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Medicine

New Possible SIDS Genes Identified 88

Posted by ScuttleMonkey from the sudden-discoveries dept.
ScienceDaily is reporting that researchers at the Mayo Clinic have identified two more cardiac genes that could contribute to sudden infant death syndrome (SIDS). From the article: "In the two recent separate studies, researchers examined caveolin-3 (CAV3) and the cardiac ryanodine receptor (RyR2) and found molecular and functional evidence in both to implicate them as SIDS-susceptibility genes. Researchers examined the tissue of 135 unrelated cases of SIDS -- in infants with an average age of 3 months old -- that had been referred to Mayo Clinic's Sudden Death Genomics Laboratory for molecular autopsy. In each study, two of the 135 cases possessed mutations in either CAV3 or RyR2."
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New Possible SIDS Genes Identified More

New Possible SIDS Genes Identified

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  • Seems an odd gene to still exist (Score:5, Insightful)

    by AuMatar ( 183847 ) on Sunday May 21, 2006 @05:12AM (#15375084)
    Unless it has major advantages in youth/adult life. It increases the chance of death long before sexual maturity, evolution usually weeds those genes out rather quickly. Does the gene have any other known effect?

    • Re:Seems an odd gene to still exist (Score:5, Insightful)

      by Autumnmist ( 80543 ) on Sunday May 21, 2006 @05:29AM (#15375125)
      RTFA.

      The CAV3 and RYR2 genes are not the problems themselves. The problems come from specific MUTATIONS in those genes. The article specifically says: "In each study, two of the 135 cases possessed mutations in either CAV3 or RyR2."

      And before anyone starts going "2/135 isn't much," the scientists didn't say these mutations alone are responsible for the disease. They say In the two recent separate studies, researchers examined caveolin-3 (CAV3) and the cardiac ryanodine receptor (RyR2) and found molecular and functional evidence in both to implicate them as SIDS-susceptibility genes. . Susceptibility is the key word here. Having the mutations doesn't guarantee SIDS; it only increases the likelihood of it.

      Whenever you read a simplified article about genetic susceptibility, 9/10 times the "gene" that is linked to the disease doesn't actually mean the gene causes the disease. It means that mutations in the gene cause the disease.

      The mutations impair the normal function of the gene. In the case of these two genes, CAV3 [nih.gov] is the gene coding for a protein found in muscle and losing it results in muscle degeneration, while RYR2 [nih.gov] is the gene coding for a calcium-release receptor in cardiac muscle.

    • > It increases the chance of death long before sexual maturity, evolution usually
      > weeds those genes out rather quickly.

      It doesn't need to have an advantage to survive - it just has to not cause enough problems that it doesn't propogate at all. If the conditions required occur only rarely then it could stick around for a very long time.
    • evolution usually weeds those genes out rather quickly


      Only if their effects are significant. Perhaps SIDS was statistically irrelevant until other causes of death in children, such as infectious diseases, were attenuated by medicine and sanitation.

    • Recessive genes survive (Score:4, Informative)

      by MarkByers ( 770551 ) on Sunday May 21, 2006 @06:55AM (#15375262) Homepage Journal
      Recessive genes [wikipedia.org] survive because you can carry the gene and suffer no side-effects. You will pass it on to half of your children (on average), who will like you, become carriers but show no symptoms. If each carrier has an average 2 children, you can expect that the number of carriers will stay roughly constant from one generation to the next.

      For a child to show symptoms, both of their parents must be carriers of the recessive gene, and even then there is only a one-in-four chance of a child receiving two copies of the gene in question.

