Chromosomal Microarray (CMA) replacing traditional Karyotyping in HA Prenatal Diagnosis Service

Abstract

Traditional karyotyping had been the standard test for prenatal diagnosis in Hong Kong since 1981. Chromosomal microarray (CMA), either performed by array comparative genomic hybridization (aCGH) or single nucleotide polymorphism (SNP) array has become more widely used 30 years later. CMA offers increased diagnostic yield on detection of submicroscopic changes (microdeletions and microduplications) not detected by karyotyping and at a shorter reporting time. The new workflow of using CMA as primary test in HA prenatal diagnostic service include rapid aneuploidy detection by quantitative fluorescent polymerase chain reaction (QF-PCR) to exclude trisomies 13, 18, 21, monosomy X and triploidy (these aneuploidies would proceed to karyotyping only). Those with normal QF-PCR results would proceed to CMA. The new workflow would be offered to patients who undergo invasive prenatal diagnosis, stillbirth and second trimester miscarriage. The cost-effectiveness of the new algorithm can be demonstrated from both the healthcare system and societal perspectives. This shall enhance patient access to improved clinical laboratory service and patient care pathways in prenatal diagnosis.