Scientists have carried out a study
on variations in gene expression to understand the role of genes in individuals
Autism is a
heterogenous, complex, developmental condition that creates problems with
communications and social interactions.
Autism is a
"spectrum" disorder, as different autistic individuals exhibit different
symptoms. One person may display mild symptoms while in another, the
symptoms may be serious. But both are classified as autism spectrum disorders (ASD).
includes autistic disorder (classic autism), Asperger syndrome and pervasive
developmental disorder (atypical autism).
autism manifest before age three and
the condition delays the development of different skills, from infancy
to adulthood. Common problem areas include communication, social skills and
believed to be a familial trait and therefore inheritable. However the genetics
of autism are very complex.
In an effort
to understand how the genes control autism symptoms, Rui Luo, a graduate student working in the lab of David
Geschwind at the UCLA, and his colleagues studied blood cells called lymphoblasts
from 244 families that had an affected child and another that was not affected.
Luo and his
colleagues identified many potential new regions which contained copy-number
variants (CNVs) associated with ASDs and also found that the genes situated
within these regions were highly
misregulated and mis-expressed
in children with ASD, in comparison to their unaffected
siblings. These misregulated genes were
"hot spots" and a mutation in these variant regions was more likely in autistic
children than in their more fortunate siblings.
Geschwind, principal investigator and Luo's professor said "Strikingly, we
observed a higher incidence of haploinsufficient genes in the rare CNVs in
probands than in those of siblings, strongly indicating a functional impact of
these CNVs on expression."
Haploinsuffiency is known to occur when only a single copy of
a gene is functional, resulting in the
insufficient production of that specific protein.
looked at genes associated with nervous-system function we found significantly
more genes were expressed at higher or lower levels in the children diagnosed
with autism than we did in their siblings unaffected by the disorder…Our study
also demonstrates that even peripheral blood can expand our knowledge of
neurological disease," Geschwind
Geschwind is a
distinguished Professor of Human Genetics and professor of neurology at the
David Geffen School of Medicine at UCLA.
The scientists hope to find future therapeutic targets for
autism and are planning to replicate their study in a larger population.
etal, The American Journal of Human Genetics--June 21 (2012) Online edition