I got my genes tested this month, and what I found out puts a new face on my understanding of N24 and DSPD.
The first human genome was sequenced in 2003 and cost 2.7 billion dollars. Over the years researchers have improved their technique and reduced the cost dramatically. Recently Veritas Genetics announced it had reached the goal of the under $1000 genome, offering a full genome sequence to anyone for $999. Still very expensive but quite a drop from 2.7 billion!
Other companies also offer a more limited but still useful form of genomic testing. One of these is 23andMe which offers testing for $99-$199. Rather than plunging into the deep end of whole genome sequencing, I thought I’d go with 23andMe to confirm that I could get useful information with less expense. I am very impressed with what I was able to find out from 23andMe.
The method of 23andMe is based on analysis of what are called single nucleotide polymorphisms (SNPs). Most of the human genome is identical from person to person, which is why we are all humans and not horses or banana trees. SNP analysis focuses on variations in the genome of a particular common type.
The genetic code is a sequence of DNA nucleotides which we label with the letters A,T,G or C. So part of the code might read like this: …CTGAATGCAGT… An SNP refers to a situation where one letter of the code differs from person to person. So while one person may have the sequence CTGAATGCAGT another may have the sequence CTGAATTCAGT. Notice the only change is that the letter G in the 7th place has become a T. Typically one SNP will be more common in the population than the other. So, for example 90% of the population may have a G, which would be referred to as the major (more common) allele. The T would be called the minor allele. (Allele is another word for genetic letters.)
So if you sign up for 23andMe you send them a vial of your spit, and 4-6 weeks later they send you a link to their site where they give you information about a selection of your SNPs and what they mean, as well as some other genetic information.
Most of the information you get from 23andMe, at first glance, seems pretty basic. They tell you where your ancestors came from and a list of various genetic traits: is your hair likely to be curly, can you taste bitter foods etc. Interesting but hardly world-shaking in most cases.
But in addition to this pre-analyzed information 23andMe also allows you to download a file containing the raw data: a long list of the actual SNPs and your results. These you can upload to certain web sites such as Promethease for detailed analysis, or if you know what you are doing and what you are looking for you can look through the raw data yourself. That’s when the fun begins.
And I knew just what I wanted to look for.
In 2014 Daniel Kripke et al. published an article called, Circadian Polymorphisms in Night Owls, in Bipolars, and in Non-24-Hour Sleep Cycles. You can get the full text at the link below.
The study identified several SNPs statistically associated with N24 or DSPS. Not all of the SNPs studied by Kripke et al were tested by 23andMe but three of the most important ones were.
In the case of N24, Kripke et al. were particularly interested in variations in a gene called BHLHE40, or basic helix-loop-helix protein E 40. The protein produced by this gene plays a major role in the molecular clock.
The study found that subjects with N24 were statistically more likely to have one or two C alleles instead of a T at a portion of the genome labelled rs908078, which is part of the regulatory sequence for this gene. Looking at my 23andMe data I found this line:
rs908078 3 5024771 CT
So, yes indeed I did have one C allele. It might have been even more impressive if I had two, as some of the N24 subjects did, but one C is still interesting.
But I developed N24 as an adult, following chronotherapy. Before that I had DSPD. So if there is a genetic predisposition it might be even more likely to show up in genes associated with DSPD. Kripke et al found two such genes and corresponding SNPS.
The first is a gene called NFIL3 (nuclear factor, interleukin 3 regulated). It also plays a role in the circadian clock.
The SNP for NFIL3 is rs2482705, and people with DSPS are more likely to have two G alleles. So looking at my data file I find this line.
rs2482705 9 94182502 GG
So, yes, GG. I can cross out another letter on my bingo card.
The other gene is RORC (retinoic acid receptor-related orphan receptor C). This gene has many functions and is not well understood, but one of its roles is also in clock regulation.
The associated SNP is designated rs3828057. People with DSPS are more likely to have a GG allele. Going back to my data file I search for that string and find this.
rs3828057 1 151780177 CC
You might at first think that was a miss, but remember the structure of DNA. It consists of two strands linked together in a helix, which run in opposite directions, the sense strand and the antisense strand. A C in the sense strand matches a G in the antisense strand, and vice versa. An A matches to a T. So CC is actually equivalent to a GG in this case. It simply means one group tested the sense strand and the other the antisense strand.
So we have another hit.
