Complex vs. Essential Autism
From Pediatric News October 2003 , Vol. 37 , No. 10
By Sally Koch Kubetin.
Columbia, MO. – Autistic children with dysmorphic facial features have a different variant of the disorder than do their nondysmorphic peers, Dr. Judith Miles said at a meeting on common pediatric problems sponsored by the University of Missouri-Columbia.
Children with what geneticists call dysmorphic features need not be
unattractive. “These can be cute kids, but on close inspection one can see
that something went awry during the first part of pregnancy,” said Dr.
Miles, who is a professor in the department of child health at the
university.
The dysmorphia can be subtle. Some examples include central posterior
hair whorl, frontal hair upsweep, medial left eyebrow flair, long flat
philtrum with attenuated philtral ridges, broad forehead, pointed chin,
small face, pointed finger nails, and small mouth.
Researchers only recently have begun to examine the clinical and
genetic heterogeneity of autism and have found some significant differences
in presentation. “About 30% of our autism clinic population [78/260
children] have complex autism,” she said.
In these children, autism occurs in combination with dysmorphic facial
features, microcephaly, and/or structural brain abnormalities on magnetic
resonance imaging. The ratio of boys to girls with complex autism is close
to 1:1, she reported.
The other variant of the disorder is essential autism. Affected
children do not have dysmorphic features, small heads, or structural brain
abnormalities; many more boys than girls have essential autism.
“Think of complex autism as being a sort of birth defect while
essential autism is more of a biochemical disorder that may involve
abnormalities of neurotransmitters,” said Dr. Miles, who is a geneticist.
Children with complex autism have higher rates of mental retardation
and seizures than do those with essential autism. However, essential autism
is more likely to run in families.
In a retrospective study, Dr. Miles collaborated with Matthew P.
Stoelb, Ph.D., of the department of education at the university, to look at
a group of 19 autistic children.
Dr. Stoelb conducted intensive, early, one-on-one therapy with the
children to help them acquire speech and overcome other developmental
delays; he worked with the children 22 hours weekly for 1 year.
Dr. Miles then applied her observations about dysmorphia in autism to
the children’s outcomes at the end of therapy. Findings from a linear
regression model showed that the presence of dysmorphia was the most
statistically significant predictor of failure to acquire language.
Increased Autism Prevalence Is Not An ‘Epidemic’ The increased
prevalence of autism over the past decade and a half does not represent an
epidemic, according to Dr. Miles.
She noted that the prevalence of autism has increased steadily over
the 15 years that she has been in the field. Autism affected 4-5 of every
10,000 children during the years before the 1990s; over the course of the
1990s, the prevalence increased to 16.8 cases/10,000 children.
Some parents are concerned that the increased prevalence of autism
reflects an epidemic, one that may result from an environmental factor such
as the use of mercury in vaccines. However, it is unlikely that the
increased prevalence is anything other than the result of detecting subtler
variants of autism.
“There are no epidemics in genetics, and autism has an inheritability
index of 90%,” she said. (Editor: See next article for an opposite point of view)
Many of the autistic children who are diagnosed now have higher IQs
than those diagnosed 15 years ago. “These are the kids whom we did not pick
up before because they were functioning well,” she said.
Copyright © 2003 by International Medical News Group, an Elsevier
company