A rare chromosomal disorder with a highly variable clinical presentation. Most patients have multiple malformations affecting the eyes (iris coloboma), ears (preauricular pits and/or tags), anal region (anal atresia), heart and kidneys. Intellectual disability is usually mild or borderline normal. Most patients have a small supernumerary bi-satellited marker chromosome that results in partial tetrasomy of 22pter-22q11. In one third of cases, this extra chromosome is present in a mosaic state. Other cytogenetic anomalies have been rarely reported, including partial trisomy of chromosome 22 and intrachromosomal triplication of the 22q11 region.