ITSN1 haploinsufficiency has also recently been implicated in moderate forms of ASD.17 Other studies have highlighted a convergence between ASD and PD, with epidemiologic data suggesting that people with ASD are three times more likely to develop parkinsonism.41 Synaptic transmission dysfunction is emerging as a convergent mechanism between neurodevelopmental and neurodegenerative disease.42,43 Interestingly, the association between ITSN1 and ASD was driven in part by rare PTVs that probands inherited from unaffected parents. Here, ITSN1 is linked to Parkinsonism.