A distinct subgroup of these syndromes exhibit rare cytogenetic anomalies, for example, mosaic variegated aneuploidy syndrome (MVA)6–8 caused by variants in the spindle assembly checkpoint genes BUB1B, CEP57 and TRIP13, or rail-road chromosomes and premature chromatid separation (PCS) associated with Warsaw Breakage Syndrome (WABS) and Cornelia de Lange syndrome, caused by variants in the helicase DDX11 and components of SMC1/3 cohesin complex respectively9,10. Here, BUB1B is linked to Warsaw breakage syndrome.