[extropy-chat] Fwd: CNN features amazing user with autism

Robert Bradbury robert.bradbury at gmail.com
Sun Feb 25 08:31:53 UTC 2007


I hadn't looked at this recently and was surprised when I did so I thought I
would share it.  Apparently there has been a lot of work done on the
genetics of Autism & Asperger's Syndrome.  Currently NLM OMIM is listing at
least 10 chromosome locations involving susceptibility to autism including 3
which are X-linked (perhaps explaining why it is more common among men).
Asperger's has a list of gene locations almost as long with significant
overlap with the Autism genes.  Some of the locations have been pinned down
to specific genes some have not.

I have recently been investigating some critical DNA repair genes and so I
was looking at the Human HapMap for variation in those genes.  The people
working on the HapMap have nicely classified mutations into "green" and
"red" variations (green not resulting in a change in the amino acid sequence
of a protein, red causing a change in the amino acid sequence).  As it
turned out in the 8 genes I looked at, the average was 4+ *red* variations
*per* gene! [1]  (And these are core DNA repair genes -- you can't vary them
much without really messing things up.  Genes which have a lesser impact on
the survival of the organism could vary much more.)

This isn't the junk DNA -- this is the actual hardware that goes to make up
your computer's instruction set.  So given 10+ genes involved in these
conditions we are talking about 40+ variations (which could be present in a
wide range of combinations) in this set of genes which seems to involve
fundamental differences in neuronal architecture and functioning.

So even though the people across the diner table from you, sitting next to
you in the car, walking all around the airport may look like you, walk like
you and if you are lucky talk like you, they are only "like" you in the
sense that the are more like you than they are like Sandi [2].

Robert

1. The extent to which the change of a single amino acid alters the function
of a protein varies.  Some changes have only a minor effect.  Other changes
can alter function significantly or make the protein completely
dysfunctional.  One would tend to believe that variations which are common
in the human HapMap would tend to be on the minor to middle of harm range.
But the effects might be masked by the other "good" copy of the gene
(protein).  It isn't clear what impacts one gets if one is producing 50%
"bad" and 50% "good" protein copies particularly with an organ as complex as
the brain.
2. http://www.discoverchimpanzees.org/chimps/sandi_bio.php
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