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Decades of misconceptions give way to genetic breakthroughs
For years, autism was wrongly attributed to cold parenting. Now, researchers are identifying the genetic roots of the condition, revealing a complex interplay of inherited and spontaneous mutations.
The theory that autism stemmed from emotionally distant mothers-dubbed the "refrigerator mother" hypothesis-dominated psychiatry until the 1970s. UCLA neuroscientist Daniel Geschwind calls the idea "deeply damaging," noting it took decades to disprove. A pivotal 1977 study of identical twins finally shifted the narrative, showing autism often runs in families and has a strong genetic basis.
Twin studies reveal genetic links
Research shows identical twins share an autism diagnosis over 90% of the time, while fraternal twins of the same sex align in about 34% of cases. Both rates far exceed the general population's 2.8% prevalence. These findings confirmed genetics play a major role, though the specific genes involved remained elusive for years.
High-impact mutations and their consequences
Scientists have since identified "super strong" genetic variations in up to 20% of autism cases. These single-gene mutations, often arising spontaneously in embryos, can lead to severe disabilities, including intellectual impairments, motor delays, and epilepsy. Paris-based neuroscientist Thomas Bourgeron notes these cases differ sharply from the high-functioning portrayals often seen in media.
To date, over 100 genes have been linked to autism. Bourgeron's 2003 discovery of two mutations affecting neuron connections marked a turning point, though it drew little public attention at the time. More recent findings include mutations in the Shank3 gene, present in less than 1% of autistic individuals, and de novo variants-random mutations absent in parents' DNA.
Inherited traits and environmental factors
Not all mutations are spontaneous. Some are inherited from neurotypical parents, where the mutation alone isn't enough to cause autism but combines with other genetic variants to alter brain development. Environmental factors, such as prenatal exposure to pollution or premature birth, may also contribute, though research remains inconclusive.
The U.S. government's plan to accelerate autism research by September 2025-led by vaccine skeptic David Geier-has drawn criticism from groups like the Autism Society of America, who call the timeline "unrealistic and potentially harmful."
Brain development and genetic expression
Many autism-linked genes activate during fetal brain development, particularly in the cortex, which governs memory and problem-solving. Geschwind describes these mutations as "disrupting the normal developmental track," rerouting brain wiring in ways that diverge from neurotypical patterns.
Support groups, like the FamilieSCN2A Foundation, now use genetic insights to guide families. For parents of nonverbal children with motor delays, knowing whether a mutation is inherited or spontaneous can shape expectations about future development.
Controversies and ethical concerns
Genetic research has sparked debate within the autistic community. While some see it as a path to treatments for severe disabilities, others view autism as an identity-not a disorder to be cured. Edinburgh psychologist Sue Fletcher-Watson warns that prenatal testing could lead to eugenic outcomes, citing near-universal termination rates for conditions like Down syndrome in some countries.
"Autism isn't a biological phenomenon with a categorical outcome. It isn't universally agreed to be bad, and not everyone wants a cure."
Sue Fletcher-Watson, University of Edinburgh
Mount Sinai's Joseph Buxbaum counters that research should prioritize those with profound disabilities, arguing, "When I think about interventions, I'm thinking about people who will never live unsupervised."
Therapies and future directions
The Lancet Commission introduced the term "profound autism" in 2021 to describe individuals requiring lifelong support. Clinical trials are now targeting single-gene mutations, with some exploring gene therapy in utero. Bourgeron's lithium trial for Shank3 mutations and FDA-approved studies for Phelan-McDermid syndrome offer hope for families.
Yet Fletcher-Watson urges caution, suggesting these treatments address intellectual disability, not autism itself. She advocates for research into co-occurring conditions like epilepsy and OCD, which often accompany autism.
Balancing science and acceptance
Most autistic individuals inherit hundreds of common gene variants, each with minor effects. These variants, present in neurotypical and neurodivergent people alike, may explain traits like pattern recognition or mathematical aptitude. Bourgeron's collaboration with 23andMe linked poorer emotion recognition to specific gene groups, while Geschwind's team explores why autism is more prevalent in men.
Ultimately, Bourgeron emphasizes a nuanced approach: "We need to recognize neurodiversity and ensure those who function differently can flourish." Whether through medical intervention or societal accommodation, the goal remains supporting individuals across the spectrum.
