NSD1 and Sotos syndrome: In a girl (pt 45) with an atypical autism spectrum disorder and moderate mental impairment with absent expressive speech development, we detected a de novo ∼720-kb deletion at 5q35.3 that partially overlaps a common-sized ∼1.9-Mb recurrent deletion found in patients with Sotos syndrome (MIM 117550) but leaves the dosage-sensitive NSD1 gene (set domain protein 1; MIM 606681) intact (Fig. 1b, e).