DMPK and myotonic dystrophy type 1: The most significant SNP was rs527221, a nonsynonymous variant in the DMPK gene, which is responsible for causing type 1 myotonic dystrophy, severe childhood forms of which have been associated with ASD (Ekström, Hakenäs‐Plate, Samuelsson, Tulinius, & Wentz, 2008).