Analysis of Real-Time PCR Cycle Threshold of ααααα-Thalassemia-1 Southeast Asian Type Deletion Using Fetal Cell-Free DNA in Maternal Plasma for Noninvasive Prenatal Diagnosis of Bart’s Hydrops Fetalis
Sakorn Pornprasert PhD*, Kanyakan Sukunthamala BSc**, Naowarat Kunyanone MSc***, Sririchai Sittiprasert MSc***, Khanungnit Thungkham MSc****, Sumeth Junorse BSc****, Khachonsilp Pongsawatkul MD****, Wisut Pattanaporn MD**, Chantip Jitwong MD*****, Torpong Sanguansermsri MD******
Affiliation : * Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand ** Health Promoting Hospital Chiang Mai, Chiang Mai, Thailand *** Chiang-Rai Hospital, Chiang Rai, Thailand **** Phayao Hospital, Phayao, Thailand ***** Lamphun Hospital, Lamphun, Thailand ****** Division of Hematology, Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Background : Noninvasive prenatal diagnosis based on detection of fetal cell-free DNA is hampered when mother and father
are both carriers for the same autosomal recessive mutation.
Objective : To compare the diagnosis of Bart’s hydrops fetalis using conventional Gap-PCR analysis of fetal cells/tissues
with the measurement of quantitative difference (ΔCT) between α-thalassemia-1 SEA type deletion gene (CT-mutant) and wild
type α-globin gene (CT-wild type) in plasma of pregnancies by using the Taqman real-time quantitative PCR.
Material and Method: Plasma DNA samples were collected from three groups of pregnancies whose fetuses have known
thalasemia status (7 normal, 11 heterozygote α-thalassemia-1 SEA type deletion, and 7 Bart’s hydrops fetalis). The
α-thalassemia-1 SEA type deletion gene and wild type α-globin gene were quantified by using Taqman real-time quantitative
PCR and then the ΔCT was analyzed by subtracting the CT-mutant from CT-wild type.
Results : Mean ΔCT values were not significantly different among the three groups. However, women whose fetuses were
diagnosed as Bart’s hydrops fetalis had a higher proportion (43%) of plasma DNA samples that had negative ΔCT value
than women whose fetuses were diagnosed as normal or heterozygote α-thalassemia-1 SEA type deletion (0 and 27%,
respectively).
Conclusion : Further investigations are needed to improve the diagnosis of Bart’s hydrops fetalis using fetal cell-free DNA.
Keywords : α-thalassemia-1 SEA type deletion, Bart’s hydrops fetalis, Fetal cell-free DNA, Prenatal diagnosis, Real-time PCR
