Boys diagnosed with autism far outnumber their female counterparts. Autism genetics researcher Ivan Iossifov lays out what research into the disorder’s genetic basis reveals about the reasons for this striking pattern.
Many of the numbers pegged to autism are staggering. By some estimates, as many as 1 in 68 children lies somewhere along the autism spectrum. Experts predict that as many as 500 or even 1,000 of the 20,000 genes in the human genome have the potential to contribute to autism if damaged. But perhaps the most baffling statistic is that a boy鈥檚 risk of autism is roughly quadruple that of a girl.Scientists have yet to solve this mystery, but autism genetics researchers such as CSHL Assistant Professor Ivan Iossifov have uncovered some clues.
Certain genes that all humans have are particularly likely to contribute to autism if damaged. Iossifov and his colleagues have identified over 200 of these autism 鈥渞isk genes鈥� so far.
Autism鈥檚 bias against boys is a key element of the 鈥渦nified theory of autism鈥� that Iossifov鈥檚 colleague, CSHL Professor Michael Wigler, proposed in 2007. So far, the that girls are to some degree protected from the effects of damaging genetic mutations.
Michael Wigler explains his ‘unified theory of autism’
Iossifov notes that, based on research he, Wigler and other colleagues have conducted in recent years, 鈥淲hen you look at girls, all the girls with autism have more, and more severe, damaging mutations compared to boys with autism.鈥�
Boys and girls seem to have different thresholds for damage to autism risk genes. While boys with relatively little damage to autism risk genes may develop the disorder, girls typically only develop autism when they have mutations鈥攕ometimes in the same genes鈥攖hat scientists describe as 鈥渄evastating.鈥�
This observation is just the beginning of the scientific journey to understand whether girls are in fact 鈥減rotected鈥� in some manner from some autism-causing mutations, and if so, what exactly protects them. One of the major factors in the way of this research, according to Iossifov, is that there are simply fewer girls with autism available to study. Advances in genetic sequencing techniques are helping to reduce this research barrier, however, by making genetic information more accessible.
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Note:聽For the sake of simplicity, this article uses the term 鈥榓utism鈥� to refer to all autism spectrum disorders (ASDs). You can find out more about the distinction between autism and ASD here.