Drawing from the same sample population as Child Mind Institute Scientific Research Council member Matthew State, geneticist Michael Wigler has completed a parallel study and made some pretty bold statements about the causes of autism, the gender disparities in diagnosis, and possible related disorders. Wigler and his team undertook an analysis of the 1000 families of the Simons Simplex Collection with an eye towards bolstering what he calls his “unified theory of autism,” a theory that hasn’t found overwhelming favor in the wider community.
What is this shocking theory? Wigler has proposed that while autism is, indeed, heritable—passed from parents to children—the great majority of cases of the developmental disorder arise from “de novo,” or spontaneous, genetic mutations in the reproductive cells of the parents. Seems unlikely? Stay tuned.
By studying the genome of the parents, siblings, and the affected child in the Simons Simplex Collection, Wigler has concluded that there are perhaps 300 or more specific places in the genome that, if a mutation occurs, leads to autism. Hence, all that is needed to account for a majority of the cases we see is for a mutation to hit a relatively large target.
Since mutations occur with equal frequency across gender, Wigler needs to explain why four times as many boys are diagnosed with autism as girls. Here is Wigler’s big leap: He concludes that there are many girls with the same mutations as their male counterparts who are not symptomatic. Among those girls who are diagnosed, he notes, the damage done by mutation was much more extensive than the boys.
So that means that women are “resistant” to symptomatology, but can also be carriers, passing on the mutations to their children through simple hereditary transfer.
These carrier girls “may encounter difficulties at later stages of their lives that manifest as a different diagnostic category,” he told ScienceDaily. It’s “most likely to be one with a gender bias opposite that of ASD” like anorexia, he said. This seems to be idle speculation. But backing up a theory of autism with good data, a theory that could lead to prevention and new treatments, is alright in my book. The study is in Neuron.