New Cause For Autism Discovered

Researchers have finally provided a mechanism to explain why autism rates are so much higher in males than females.  The cause - a previously unrecognized cause of autism - a so-called germ line mutation.  Germ-line mutations are a different beast than other spontaneous DNA mutations, since your germ cells are are directly responsible for producing gametes.

For example, any mutation in a woman's egg cells (her germ line), accumulated will be passed on to 50% of her future children - 50% because each child shares half their DNA from each parent.  A more familiar example of germ-line mutations, then, is the relationship between ionizing radiation and birth defects.

Although parent's of either sex are just as likely to accrue such a defect, males were 3 times more likely to experience severe symptom of autism.  This suggests women were more likely to be carriers of this particular vector for autism.  Why?  Well, their sons inherit either one of their mother's X chromosomes, while inheriting their father's only Y chromosome.  Since sons will only have one copy of the X chromosomal genes, they will be more likely to express the full symptoms of their inherited disease.



Furthermore, the research group identified two groups or risk classes of parents with autistic children - a group carrying the germ-line mutation and one that does not.  As mentioned, women with the mutation can pass it on to their chidlren without actually displaying symptoms due to the nature of the mutation itself.