Monarch Disease Ontology term MONDO_0019040 (chromosomal disorder) is clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from Thompson et al., Genetics in Medicine, 5th ed, p429). Also known as: chromosomal disease, chromosomal disorders, chromosome disorder, disorder, chromosomal, disorder, chromosome, disorders, chromosomal, disorders, chromosome.