However, a central finding from these papers was that only a minority of cases had a de novo putatively functional variant, suggesting that this class of genetic variation is unlikely fully to explain the clinical entity of ASD. Indeed, estimates from de novo exonic mutations (similar to those from SV data) suggest that ASD is highly polygenic (estimates ranged from 400–1000 genes). 84,85 Importantly, a hypothetical model of ASD caused by rare but fully penetrant mutations in 100 different genes could be confidently rejected. 83
