strong association between narcolepsy and the human leukocyte antigen HLA-DQB1, as 90-99% of people (99% of Caucasians) affected with narcolepsy and cataplexy have the HLA-DQB1*06:02 allele.
Inheriting the HLA-DQB1*06:02 allele increases the risk of narcolepsy by 7- to 25-fold, depending on ethnicity. However, not everyone with this mutation will develop narcolepsy, as other factors such as infections, trauma, hormalal changes, stress or immune system problems are also involved.
DNA testing for narcolepsy
A simple DNA test can determine which allele of HLA-DQB1 an individual has inherited.
- Inheriting two copies of HLA-DBQ1*06:02 (homozygous) increases the risk of narcolepsy between 7- and 25-fold, compared to a person who does not carry the HLA-DQB1*06:02 allele. HLA-DQB1*06:02 homozygotes will pass the narcolepsy-associated allele onto all their children.
- HLA-DQB1*06:02 heterozygotes, who have one copy of the HLA-DQB1*06:02 allele and one copy of an alternative HLA-DQB1 allele, are also at an increased risk of narcolepsy, but not at the same magnitude as HLA-DQB1*06:02 homozygotes. HLA-DQB1*06:02 heterozygotes have a 50% chance of passing the narcolepsy-associated allele onto their children.
- If an individual does not carry the HLA-DQB1*06:02 allele, it is unlikely that they will suffer from narcolepsy, and they will not pass the narcolepsy-associated allele to the next generation.