So for the SNPs that were tested by 23andMe I am 3 for 3 in having the alleles associated with N24 or DSPD. I don’t want to make too much of this. These are statistical associations. It’s entirely possible to have either disorder and not have these genes or to have the genes and not the disorder. Nonetheless, while I am not yet ready to shout BINGO!, I find the presence of these genes intriguing. We aren’t quite ready to trace their function directly to the disorder but that may come in time. The first step in that process is to know what genes are involved. The fact that these genes are ones we do know are intimately involved in regulating the circadian clock is a good omen for our future understanding.
But there is also more on the horizon. Recall I mentioned 23andMe only tests a limited number of SNPs. Kripke et al reported a total of 9 SNPs associated with N24. While rs908078 was the one they focused on the most, the other 8 are also significant. But 23andMe only tested for rs980078. They did not test the other 8. But a whole genome sequencing, if I am ever able to afford that, should give results for the other 8. That’s a lot more letters to put on the bingo card!
I don’t think we are likely to explain N24 or DSPD entirely based on genetics. Developmental and epigenetic factors almost certainly play a role. But the more we know about the genetic aspects, the better off we will be. I must also add that genetic studies are not always replicated and it may turn out that all of this is a Will-o’-the-wisp that I will have to retract next year. But eventually real data will come out. As one of my favorite fictional characters said, “the truth is out there.”
LivingWithN24 (James Fadden)
This post also appears on the CSD-N web site. Please join CSD-N to help support research like this.
The WordPress.com stats helper monkeys prepared a 2015 annual report for this blog.
Here’s an excerpt:
The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 24,000 times in 2015. If it were a concert at Sydney Opera House, it would take about 9 sold-out performances for that many people to see it.
10 years ago my co-blogger Delayed2Sleep started this blog to bring awareness of Delayed Sleep Phase Syndrome. I joined as co-blogger 5 years ago under the name LivingWithN24. We both have continued to blog about issues affecting people with both DSPS and Non-24-Hour Sleep-Wake Cycle Disorder (N24).
I have been very gratified at the number of people online who have told us how this blog has helped them. For example several people have told me that the post on Charting the Course of N24 helped them make a sleep chart and get a diagnosis. Others have said that the Melatonin: Less is Sometimes More post has helped them find a dose that finally helps their sleep cycle.
Today is N24 Awareness Day. It is a day set aside by the online N24 community to help spread awareness of this condition. This is the third annual N24 Day.
In going online at the DSPS blog to write up something for today, I realized I had not posted anything here since last N24 Day. I had a twinge of guilt, but that soon went away. I may not have blogged much this year but I have done quite a lot this year concerning N24 and circadian disorders, some of it on my own and some as Vice-President of the Circadian Sleep Disorders Network.
I hope to blog here more in the future but in the meanwhile I thought I’d use this post to update the readers on what I have been doing in the world of N24 and circadian disorders generally. Some of the readers may already know about this, but many may not and for them I have a lot of useful links and information to share.
But first a word about N24 Awareness Day. The theme for this year is “Think Zebras!” This comes from a saying taught to doctors “When you hear hoof beats, think horses, not Zebras.” This means when faced with symptoms look for a common cause not a rare one. The patient with a cough, fever and muscle aches is more likely to have flu than Q fever.
But this approach leaves people with rare disorders out in the cold. Those of us with N24 truly are Zebras, and diagnosticians need to keep that in mind. I have said more about this in my post on the CSD-N site, so rather than repeat myself I will give you a link (and while you are there consider joining. It is a worthy cause.)
So what else has happened in the world of N24 since the last N24 Awareness Day? Well a few things…
I was honored this year to be asked to write an article on N24 for the journal Sleep Review. I should thank Ed Grandi for connecting us, and Sree Roy, the Editor of Sleep Review, for her hard work. The article is called “What You Need to Know about Non-24”. It is published online and in digital and paper formats.
I have been very gratified by the reception of the article by both patients and health professionals. A friend recently told me it turned up in the waiting room of her sleep clinic. So word is getting around about N24.
(This was my second formal article on N24. The first, which I don’t think I have linked to on this blog, is a report on N24 for the National Organization of Rare Disorders, which I co-authored with Dr. Katherine Sharkey a couple of years ago: http://rarediseases.org/rare-diseases/non-24-hour-sleep-wake-disorder/)
Another high point of the year was participating in an online course offered by Coursera called Circadian Clocks – How Rhythms Structure Life. It was taught by two eminent circadian researchers, Martha Merrow and Til Roenneberg of Ludwig-Maximilians-Universität München. I am not sure if the course will be offered again, but if you have a serious interest in circadian rhythms I highly recommend it.