      Fatal genetic diseases can survive in the gene pool indefinitely if the gene that causes it is recessive.
      • Fatal genetic diseases can survive in the gene pool indefinitely if the gene that causes it is recessive. - not indefinitely but only until a point in time when the species learns to screen and prevent unwanted gene combinations in the offspring.
      • Harmful recessive allele frequencies do slowly decay over time. There are some harmful recessive genes that have positive effects in a heterozygous subject. These alleles are found in higher frequencies in populations where the positive effect is most beneficial. For example, being homozygous for sickle cell anemia decreases the likelihood of dying from malaria.
      • One reason potentially dangerous recessive genes hang around is because the carrier gains some secondary benefit from having it in the recessive form. The classic example is cicle cell (the blood cell deformity that can lead to cicle cell anemia). Carriers (even recessive carriers) gain the benefit of increased protection against malaria; of course, two recessive individuals have a 25% chance of having a cicle cell anemic child, but from an evolutionary perspective it is still a good thing.
      • As other people pointed out in other replies (but not explicitly): all genes drift, and all drifting is bad because it's altering the function of a gene that currently works. Sometimes the drift has new effects that outweigh the cost of losing an existing gene and that's when mutation is good. But in many cases, having two copies of a mutant gene will be fatal, but in select environments having NO copies of that gene will also increase mortality; having one copy is the best situation. Also, it turns out

    • It increases the chance of death long before sexual maturity, evolution usually weeds those genes out rather quickly.

      Well, there's only 2500 SIDS deaths each year in the US. That's about 1 per 1700 births. SIDS gets a lot of press because it's scary, unexplained, and unexpected, not because it's a serious threat. If mutations in these genes represent 10% of SIDS deaths, that's 1 per 17,000 births. I'd say that's fairly well stomped out as a genetic mutation.
    • Unless it has major advantages in youth/adult life.

      Actually, the adult form of the disease, the Adult Infant Death Syndrome (AIDS) is much worse. Those who do survive have a very difficult life ahead of them.

  • Color me skeptical, but... (Score:4, Insightful)

    by WoodstockJeff ( 568111 ) on Sunday May 21, 2006 @05:12AM (#15375086) Homepage
    Something that occurs in less than 2% of studied cases is a "potential contributing cause"?
    • Just about every study revelas something that **could** lead to some breakthough. Every Mars voyage "could explain where the world or the solar system came from". Every new concoction "could cure cancer". All this over-hyped reporting is getting very boring. And for all those people who's lives are potentially improved, well 99% of them get to be disappointed by unfulfilled hype.
    • Taking statistics (well, learning it on my own in preparation for the AP test) made me realize that yes, this is quite possible. A claim like "potential contributing cause" is probably based on a chi-square. The most obvious explanation I can think of is that it would be expected to occur in 0.001 % (or something) of cases if there were no link.
    • you have to ask yourself, how many were caused by environmental factors such as bedding and parents.

    • Re:Color me skeptical, but... (Score:5, Informative)

      by Idarubicin ( 579475 ) on Sunday May 21, 2006 @11:23AM (#15375937) Journal
      Something that occurs in less than 2% of studied cases is a "potential contributing cause"?

      Yep. It's not that unusual, actually. Physicians and epidemiologists start out with a number of dead people. They look for commonalities: symptoms, age at onset, unusual blood chemistry, etc. If they don't know what the root cause of an ailment is but they see similar patterns across a number of deaths, they coin a name for it. Here, it's Sudden Infant Death Syndrome--SIDS.

      The name tells you what happens but doesn't explain why. Saying "I have a runny nose and I've been sneezing a lot" would let me put you in the Sudden Adult Sniffling Syndrome (SASS) group, but it doesn't actually tell me what caused your ailment. It turns out that SASS actually has a number of different causes that ultimately lead to the same outcome. You may be having an allergic reaction to pollen. You might have a rhinovirus infection. Maybe you have a brain tumour. For this particular symptom, we have a lot of ways of evaluating the course of the disease and the status of the patient.

      With SIDS it is much more difficult. There may be many factors that make an individual susceptible, some genetic, some environmental, some a combination, some requiring a lot of bad luck.

      A comparison might be drawn with ALS (amyotrophic lateral sclerosis, known in the U.S. as Lou Gehrig's disease). In ALS, the motor neurons die off slowly, over the course of months or years. It starts in the periphery of the body and works its way up to the brain. Under the 'umbrella' of ALS, about 10% of cases are classified as 'familial'--that is, a patient is related to other individuals with the disease. Within this category, about 20% of cases are linked to one of several mutations in the gene SOD1 (superoxide dismutase). (One would expect most of the other familial cases to be related to other genes or gene combinations.) So while only about 2% of ALS cases are linked to SOD1 mutations, it is without a doubt a "contributing cause".

