This aCGH study of 50 probands including patients fulfilling CdLS diagnostic criteria and those not completely fulfil the criteria [4], and negative for mutations at the NIPBL and SMC1A loci, led to the detection of four carriers of large genomic imbalances that are candidates to explain the clinical phenotype and represent a fraction (8%) of patients with features overlapping those of CdLS. The gene discussed is SMC1A; the disease is Cornelia de Lange syndrome.