Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Chromosome, marker
Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026
Chromosome, marker: An abnormal chromosome that is distinctive in appearance but not fully identified. A marker chromosome is not necessarily a marker for a specific disease or abnormality, but it can be distinguished under the microscope from all the normal human chromosomes. For example, the fragile X (FRAXA) chromosome was once called the marker X.