Our results confirmed the importance of relative macrocephaly and protruding forehead among NH-CSS criteria due to the high prevalence of “clinical SRS” in four patients with variants in the responsible genes for SRS (IGF2, CDKN1C, and PLAG1) and the low prevalence of “clinical SRS” in five patients with variants in causative genes for known genetic syndromes. This evidence concerns the gene PLAG1 and Silver-Russell syndrome.