      • So while only about 2% of ALS cases are linked to SOD1 mutations, it is without a doubt a "contributing cause". Unless you can show that the gene SOD1 occurs in significantly less than 2% of the general population, you haven't proved anything. I could easily show that 2% of everyone who dies of heart disease has green eyes, but that doesn't prove a causal link. This sounds like medical researchers fishing for more funding. But then again, IANADWRTKOS (I Am Not A Dude Who Researches This Kind Of Stuff).
        • Unless you can show that the gene SOD1 occurs in significantly less than 2% of the general population, you haven't proved anything. I could easily show that 2% of everyone who dies of heart disease has green eyes, but that doesn't prove a causal link. This sounds like medical researchers fishing for more funding. But then again, IANADWRTKOS (I Am Not A Dude Who Researches This Kind Of Stuff).

          *sigh* No, I'm not just talking out of my ass. Yes, I do know what I'm talking about.

          SOD1 exists in all of the p

          • This still is not what the headline implies. This gene is not the cause of SIDS because 98% of babies who die of it don't have it. It is just one of many risk factors. If every child were screened for this mutation at or before birth, and could somehow be saved, you would still only be preventing 2% of SIDS deaths. Therefore, it's hardly worth persuing from a practical standpoint, although it may be worthwile from an academic standpoint. That was my point.

  • Possibilities.. (Score:4, Funny)

    by aero2600-5 ( 797736 ) on Sunday May 21, 2006 @05:13AM (#15375087)
    Have they tried researching culling songs yet?

    Aero

  • Lots of work to do... (Score:5, Insightful)

    by MarkByers ( 770551 ) on Sunday May 21, 2006 @05:18AM (#15375098) Homepage Journal
    In each study, two of the 135 cases possessed mutations in either CAV3 or RyR2.

    So one case of each mutation was found in each trial, and 266 of the 270 cases remain unsolved. It sounds like it is barely above a statistical anomaly.

    If you take a random sample of 270 people that like fishing, there will be some mutation that is common between two or more of them, but that's hardly enough to claim that this mutation makes you enjoy fishing.

    It looks like there is still a lot more research to do before we understand what the effects of different genes / mutations are.

    • Re:Lots of work to do... (Score:5, Informative)

      by Idarubicin ( 579475 ) on Sunday May 21, 2006 @11:42AM (#15376002) Journal
      If you take a random sample of 270 people that like fishing, there will be some mutation that is common between two or more of them, but that's hardly enough to claim that this mutation makes you enjoy fishing.

      You're assuming a 'fishing expedition' for any random gene mutation in common, though.

      These studies looked specifically at genes that were known to be related to heart problems in adults. CAV3 was recently identified as a genetic cause of long QT syndrome, while RyR2 is linked to catecholaminergic polymorphic ventricular tachycardia (press release [mayoclinic.org]).

      If these mutations occur at a low baseline rate in the general population, two hits of each may be quite significant. This link [mayoclinic...edings.com] indicates that RyR2 mutations are rare in the general population, with a probable incidence of under 1%. (They found no mutations in 200 healthy volunteers having 400 copies of the gene.) I'm not going to dig further for incidence numbers, but I'd bet good money that both RyR2 and CAV3 mutations are rare and that getting two hits of each in a population of 135 is quite unlikely.

      • In a group of 23 people, what are the odds that two of them have the same birthday? The answer may surprise you.
        • In a group of 23 people, what are the odds that two of them have the same birthday? The answer may surprise you.

          It's a shade better than 50%, if I remember correctly.

          Now here's a question for you: In a group of 135 people, what are the odds that two of them carry a mutation in the same gene related to cardiac function?

          Bonus question: Was your question or my question more closely related to the issue at hand?

  • Good philosophy (Score:5, Interesting)

    by goldaryn ( 834427 ) on Sunday May 21, 2006 @05:37AM (#15375138) Homepage
    Seems like a cool organisation. Wikipedia:
    "Mayo Clinic is significant in the way the medical physicians' are paid. In most health care systems, medical doctors are paid based on the number of patients that they see. The more patients seen, the more a doctor gets paid. At Mayo Clinic, medical doctors are paid a salary that is unaffected by patient volume. This allows the doctors to spend time with their patients and not worry so much about time constraints. Physicians and surgeons have no undue influence upon them to do more procedures and operations."

