Silver Russell Syndrome (SRS) includes pre and postnatal growth retardation, severe feeding difficulties, protruding forehead, relative macrocephaly at birth and body asymmetry. A simple clinical definition of SRS is important to establish its prevalence, propose clinical guidelines and common clinical trials for this group of patients and allow research to progress for patients with no molecular cause identified yet. We validate, on a prospective study, a new scoring system very sensitive (98%) for the detection of SRS patients with demonstrated molecular abnormalities. Given its clinical and molecular heterogeneity, SRS could be considered as a spectrum. (By Salah Azzi, http://jmg.bmj.com/content/early/2015/05/07/jmedgenet-2014-102979 )