Examples are mutations in the EZH2 (Weaver syndrome) and DNMT3A (Tatton-Brown-Rahman syndrome) which cause overgrowth, but are also candidates for the Facioscapulohumeral Dystrophy (FSHD) with a wide heterogeneity of disease, complicating FSHD diagnosis and the genotype-phenotype correlation among patients and within families. This evidence concerns the gene EZH2 and Facioscapulohumeral dystrophy.