The most often mutated gene in our NDD cohort was ARID1B, accounting for 0.3% of all DNVs as well as the highest proportion of dnLGD variants (dnLGD = 0.25%, dnMIS = 0.05%, dnMIS30 = 0.02%) (Figure 1A,B, Table 2 and Table S3). Here, ARID1B is linked to Neurodevelopmental delay.