Simplified Preimplantation Genetic Diagnosis of Common Determinants of Hemoglobin Bart’s Hydrops Fetalis Syndrome Using a Multiplex- Microsatellite PCR Assay

The high incidence of double-gene deletions in α-thalassemia increases the risk of having pregnancies with homozygous α0-thalassemia, the cause of the lethal hemoglobin (Hb) Bart’s hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. However, current gap-PCR based PGD protocol for deletional α-thalassemia required specific primer design for each specific deletion. We have developed a universal PGD assay applicable to all common deletional determinants of Hb Bart’s hydrops fetalis syndrome. Microsatellite markers 16PTEL05 and 16PTEL06 within the α-globin gene cluster were co-amplified with a third microsatellite marker outside the affected region in a multiplex-PCR reaction and analyzed by capillary electrophoresis. Eight informed couples at risk of having Hb Bart’s hydrops fetalis were recruited in this study and all patients underwent standard procedures associated with in-vitro fertilization (IVF). 45 embryos were analyzed in total. Three pregnancies were achieved from three couples, with the births of two healthy babies and one ongoing pregnancy. We have successfully adapted our earlier protocol and developed a simple and reliable single cell assay applicable to PGD of Hb Bart’s hydrops fetalis syndrome regardless of type of deletion.