    That's a marvellous philosophy if you ask me, and they still made US$5.6 billion in 2004. Good for them.
    • Sure, it's a great philosophy if you can manage to get seen there. On the other hand, if that actually leads to an increase in time spent per patient for each doctor, than the throughput of the hospital is much less. Which means if this were instituted across the country...some people would get great care, but many just wouldn't get the opportunity to see a doctor at all. There's a shortage of doctors (or perhaps an abundance of patients) as it is!

  • That's fine and all... (Score:3, Funny)

    by Valar ( 167606 ) on Sunday May 21, 2006 @08:50AM (#15375476)
    but as a bachelor, I feel that we, as a society, should be confronting an altogether different problem-- SIBS, or Sudden Infant Birth Syndrome. ...

    Then again, it seems like most people here are doing their part for the cause.

  • From TFA: SIDS -- the sudden, unexplained death of an infant under 1 year old -- is estimated to cause 2,500 infant deaths each year.

    Guessed this was referring to the US only but I had to check. CDC page http://www.cdc.gov/SIDS/index.htm [cdc.gov] states: "Each year in the United States, more than 4,500 infants die suddenly of no obvious cause. Half of these sudden, unexplained infant deaths (SUID) are due to sudden infant death syndrome (SIDS)

    For the UK, I found this BBC article http://news.bbc.co.uk/2/hi/heal [bbc.co.uk]

  • What if there's no genetic anomoly? (Score:4, Interesting)

    by PIPBoy3000 ( 619296 ) on Sunday May 21, 2006 @09:49AM (#15375636)
    From what I understand, SIDS is caused when the brain doesn't properly send the "I'm not getting enough oxygen" message or the baby's unable to do anything about the message being sent. For example, sleeping on the front with fluffy blankets can make it hard for them to move around, even if they get the appropriate signal. In other cases, it may be that the signal itself may not get sent, as that part of the brain isn't developed enough. Things like pacifiers seem to help, perhaps because it maintains a level of awakeness or simply keeps their mouth open.

    It may be that the search for a root genetic cause may be futile. The good news is that simple physical precautions such as sleeping on the back and pacifiers seem to cut down on SIDS dramatically.

    Even if genetics play a role, it may be different than people think. It's important to realize that evolution often shoots for the "good enough" solution and that we carry around the baggage of billions of years of effort. Perhaps the babies that survived best historically were those who spent their limited growth "energy" on developing skeletal and muscle tissue. The part of the brain that signals low oxygen wasn't very useful during the first few months, as children typically slept in the arms of an adult. Speculation, of course, but it hopefully shows the ways that evolutionary pressures can lead to odd results.
    • The breathing impulse is driven by an excess of carbon dioxide, not a shortage of oxygen. It doesn't change the conclusion, but the distinction is interesting.
    • The good news is that simple physical precautions such as sleeping on the back and pacifiers seem to cut down on SIDS dramatically.

      Add to that keeping a window in a baby's room always opened. SIDS is nearly unheard of in countries which sleep with open windows all year round regardless of the weather. Compared to a kid's life the few pennies on the heating bill saved by "fart heating" are simply not worth it.

    • You're right that "children typically slept in the arms of an adult". We evolved to be this way, which is no good for people who want to sell cribs and cots and such.

      Sleeping with the adult is safest, provided that:

      a. the adult is not drunk (sleeping pills count)
      b. the adult is not obese
      c. the bedding is not insanely fluffy or a waterbed
      d. the adult does not smoke in bed

      (and if any of those risk factors are true, FIX THEM)

      • Not true.
        Sleeping with adults is always associated with a higher risk of SIDS.
        The above risk factors dramatically increase that risk.
        I'm a parent and a pathologist and in the last 6 months have done 2 post mortem examinations of infants who died while sleeping with their parents. The literature is also clear on this point. Infants who are sleeping with larger individuals (parents and siblings) are at higher risk.
        Prehistorically this would not have been the case as sleeping with parents would have given prot
        • It seems your literature is no good. It is critical to distinguish sleeping with a parent from sleeping with a sibling.

