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 “Much of the research so far has identified genetic factors that
cannot be changed,” said Dr. Manish Arora of the Icahn School of
Medicine at Mount Sinai in New York.
“Our study is an important step towards understanding modifiable
risk factors such as exposure to environmental pollutants and
dietary deficiencies,” he told Reuters Health by email, “and the
most sensitive time periods when these exposures are harmful.”
However, he stressed, “it is too early to make clinical
recommendations.”
Arora and colleagues analyzed baby teeth from 16 pairs of identical
and fraternal twins in Sweden, with at least one sibling who had an
ASD diagnosis by the time they were about 18 years old. For
comparison, they also analyzed baby teeth from 22 twin pairs who
were developing normally.
A new tooth layer is formed every week or so during fetal
development and childhood. Each new layer is unique, and together,
over time, they provide a record of exposure to various chemicals.
“Teeth are like 'biologic hard drives' - information is constantly
being captured in their growth rings as teeth grow, starting in
prenatal development,” Arora said by email. “By uncovering
information from teeth, we can reconstruct what an individual
experienced in utero and in childhood.”
The team found significant differences in metal uptake between twins
with ASD and their healthy siblings at certain points in
development, they report in Nature Communications.
In late pregnancy and the first few months after birth, for example,
the teeth of children with ASD showed a higher uptake of lead - a
brain toxin - and a lower uptake of essential nutrients manganese
and zinc.
What’s more, three months after birth, the amount of toxic metals in
teeth could predict the severity of ASD at ages 8 to 10 years.
The authors note that the timing of unusually high or low uptake was
different for each of the elements examined in the teeth.
In addition, the researchers don’t know if differences in the amount
of toxic metals and nutrients in the teeth are due to how much a
fetus or child is exposed to, or to differences in how they absorb
and process these substances.
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The researchers also cannot say whether the disrupted uptake of
these substances at particular stages of late fetal and early
newborn development is a cause or an effect of autism. They suggest
that these alterations likely involve multiple disruptions in the
way metal uptake is regulated.
“Our genes and the genes of our babies are vulnerable to our ways of
living,” Dr. Eric Butter, who wasn’t involved in the research, told
Reuters Health by email. “What we eat, the air we breathe, and the
things we do can change the way our genes work,” Butter, who is
director of the Child Development Center and Pediatric Psychology/Neuropsychology
at Nationwide Children’s Hospital in Columbus, Ohio, told Reuters
Health by email.
The current study is helping researchers understand the “complicated
relationships” between genes, toxic metals and nutrients, and how
they may affect babies’ brains, Butter said.
But the study “is not saying anything about the metal exposures and
vaccine controversies that have plagued the autism community,” he
cautioned.
“As in many of the best scientific advances in our field, this study
opens many more important questions to be answered,” Butter said.
SOURCE: http://go.nature.com/2rok1DC Nature Communications, online
June 1, 2017.
(The story is refiled to correct name to Butter in paragraphs 15 and
16)
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