an international and interdisciplinary journal of postmodern cultural sound, text and image
Volume 13, June -
October 2016, ISSN 1552-5112
Postmodern Autism, or the Call of the Orangutan: Meet 13q12
And the only dramatic event in this circular maze is the unexpected
about-face, (a distant reminder of Orpheus and Eurydice), which risks
shattering the fantastic illusion of a double life.
Jean Baudrillard,
Please Follow Me (1983)
Introduction: Meet 13q12
13q12
is a stretch of DNA on chromosome 13 in the human genome. Historically, its
linkage with autism was exceedingly rare. In an article from 2002, reporting an
observed sporadic case of autism involving 13q12, it was stated that only two
previous reports of autism associated with chromosome 13 were known.[1]
Subsequently, additional cases have been
identified in
SFARI
shows that where 13q12 is linked to autism, it is generally identified in terms
of a copy number variation (CNV) such as a chromosomal deletion, which is to
say part of the chromosome is missing; or alternatively, as a chromosomal
duplication, where the chromosome has two copies of a particular section of
DNA, where it most often only has one. Newman et al. report that CNV
duplications most often occur in tandem (some studies state the opposite; see
Marques-Bonet et al.), and that some create ‘fusion’
genes at breakpoints.[3]
Further, CNVs are now understood to play an important role in genetic
evolution; duplicated sequences in particular, may be responsible for large
scale genomic changes that offer the potentially selective advantage of new
gene creation, while at the same time presenting the liability of a high
mutation rate, which may lead to disease not limited to neuropsychiatric and
neurodevelopmental illness.[4]
We call observable individual characteristics ‘phenotypes’; and novel phenotypes may emerge under such scenarios. Much of genetic research is focused upon the discovery of the ‘genotype’, or genetic constitution, of already established clinical phenotypes, such as autism spectrum disorder (ASD), or breast cancer, for example.
Human Chromosome 13
The Scream of the
Butterfly: 13q12 Duplication
All naturally-occurring living things,
such as the family Hominidae (i.e. hominids, including the great apes), exist within a perpetual state of flux,
always in a state of evolution; even if much of the ‘change’ goes unnoticed or
undetected by humans. For example, Homo
neanderthalensis and Homo sapiens
have mated in the past, and evidence of past mating between the two species
reveals itself within Homo sapiens;
this startling fact, is a relatively recent observation. For example, its been discovered that heightened risk for nicotine
addiction, strokes and even depression, all appear to be have been inherited by
many Homo sapiens that share
Neanderthal ancestral history. In other words, humanity, in its most ‘modern’
sense, presents with the symptomatology of a surprisingly ambiguous ancient
admixture.[5] In another example, it has been
reported (and DNA studies confirm) that chimpanzees have mated with bonobos,
and that in the wild, genetic admixture “appears to have been widespread during
hominid evolution.”[6]
Thus, in many ways known but poorly understood (e.g. the variable genetic process of malaria adaptation that Homo sapiens appear to share with some primates,[7] and the MHC II genes that Homo sapiens share with some primates, etc.[8]), Hominidae genetic history is intertwined to an extent the ramifications of which remain remarkably unknown and unexplored. What we do know is that while we, the extant great apes, are each remarkably different species (i.e. the four genera including: Pongo (Orangutans), Gorilla (gorillas), Pan (chimpanzees and bonobos) and Homo (humans)), we share a sort of hybridized constitution, far more closely related than most human beings probably recognize and understand. And since we share such an intimately close ancestral genetic heritage, we also share observable characteristics. Some of these traits are ordinary and normalized (e.g. variable bipedalism), while other characteristics may be recognizable as a clinically diagnosed illness (e.g. ASD). It is a link to ASD that I wish to illustrate here.
The
Call of the Orangutan
What is a hominid? Scientifically, we
all share much of the same genome, with human/ape similarity reaching its total
peak at the human/chimpanzee nexus, which reaches a ~96% homology.
