In RBS, loss of ESCO2 acetyltransferase activity is crucial for proper sister chromatid cohesion [6] and most of the ESCO2 mutations described (88%) lead to a premature stop codon prior or within the acetyltransferase domain which is most likely the case of both mutations found in the reported RBS patient. The gene discussed is ESCO2; the disease is Roberts-SC phocomelia syndrome.