To get new insights into the relationship between ESCO2 mutations, cytogenetic anomalies and clinical features in Roberts syndrome, we performed 3D-FISH using pericentromeric heterochromatin (PH) probes of chromosome 1, 4, 9 and 16 on fibroblasts and cytotrophoblasts nuclei of a patient with molecularly defined RBS. This evidence concerns the gene ESCO2 and Roberts-SC phocomelia syndrome.