2 Introduction to Autism Spectrum Disorders
In the process of scientific research, data occasionally emerge that cannot be
easily correlated with present theories. Still, scientists, like others, are naturally
reluctant to adopt new theories when established concepts still appear viable,
although in need of major updates or revision. Typically, the effects of such
scientific reluctance manifest themselves in enlivened discussions at profes
sional conferences, in academic circles and journals, or in books written by
journalists, scientists, and medical doctors. In the area of autism pathogenesis,
however, the consequences of decades of inadequate progress in coming to
grips with the basic underlying biology of autism spectrum disorder (ASD)
may be calculated not in journal publications, but in the quality of human lives
for literally millions of silent offspring, and even more desperate parents, who
find themselves bewildered at the effects of the disorder on both their children
and themselves. This alarming rise in autism is not a case of some sudden rise
in avian flu from the 1950s, or the unexpected Ebola epidemic in West Africa a
few years ago that could have rapidly killed millions but fortunately quickly
burned itself out. Another case in point is the epidemic of Zika virus, which is
harming unborn fetuses that are then born with small heads (microcephaly)
but this is also bound to pass within a couple of years. These are the cases that
we may hear about now but then not again for decades or even centuries until
they rise again, like the proverbial phoenix.
The traditional paradigm regarding the underlying causes of autism asserts
that it is a genetic disease that emerges when children inherit two bad genes
from their parents that show up in the toddler (in genetic terms, recessive
genes). Although thousands of genes or genetic mutations have been suggested
as links to autism by a growing number of scientists, none provides the causa
tive link that is clearly authentic and replicable. As appealing as the bad genes
explanation appears at a superficial level, this fails to withstand scientific scru
tiny. A fundamental reason why autism cannot be labeled as simply a genetic
disease is that genes simply do not change that fast. And so many genes (now
numbering in the thousands) cannot be responsible for causing ASD – a spec
trum of heterogeneous symptoms.
Consider sickle cell anemia. It results from the replacement of a single nucle
otide in the beta‐globin chain, which occurred among our ancestors, some
where in Africa, in the far distant past. This genetic adaptation to the
malaria‐infested environment produced a defective gene that has been inher
ited. A child, who inherits just one gene (i.e., sickle trait) from just one parent,
is protected against deadly malaria, but a minority of the children will inherit
the defective gene from both parents and succumb to sickle cell disease. If a
corrective major mutation could take place in decades, sickle cell anemia would
have disappeared eons ago when people of African descent migrated to the
Americas between two hundred and four hundred years ago.
The emergence of sickle cell anemia gives additional evidence of natural
selection and mutation that has affected countless individuals. The