Disease Origin
Like with many other diseases and disorders, the specific cause or causes of ASD are unknown.
However, we do know that ASD results from altered brain development and a neural reorganization, which begin during early brain development. Although the exact reasons for these changes are unclear, certain risk factors for ASD have been identified.
The Study to Explore Early Development (SEED), a large national study led by the CDC, is investigating these risk factors and potential causes for ASD further. The known risks already include various genetic and environmental factors.
Genetics
- heterogeneous, individual genetic variants
- family history: having a twin or siblings with ASD
- Parental age: older parents (mothers over 40 and fathers over 50)
- Male gender
- Associated conditions: Down Syndrome, Fragile X Syndrome, Tuberous Sclerosis
In about 30% of individuals with ASD, some genetic risk factors have been identified. Many physician organizations recommend genetic testing in individuals with ASD to identify co-occurring medical problems, aid in prognosis, and connect individuals and families to specific support groups.
Environmental Factors
- Short pregnancy intervals: less than 2 years between pregnancies
- Premature birth: babies born before 26 weeks of gestation
- Birth weight: very low (<1,500g) and moderately low (<2,500g) birth weights
- Size at birth: babies who are very small or large for their gestational age
- Medication intake during pregnancy: Use of medication like valproic (prescribed for epilepsy, bipolar disorder, occasionally migraines) and thalidomide (prescribed to treat multiple myeloma and other hematologic malignancies)