Download Scientists Tie Two Additional Genes to Dyslexia

ARIVE 3.3.1 (may need to reorganize)
Directions and video transcript for Think Aloud
Directions:
1. Link to this article on the genetic basis of dyslexia
2. Read the article. Try to be aware of your inner dialogue between your mind and the
article.
3. Watch the video (listen to the audio) of Linda Hecker modeling how she “Thinks
Aloud” about the article
http://www.cdl.org/resource-library/articles/genes_to_dyslexia.php?type=recent&id=Yes
Scientists Tie Two Additional Genes to
Dyslexia
This article sounds really interesting to me because I’ve been following the story of
genetics and dyslexia for a while. I know scientists have been trying to identify
specific genes that are connected to dyslexia. I think I heard a while ago that
specific chromosomes 6, 9, and 15 might be involved. I haven’t kept up with what’s
happened in the last few years. This should help me stay current.
by SANDRA BLAKESLEE
I wonder who Sandra Blakeslee is? I don’t think she’s a scientist. Is she a science
reporter? How accurate is her writing? Will it be hard to understand for a lay
person?
October 29, 2005
One year after scientists discovered a gene whose flaw contributes to dyslexia, two more
such genes have now been identified.
I didn’t even know about the last discovery. I’m really behind on my research.
The findings, described yesterday in Salt Lake City at a meeting of the American Society
of Human Genetics, support the idea that many people deemed simply lazy or stupid
because of their severe reading problems may instead have a genetic disorder that
interfered with the wiring of their brains before birth.
I can’t believe anyone still believes in the “stupid or lazy” theory of dyslexia. We’ve
known for a long time that dyslexic brains look and act differently than the brains
of typical readers. And I still don’t agree that it’s a “disorder.” I think it’s a brain
variant that’s essential to the gene pool.
"I am ecstatic about this research," said Dr. Albert M. Galaburda of Harvard Medical
School, a leading authority on developmental disorders who was not involved in the latest
discoveries.
Oh- Al Galaburda. I wondered if he was still involved in dyslexia research. I
haven’t seen him in several years. He used to talk at the IDA conferences. I loved
hearing about his research. He wasn’t into genetics so much as post-mortem
autopsy studies, but he was the first researcher who turned me on to the brain
difference theory of dyslexia.
The findings, added to last year's, mean that for the first time, "we have a link between
genes, brain development and a complex behavioral syndrome," Dr. Galaburda said.
If Al Galaburda thinks this is hot stuff, I need to pay close attention.
As many as a dozen genes are probably involved in the disorder, he said, with each
playing a role in the necessary migration of neurons as the brain's circuitry develops.
I knew it couldn’t be as simple as 1 or 2 genes.
Researchers said a genetic test for dyslexia should be available within a year or less.
Children in families that have a history of the disorder could then be tested, with a cheek
swab, before they are exposed to reading instruction. If children carry a genetic risk, they
could be placed in early intervention programs.
Omigod – really genetic testing for dyslexia only a year away! I hope no one thinks
it would be good to genetically engineer fetuses to avoid dyslexia.
"Reading ability is a proxy for intelligence in American culture,"
said Dr. Sally E. Shaywitz of Yale University School of Medicine, a pediatrician who is
an expert on dyslexia. The findings should help overcome stereotypes and get children
the assistance they need, she said.
Naturally, I’d expect Sally Shaywitz to weigh in on this issue.
One of the genes newly linked to dyslexia is called DCDC2. It is active in reading centers
in the human brain, said Dr. Jeffrey R.
Gruen, a Yale geneticist who described the discovery at a news conference yesterday.
Large deletions in a regulatory region of the gene were found in one of every five
dyslexics tested, making it less active.
This part is news to me. I never heard of DCDC2. Funny name. It needs a
nickname. So, it seems to be about missing stuff in the genes.
Fluent readers and dyslexics alike have the protein made by this gene, Dr. Gruen said, but
it is less abundant in dyslexic brains.
The function of the protein is not known, he said.
Again, it’s interesting that it’s not an all or nothing control system, but a question of
not having enough of something to function correctly. I’m not surprised they don’t
know the protein’s function yet.
Rats also have the DCDC2 gene, so it should not be misconstrued as a spelling or reading
gene, Dr. Gruen said. Rather, the gene supports the circuitry that underlies reading. When
it was perturbed in unborn rats, he said, neurons migrated shorter distances, undercutting
early brain development.
Hmmm. This is the most interesting part of all. It reminds me of Ginger
Berninger’s book, “Brain Literacy for Educators.” She really stresses that the
reading parts of the brain are built out of areas originally designed for other
functions, because reading isn’t actually a “natural” process that is hard wired into
human brains.
The second gene, called Robo1, was discovered by Dr. Juha Kere, a professor of
molecular genetics at the Karolinska Institute in Stockholm. It is a developmental gene
that guides connections, called axons, between the brain's two hemispheres, Dr. Kere said
in an interview.
mmm. very interesting. This is the first I’ve heard of connecting the 2 hemispheres.
When the gene's activity is reduced, the number of finer connections, called dendrites, is
reduced in brain areas involved in reading.
"You get the right signals going, but they do less well in terms of rapid processing," Dr.
Kere said.
Many dyslexia experts believe that reading problems stem from an inability to process
the fast sounds of spoken words.
More points for Paula Tallal’s research on rapid processing of sounds.
This is fascinating. I can’t wait to hear more about this research.
THINK ALOUD SCRIPT