Molecular Karyotyping: A Revolutionary Concept in Prenatal Diagnosis

The ‘standard of care’ for chromosome testing has recently changed. For the last 30 years it has involved chromosome testing using microscope analysis. New technology using ‘DNA chips’, i.e. molecular karyotyping or microarray has now become available and is routinely offered to pregnant women undergoing invasive testing for an ultrasound detected fetal abnormality.Women who choose to take advantage of this technology undergo extensive counselling in a multidisciplinary setting regarding the possible implications of an abnormal result. They are advised that there are some molecular changes which are known to be harmless and will not be reported. They are also counselled that some molecular changes will be reported but their clinical significance is uncertain.This article reviews the current evidence-based role of molecular karyotyping in routine clinical practice in the setting of ultrasound detected fetal abnormality.