The newly described syndrome is associated with microcephaly, short stature, developmental delay and delayed bone maturation. It has been reported in two unrelated patients. There is no remarkable facial dysmorphism. The clinical picture is opposite to that of patients with Sotos syndrome. The breakpoints of the duplication in both patients map to the proximal and distal low-copy repeats which flank the Sotos critical region. These findings support a non-allelic homologous recombination as the mechanism of duplication, and a dosage effect of the Sotos gene NSD1 (5q35). [from SNOMEDCT_US]