          Adults have very different sleep patterns from kids. A kid will easily roll onto a baby. A healthy adult will not do so.

          That said, it isn't a cure-all. Some babies are just meant to die.
          • The key to my point was in primitive societies and the high infant mortalities they experience the sleeping with parents can only be a good thing. The risk of a few accidental smotherings is far outweighed by the benefits. This is why our instincts tell us to do this.

            However in 1st world 21st century societies most causes of infant mortality have been eliminated. Sleeping with parents is no longer a benefit.
            We continue to argue this beceause our instincts scream at us telling us that sleeping with our infan
            • Even if that were true, there's more than just SIDS.

              Babies have more than just physical needs. It's good to have kids grow up to be appropriately confident and properly adjusted regarding love and caring.

              There's also the issue of brestfeeding, which is more likely to work if the baby is right next to the mom.
      • Sleeping with the adult is safest

        That's simply untrue. And your statement that we "evolved this way" is completely invalid unless you also change the rest of the environment to be similar to the majority of human evolution. Namely, outdoors, on the ground, with only minor bedding (straw/needles/etc), and with potential predators nearby. Oh, and in a small tribal village or communal setting.

        We don't live that way anymore and most of the risk factors that necessitated an infant to be sleeping with an adult ha
  • Here's a link discussing what Australia found. I tried to find a news article, but couldn't immediately

    http://www.mercola.com/2000/nov/5/victory_over_sid s.htm [mercola.com]
  • Am I the only one who read that "New Possible SSID Genes Identified"?

    So leaving your router with ssid linksys is hereditary? Who'd a thunk? :-P
  • As evidenced by the fact that many SIDs cases happen within a day(s) of being vaccinated, but the cause of death is labeled as SIDs. -- Usurper_ii

    -=-=-=-=-=-=

    More info:

    The vast majority of infant deaths caused by vaccinations are put into the vague category of SIDS (Sudden Infant Death Syndrome), also known as "crib death." Officially, SIDS is the second-leading cause of infant deaths in the United States, with between 8,000 and 10,500 deaths annually placed in this category. Some medical studies have estim
    • There is considerable evidence that vaccines prevent far more deaths than they cause. Diphtheria, pertussis, and tetanus are almost nonexistent in the U.S. while there are millions of deaths worldwide in countries that do not vaccinate their general population. Anyone who trusts the 'facts' you put in your post should look at this site [skeptics.com.au].

      What's wrong with you. These lies you're telling will get people killed.
      • Oh yes, you outed me. I did manage to sneak into the University of Nevada School of Medicine, the office of the publication Neurology, the University of California-Los Angeles (UCLA) and even the office of the FDA...planting fake facts for all of them to unknowingly publish! A person sure doesn't put much over on those /.ers.

        Usurper_ii
  • I'm going to offer an educated opinion about SIDS in general.

    Parent: Why did my infant suddenly die?
    Doctor1: I don't know.
    Doctor2: He died of, umm, Sudden Infant Death Syndrome.

    I think doctor2 is pretending to say something helpful, but really, does tacking syndrome on the end of the problem do us any good?
     
  • What happens if your R2D2 gene mutates?

    • The result is that the infant is no longer able to project hologram movies. The head still spins, though, so most people won't notice at a distance. The trouble often begins in school, when kids compare their projectors during recess. This leaves the child with a mutation in a very awkward social situation, and, without extensive parental and teacher support, the child can develop low self esteem over time. It is also well documented that children with this mutation almost never work at a movie theatre
  • It sounds like pure science fiction technobabble, and yet everyone's taking for granted, with no need for comment, that we're routinely doing "molecular autopsies". The forward-thinking people who landed us on the moon might have guessed that we might maybe know how to do a "molecular autopsy" within the next couple of centuries. But they wouldn't really have believed the idea has any place except between paperback covers.
  • Interesting that hindsight can be 20/20...

    slash image word "immune"

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