Analysis of real-time PCR cycle threshold of alpha-thalassemia-1 Southeast Asian type deletion using fetal cell-free DNA in maternal plasma for noninvasive prenatal diagnosis of Bart's hydrops fetalis.
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 (deltaCp) between alpha-thalassemia-1 SEA type deletion gene (C(T-mutant)) and wild type alpha-globin gene (C(T-wild type)) in plasma of pregnancies by using the Taqman real-time quantitative PCR.


METHODS
Plasma DNA samples were collected from three groups of pregnancies whose fetuses have known thalasemia status (7 normal, 11 heterozygote alpha-thalassemia-1 SEA type deletion, and 7 Bart's hydrops fetalis). The alpha-thalassemia-1 SEA type deletion gene and wild type alpha-globin gene were quantified by using Taqman real-time quantitative PCR and then the delta C(T) was analyzed by subtracting the C(T-mutant) from C(T-wild type).


RESULTS
Mean deltaC(T) 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 deltaC(T) value than women whose fetuses were diagnosed as normal or heterozygote alpha-thalassemia-1 SEA type deletion (0 and 27%, respectively).


CONCLUSIONS
Further investigations are needed to improve the diagnosis of Bart's hydrops fetalis using fetal cell-free DNA.
Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand. sakornmi001@yahoo.com
Sakorn
S
Pornprasert
Kanyakan
K
Sukunthamala
Naowarat
N
Kunyanone
Sririchai
S
Sittiprasert
Khanungnit
K
Thungkham
Sumeth
S
Junorse
Khachonsilp
K
Pongsawatkul
Wisut
W
Pattanaporn
Chantip
C
Jitwong
Torpong
T
Sanguansermsri
D000510:Alpha-Globulins / Q000235:genetics*; D044466:Asian People / Q000235:genetics; D004247:DNA / Q000097:blood / Q000302:isolation & purification; D005260:Female; D005333:Fetus; D006455:Hemoglobins, Abnormal / Q000235:genetics; D006801:Humans; D015160:Hydrops Fetalis / Q000175:diagnosis* / Q000235:genetics; D009035:Mothers; D010949:Plasma / Q000737:chemistry; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis / Q000379:methods*; D017384:Sequence Deletion; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis* / Q000235:genetics
D000510:Alpha-Globulins; D006455:Hemoglobins, Abnormal; D004247:DNA; C030448:hemoglobin Bart's