Ped Med: Studies look at heredity, autism

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Ped

Med: Studies look at heredity, autism

By LIDIA WASOWICZ

UPI Senior Science Writer

SAN FRANCISCO,

Dec. 13 (UPI) -- Autism investigators are collecting clues

about genes that may be responsible for inherited traits which by themselves do

not cause the disorder but may be associated with it.

A number

of scientific teams have set their sights on these so-called

" endophenotypes " -- which can be behavioral or biological -- in the

kin of autistic children.

Once they

recognize the telling traits in families with autistic members, they can sift

through their gene pool for any changes, or " mutations, " that might

be responsible for said characteristics, researchers explained.

The

endophenotypes for autism reported thus far include: a large head size in the

child's kindred, the parents' abnormal brain processing of faces and relatives'

diminished ability to read another person's mental state, among others,

scientists said.

" As

we identify endophenotypes and their related genes, such as for language delay,

we will be homing in on genes for autism, " said Dr. Geschwind,

associate professor of neurology, director of the Neurogenetics Program and the

Center for Autism Research and Treatment at the University of California, Los

Angeles, School of Medicine, and author of " Microarrays for the

Neurosciences " (MIT Press, 2002).

" This

is one of the most exciting developments in the field of autism genetics

today, " he added.

Geschwind

said his recent research illustrates the importance of such traits as

guideposts for zeroing in on autism-related regions in the vastly complex

landscape of the human genome.

Steered

by behavioral symptoms of the autistic children in their study, the scientists

headed to the area, on chromosome 17, thought to harbor the corresponding gene

for the social impairment.

Chromosomes

are threadlike structure at the heart of each cell composed of

heredity-harboring deoxyribonucleic acid, or DNA

Geschwind

and his team duplicated their initial effort in a separate population. They

said the achievement marked the first time such a finding was made and

replicated, a key step in the scientific process of discovery.

In an

earlier investigation, the scientists were surprised to find the gene they were

targeting contributes to autism only in boys, perhaps explaining why males face

a dramatically higher risk of developing the disorder than do females, they

said.

The

researchers' next task is to settle on the precise site within the chromosomal

region they have linked to the genetic alteration responsible for the social

deficit.

" The

first step is finding the region of the genome, what we call the locus. It's

like you're in Kansas,

and you need to find the haystack where the needle is, " Geschwind explained.

" We've found the haystack -- the location of the gene -- but not yet the

needle -- the gene itself. "

Geschwind

thinks the way to autism's genetic core, and perchance its cure, is through its

individual parts.

" Autism

is caused by many genes acting together, we think, causing different aspects of

the disorder, " he said.

" If

we divide it up and look (separately) at the aspect related to language and

other features that are easier to measure, such as head size or social or

repetitive behavior, that will move us closer to finding the genes, " he

added.

" Once

the gene is located, the next step is to understand how that gene affects brain

function, " he concluded. " Once the gene's function is understood,

then scientists can measure the impact of various environmental agents on that

function. "

As with

studies examining the diverse ways different types of mercury course through

the body, the findings provide a critical piece of the autism puzzle, but not

telling enough to solve the jigsaw.

(Note: In

this multi-part installment, based on dozens of reports, conferences and

interviews, Ped Med is keeping an eye on autism, taking a backward glance at

its history and surrounding controversies, facing facts revealed by research

and looking forward to treatment enhancements and expansions. Wasowicz is the

author of the forthcoming book, " Suffer the Child: How the Healthcare

System Is Failing Our Future, " to be published by Capital Books.)

Next:

Autism as a multi-faceted disorder

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