Philosophically, the difference among the great apes appears enormous, though
it is not my aim to discuss that topic here. In any event, when examining
differences among individual members of just one of the great apes, Homo sapiens for example, the
differences at the genotypic level may be tiny, while phenotypically-speaking
differences can be quite extraordinary, as we all have probably experienced
just how different human beings may be, relative to ourselves and others. And
when it comes to human illness, race, sexual orientation, etc., the variation
seems almost infinite. But it’s medical difference that we’re interested in
here, specifically with regard to autism, or ASD, as it is now so often called.
Many researchers of ASD, parents of
children with ASD, clinicians and even autistic patients advocate for
increasing the awareness of a concept called ‘neurodiversity’, where ASD is
understood as a unique feature of one’s identity, rather than an illness per
se. Where genetic markers for ASD are concerned, some in the neurodiversity
advocacy community may see the rapidly increasing discovery of gene markers for
ASD as a furthering of the ‘autism as a disease’ agenda. It may all be a matter
of one’s point of view, depending upon how comfortable one is with
understanding genetics as a feature of human identity, philosophically
speaking. For example, in breast cancer research, the BRCA1 and BRAC2 genes
have been linked to the disease (or identity, if you choose), and many more
genetic markers have been suggested.[9] Moreover, research indicates that many
breast cancer patients are ambivalent about their identity and human social
status after being diagnosed with the disease.[10]
But
what if human neurodiversity came to be understood in terms of our shared
Hominidae heritage? What if our shared genotypic heritage began to reveal that
we ‘act’ and ‘behave’ as we do, in many cases because our shared genetic
heritage? One might say such a thought is unremarkable, but let’s take that
line of inquiry a bit further, to ask the question: what if some human
diseases, such as some cases of human ASD, are caused by our shared Hominidae ancestry?[11] I
believe new evidence shows us exactly that fact.
I discovered the relationship between
human autism and duplicative 13q12 orangutan DNA insertions quite by accident,
while researching ASD. The relationship between these genetic duplications and
their impact on ASD remains little researched as of today, most likely because
of the grounding of such inquiry in the exploration of basic science, with
little hope for corollary pharmaceutical reward in the near future. While the
scientific literature shows that 13q12 duplications have been identified in
orangutans, and that orangutan duplication insertions also map to human 13q12,
no association has been declared between ASD and duplicative orangutan DNA
insertions. And yet, the association exists.[12]
As we’ve already discussed,
13q12 duplications have been rarely identified in autistic children. This is
not to suggest that 13q12 duplications will always cause ASD, but rather to
identify that in an otherwise healthy child that presents with a diagnosis of
ASD, with genetic testing revealing no other genetic abnormality other than a
13q12 duplication, that the 13q12 genetic duplication is highly suspect as the
cause of ASD. In other words, while the genetic expression of duplicated 13q12
in orangutans has no reported deleterious effect on that member of the
Hominidae family, and appears to be quite commonplace, in stark contrast,
something extraordinary may occur when the very same genetic duplication occurs
in humans: the birth of an autistic child. What remains to be explored now, is
the incidence of 13q12 duplications in the general population of Homo sapiens, with an analysis of the
increased risk for ASD such a genetic abnormality may pose to humans that
possess the genetic marker.
Conclusion:
Evolution and the Human Condition
We will continue to imagine what is true
about the human condition and what may be meaningfully said about it. Buried
deep in the circular maze of our souls, and our cells, remain vast tracts of
what we understand to be constitutive of Homo
sapiens. Though it may seem ordinary now, to talk of what is or is not in
our DNA, the truth is that the lion’s share of impulses that drive us and shape
our character and fate remains ambiguous, and even unknown. Perhaps unknown,
forever, because the prescient blind spot of self-analysis is the largest
impediment humanity has always faced. However little at a time, if we may, let
us advance unmasked, no?
an international and interdisciplinary journal of postmodern cultural sound, text and image
Volume 13, June -
October 2016, ISSN 1552-5112
Notes