title: 18ph+ is a normal chromosomal variant.
mesh_terms: D002869:Chromosome Aberrations / Q000175:diagnosis; D002871:Chromosome Banding; D025063:Chromosome Disorders; D002887:Chromosomes, Human, Pair 18 / Q000648:ultrastructure*; D003937:Diagnosis, Differential; D014644:Genetic Variation; D006570:Heterochromatin / Q000648:ultrastructure; D006801:Humans
chemical_list: D006570:Heterochromatin