Fragile
X syndrome is one of those genetic disorders we learn vaguely about in our Introductory Biology course during freshman year, but most people tend not to know the
specifics of what fragile X is and how it impacts those afflicted with the
disorder. In fact, fragile X syndrome is the most common inherited cause of
intellectual disability in males. Symptoms include intellectual disabilities,
problems with social interaction, delayed speech, hyperactivity, repetitive
behaviors and speech. Not to mention, about ten percent of those with fragile X
experience seizures and about one third meet the diagnostic criteria for autism
spectrum disorder. So clearly fragile X syndrome can have significant and
detrimental consequences to those inflicted with the genetic disorder. Yet
until now, not much was previously known about the physicalities underlying
fragile X.
This recently-published study that delves
into the neural signatures underlying fragile X syndrome was performed by
researchers at UNC School of Medicine. The researchers used MRI techniques to
image the brains of 100 infants, 27 of which were later diagnosed with fragile
X and 73 who did not develop the condition. This study focused on 19 white
matter fiber tracts in the brain (pictured below). Fiber tracts are bundles of
myelinated axons- the long parts of neurons that extend across the brain or
throughout the nervous system. Like bundles of cables, these bundles of axons
connect various parts of the brain so that neurons can rapidly communicate with
each other. Such communication is essential, especially for proper
neurodevelopment during infancy.
The imaging processes and analytical
analysis utilized in this study found significant differences in the
development of 12 of the 19 fiber tracts in babies with fragile X from as early
as six months. In general, the infants who ended up being diagnosed with
fragile X had significantly less-developed fiber tracts in various parts of the
brain compared to infants who were not later diagnosed with the condition. These
results corroborate the results found in previous research with rodents- that
the role of fragile X gene expression is essential in the early development of
white matter in infants.
So why are these results
significant? Co-senior author Heather C. Hazlett, Ph.D., explains that “one of the
exciting things about our findings is that the white matter differences we
observe could be used as an objective marker for treatment effectiveness.” That
is, white matter circuitry is a potentially promising and measurable target
for early intervention in the treatment of fragile X syndrome. Who knows, maybe
with further, more extensive research, we will one day be able to develop a
course of treatment that focuses on correcting this difference in the white
matter fiber tracts. Such a discovery could potentially lead to a significant
decrease in the number of individuals affected by the condition, as well as
potentially lessen the severity of the syndrome in some individuals.
Story
Inspiration:
University of
North Carolina Health Care. "Fragile X imaging study reveals differences
in infant brains." ScienceDaily. ScienceDaily, 4 April 2018.
.
Journal
Reference:
Meghan R.
Swanson et al. Development of White
Matter Circuitry in Infants With Fragile X Syndrome. JAMA Psychiatry, 2018
DOI: 10.1001/jamapsychiatry.2018.0180
- Posted by
Nicole Ayres (1)
Post #3
I'm very surprised to learn that Fragile X syndrome is the number one cause of inherited intellectual disabilities in males. I hope that more research goes into this syndrome and its treatment. I also wonder if there is any genetic pre-screening for this syndrome, and to what level are its biomarkers and genetic factors known.
ReplyDelete- Rund Tawfiq (3)
I was also very surprised by this fact considering I had not previously known much at all about fragile X syndrome! Neither the ScienceDaily article nor the paper mentioned much on genetic pre-screening, but I would imagine that it is detectable if you are looking for it, given it's effect on the structure of the X chromosome.
Delete-Nicole Ayres (1)
I have never heard of this genetic disorder. It's interesting how less fiber bundles leads to this. It must have something to do with neurons not being able to communicate as efficiently. Cool read!
ReplyDelete-- Hannah Kullberg (2)
I hadn't heard of it either so I was just as shocked! But yes, you're exactly right- fragile X syndrome is caused by mutations in the FMR1 gene on the X chromosome. This gene codes for a protein, called FMRP, which helps regulate the production of other proteins and plays a role in the development of synapses. So mutations in the FMR1 gene ultimately have detrimental consequences on synapse development and communication as a whole!
Delete-Nicole Ayres (1)
With how abundant it is i'm surprised to be hearing this information for the first time. Is it safe to assume that less communication in the brain is the sole cause of this condition? I also wonder if the reason if its so common since males have only one X chromosome and its an X linked condition.
ReplyDeletePosted by Sarah Kamukala
Agreed, I too was shocked there isn't more public awareness on the topic. I think it's tricky to say that less communication in the brain is the absolute sole cause of fragile X, but it's definitely a factor. And as for the gender differential in individuals affected, the rationale is also a little interesting. Fragile X follows an X-linked dominant inheritance pattern. Thus, it only takes females one copy of the altered gene to cause the condition (even though females have 2 X chromosomes). But it's also understood that males tend to experience more severe symptoms than females, however, I don't think it's entirely understood why this is.
Delete-Nicole Ayres (1)
Super interesting, never heard of this genetic disorder outside of it maybe being mentioned in a genetics class or two. Didnt remember much about it to be honest. Part of me wonders how many factors truly affect the disorder. As in is it purely inherited or can it become a late onset thing too.
ReplyDeleteLeon Mamish (2)