Finally, another major event this year was the publication of new guidelines for the treatment of circadian disorders by the American Academy of Sleep Medicine.
A preliminary version of the guidelines was released earlier and interested parties were asked to comment. The deadline for comments was very tight. CSD-N submitted comments on the guidelines. In addition to helping compose the CSD-N comments I also submitted additional comments of my own which we did not have time to incorporate into the official CSD-N comments.
The most important aspect of the AASM guidelines — both their strength and weakness — is that they are based on a strict interpretation of the concept of evidence-based medicine. According to this approach only treatments which have been subjected to controlled clinical trials are given a recommendation. And clinical trials have to meet a number of strict criteria to be counted.
This is often a useful constraint. It avoids the recommendation of treatments which are ineffective. It is particularly useful in the case of common disorders where clinical trials can be organized. (To give an example from personal experience, I recently suffered a bout of diverticulitis. Antibiotics are often prescribed for this condition but at least 5 controlled trials have demonstrated that they make absolutely no difference in outcome.)
However, in the case of rare disorders such as N24, this restriction can be both a blessing and a curse. Given the rarity of sighted N24s there are very few clinical trials, and those that have been done did not meet the criteria of the AASM. Thus the guidelines give “no recommendation” for any treatment of sighted N24. For N24 in the blind, melatonin agonists are given a “weak for” recommendation.
The good side of this is it amply demonstrates the urgent need for more studies of treatments for N24, particularly in sighted patients. It is intolerable that there is no validated treatment for such a devastating disorder.
The bad side of this approach is that it discounts evidence such as case reports of the efficacy (albeit partial and with limitations) of treatments for sighted N24, in particular light/dark therapy or combinations of light/dark therapy with melatonin. In the absence of clinical trials for a rare disorder, case reports may be better than no evidence at all. Nevertheless it is true that in the absence of controlled trials we don’t know how effective such treatments are for sighted N24s as a whole. This is an issue I may discuss more in the future.
So that has been my past year of involvement with N24 awareness. In summary, there is more attention being paid to this condition. But we still have a long way to go. We need better understanding of the underlying biology of N24 — which is still poorly understood — and we need validated treatments.
— LivingWithN24 (James Fadden)
The WordPress.com stats helpers prepared a 2014 annual report for this blog about Circadian Rhythm Disorders (CRDs).
Here’s an excerpt:
The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 23,000 times in 2014. If it were a concert at Sydney Opera House, it would take about 9 sold-out performances for that many people to see it.
Tags: N24, N24 Awareness Day, Non-24, Tasimelteon
Well, it’s that time of year again. The nip of Autumn is in the air, and that can mean only one thing, N24 Awareness Day. Just one year ago, the N24 community celebrated the first N24 Day, having designated November 24th as our day to spread awareness of the condition.
2014 has certainly been an eventful year for awareness of N24. In January of this year the US Food and Drug Administration approved the first drug specifically designated for the treatment of N24 in totally blind patients. In the US, advertising of medicines is permitted and Vanda has been running advertisements on television and radio talking about N24. A year ago the average person had never heard of N24. Now, if you were to ask someone (at least in the US) if they had heard of N24 there is a good chance the answer would be yes, because of the Vanda campaign.
But awareness does not necessarily mean understanding. Unfortunately as awareness has spread, so have a number of myths and misconceptions about N24. People with N24 I have talked to tell me of the reactions that they now get which reflect these myths. It is worth addressing this issue.
Myth #1: “N24 only happens to blind persons”.
Vanda’s Non-24 campaign has particularly talked about blind persons since that is the population for which the drug is approved. It is true that if you are blind your chance of having N24 increases dramatically. Over 50% of totally blind persons will have N24. It is a serious condition — many blind persons have even said it is the worst part about being blind.
But N24 also occurs in sighted persons. I am sighted myself, and so are many other people with N24 that I know. There are many research articles on the condition and it is agreed that it does occur in individuals who have sight.
In the case of blind persons, the cause of N24 is the absence of light as a zeitgeber to regulate the circadian clock. This is not usually the issue with sighted persons. In sighted N24 the cause is a more complex dis-regulation of the body’s circadian system and sleep wake cycle. Although blind and sighted N24 share the same diagnostic name, the biology is quite different.
The rate of occurrence of N24 among sighted persons is much smaller than among the blind, but there are also many more sighted people overall. We don’t really have a good estimate of the total number of sighted N24s. We can put a lower bound. There are about 100 case reports in the medical literature. And online support groups number in the low hundreds. This is still a small percent of the population, but sighted N24 does exist.
