EDITORSupernumerary marker chromosomes are rare with an incidence of 0.3-1.5/1000 newborns. Most carriers have a normal phenotype but in 15% of non-satellited marker cases mental retardation and minor anomalies have been reported.¹ The origin of several supernumerary ring marker chromosomes has been identified by fluorescence in situ hybridisation (FISH).² The VATER association is characterised by non-random occurrence of Vertebral anomalies, Anal atresia, Tracheo-oesophageal fistula with Esophageal atresia, Radial limb dysplasia, and Renal defects.³ The acronym VACTERL is used in cases with additional Cardiac and Limb malformations.⁴ VACTERL with hydrocephalus is thought to be an autosomal recessive disorder distinct from the VATER association.⁵ Other defects that occur less frequently have been also described.⁶ A defect in blastogenesis was suggested as a possible aetiology of this malformation spectrum. Martìnez-Frìas et al⁷ proposed that combinations of anomalies of blastogenetic origin, such as VATER/VACTERL, should be considered and called "polytopic field defects" . . . [Full text of this article]