Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual two copies.
Causes, incidence, and risk factors
Trisomy 18 is a relatively common syndrome. It is three times more common in girls than boys. The syndrome is caused by the presence of extra material from chromosome 18. The extra material interferes with normal development.
Half of infants with this condition do not survive beyond the first week of life. Some children have survived to the teenage years, but with serious medical and developmental problems.
Complications depend on the specific defects and symptoms.
Calling your health care provider
Genetic counseling can help families understand the condition, the risks of inheriting it, and how to care for the patient.
Tests can be done during pregnancy to determine if the child has this syndrome.
Genetic testing is recommended for parents who have a child with this syndrome who want additional children.
Chad Haldeman-Englert, MD, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.