Myth #2: “N24 is a disease invented by drug companies”
It is understandable that the average person, never having heard of this somewhat exotic condition, and suddenly deluged with paid advertising might think this condition was concocted for profit. One person with N24 told me her social services worker said, “Oh, N24, that’s that disease that no one really has.”
Nothing could be farther from the truth. Anyone who thinks that is the case needs to talk to the many persons who have suffered for years with this awful condition.
In my own case, I first developed N24 in 1982. I doubt I was influenced by a drug ad 30 years in the future. I was first diagnosed in 1992 at the National Institutes of Health. They didn’t just take my word for it. They conducted a 2 year study, with round-the-clock monitoring of blood chemicals via an IV line and a slew of other medical tests. This is a real condition due to a disorder of the biological clock and the regulation of the sleep-wake cycle.
There are many others who have endured this condition. You can read some personal accounts at the CSD-N web site under “personal stories”.
Bottom line: N24 is real and the suffering it causes is real.
Myth #3: “You can just take a pill and fix your N24”.
Again, this is an understandable reaction to a drug company campaign. But the reality is more complicated.
Let’s first deal with blind persons, the target population for the new drug Hetlioz. The most straightforward way to measure response to an N24 treatment is the percent who achieve entrainment. Entrainment does not mean everything is fixed, you can still have major symptoms such as debilitating exhaustion, but lack of entrainment does really mean treatment has not worked.
In the case of Hetlioz about 20% of patients achieved entrainment after 1 month of treatment. After 7 months this rose to to 59% although that figure does not include those who dropped out of the trial or whose period was not measured at 7 months. When all subjects are included, the percent of those who started the trial and achieved both entrainment and reduced symptoms at 1 or 7 months was only 28.9% (1). So success is by no means guaranteed and treatment can take a long time to achieve results.
This isn’t meant to single out Hetlioz for criticism. It may be a useful drug for some and I am glad it is available. Melatonin is also effective in many cases of blind N24. But neither is anything close to 100% successful for blind patients. The point is not that Hetlioz is an ineffective drug, because it does help a percentage of sufferers. The point is that N24 is hard to treat.
We don’t yet have data on Hetlioz in sighted N24s. The biology of sighted N24 suggests that melatonin and melatonin agonists such as Hetlioz may be of less use than in blind subjects. The prolonged intrinsic period of some N24s may be outside the range of entrainment by melatonin-like drugs. In practice, while some sighted N24s respond to melatonin and related drugs, most do not (2). Whether this will be any different with Hetlioz remains to be seen.
Of course sighted N24s have some treatment options not available to totally blind persons, namely light and dark therapy. These treatments can be successful in some cases, but not all. And the light/dark regimens are complicated and time consuming. Nor does this approach correct the underlying cause of the disorder. It is a symptomatic, not a curative treatment. Even when light entrainment works patients may be left with substantial residual symptoms such as tiredness or a split sleep schedule. I am known for strongly encouraging people to try light/dark treatment, but it is not a panacea.
All of this is a far cry from popping a pill to fix the disorder.
Those are three of the myths I have heard circulating in the past year. It has changed my perspective on how to approach N24 in discussions with medical professionals and the public. In the past when I told them I had N24 (or hypernycthemeral syndrome as it used to be called) I was greeted with a blank stare or “what is that?…can you spell it?” The reaction might be skeptical. On the other hand I was dealing with a blank slate and could tell them about the condition if they were willing to listen.
Now the situation for those of us with N24 is different. The good news is, people now may have heard of the condition. The bad news is, what they think they know about the disorder may not be the truth. In the words of Mark Twain, “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so”
With this new awareness, are we better off or not? I’m not sure. What do you think?
–posted by LivingWithN24 (James Fadden)
This post also appears on the CSD-N web site where you can find out more about N24 and other circadian disorders.
1. Marlene Dressman PhD. Clinical Program Efficacy. Tasimelteon, as presented to the FDA Peripheral and Central Nervous System Drugs Advisory Committee November 14, 2013 Silver Spring, MD slides CE-79 and CE-81
2.Kamei Y, Hayakawa T, Urata J, Uchiyama M, Shibui K, Kim K, Kudo Y, Okawa M. Melatonin treatment for circadian rhythm sleep disorders. Psychiatry Clin Neurosci. 2000 Jun;54(3):381-2.