PSMB5 and Roberts-SC phocomelia syndrome: In contrast to CdLS, cohesion defects have been reported in three human developmental disorders: RBS (OMIM 268300) [19], Rothmund–Thomson syndrome (RTS, OMIM 268400) [44], and α-Thalassemia/mental retardation syndrome, X-linked (ATRX, OMIM 301040) [45].