title: Simplified PGD of common determinants of haemoglobin Bart's hydrops fetalis syndrome using multiplex-microsatellite PCR.
abstract: The high incidence of double-gene deletions in α-thalassaemia increases the risk of having pregnancies with homozygous α(0)-thalassaemia, the cause of the lethal haemoglobin (Hb) Bart's hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. However, the current gap-PCR based PGD protocol for deletional α-thalassaemia requires specific primer design for each specific deletion. A universal PGD assay applicable to all common deletional determinants of Hb Bart's hydrops fetalis syndrome has been developed. 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 analysed 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 IVF. A total of 47 embryos were analysed. Three pregnancies were achieved from three couples, with the births of two healthy babies and one ongoing pregnancy. This work has successfully adapted an 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. Alpha-thalassaemia is one of the most common inheritable disorders worldwide. It is a blood disorder that, in its lethal form caused by deletion of all four copies of the α-globin gene, results in the demise of the affected fetus, a condition referred to as haemoglobin (Hb) Bart's hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. Current PGD protocols for deletional α-thalassaemia utilize a strategy called gap-PCR, which requires the different assays for different deletion types. We have developed a universal PGD assay applicable to all common deletional determinants of Hb Bart's hydrops fetalis syndrome based on microsatellite marker analysis. 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 IVF. Forty-five embryos were analysed in total. Three pregnancies were achieved from three couples, with the births of two healthy babies and one pregnancy still ongoing. 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 the type of deletion.
authors.affiliation: Preimplantation Genetic Diagnosis Center, University Children's Medical Institute, Department of Pediatrics, Yong Loo Lin School of Medicine, National University Health System, Singapore 119074, Singapore.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.forename: Christine H A
authors.initials: CH
authors.lastname: Yap
authors.forename: Seong Feei
authors.initials: SF
authors.lastname: Loh
authors.forename: Arnold S C
authors.initials: AS
authors.lastname: Tan
authors.forename: Mui Nee
authors.initials: MN
authors.lastname: Lim
authors.forename: Ethiraj B
authors.initials: EB
authors.lastname: Prasath
authors.forename: Melinda L H
authors.initials: ML
authors.lastname: Chan
authors.forename: Wei Chin
authors.initials: WC
authors.lastname: Tan
authors.forename: Boran
authors.initials: B
authors.lastname: Jiang
authors.forename: Gare Hoon
authors.initials: GH
authors.lastname: Yeo
authors.forename: Joyce
authors.initials: J
authors.lastname: Mathew
authors.forename: Angela
authors.initials: A
authors.lastname: Ho
authors.forename: Sherry S Y
authors.initials: SS
authors.lastname: Ho
authors.forename: Peng Cheang
authors.initials: PC
authors.lastname: Wong
authors.forename: Mahesh A
authors.initials: MA
authors.lastname: Choolani
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Chong
mesh_terms: D005260:Female; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006801:Humans; D015160:Hydrops Fetalis / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D018895:Microsatellite Repeats; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods*; D055542:alpha-Globins / Q000235:genetics; D017085:alpha-Thalassemia / Q000175:diagnosis* / Q000235:genetics
chemical_list: D006455:Hemoglobins, Abnormal; D055542:alpha-Globins; C030448:hemoglobin Bart's