Detection of paternal alleles in maternal plasma for non-invasive prenatal diagnosis of beta-thalassemia: a feasibility study in southern Chinese.
OBJECTIVE
To evaluate in maternal plasma, the efficacy of detecting the paternal beta-gene mutation and informative single nucleotide polymorphisms (SNPs) linked to the paternal-mutant or -normal allele in non-invasive prenatal diagnosis (NIPND).


METHODS
In 20 at-risk pregnancies, using the allele-specific arrayed primer extension (AS-APEX) technology of the previously published "Thalassemia" array, cyanine-5-deoxycytosine triphosphate (Cy5-dCTP) was incorporated into the extended strands to matched PCR-amplified maternal plasma DNA templates, to detect both the paternal beta-gene mutation and informative paternal SNPs.


RESULTS
Sensitivity experiment showed that 5pg DNA as starting template gave detectable signals on the array. In 13 cases (65%), the paternal-derived beta-gene mutation and/or informative mutant-associated SNP were detected. A subsequent invasive procedure was required to determine if the fetus had a beta-thalassemia (thal) major or minor genotype. In 3 cases (15%), absence of the paternal mutant or mutant-associated SNP excluded a beta-thal major fetus; while in 4 cases (20%), this approach was non-discriminative as both parents carry the same mutation without any informative SNP.


CONCLUSIONS
This approach was useful in 16 out of 20 (80%) pregnancies at risk for beta-thal in southern Chinese.
Chan
Kaimin
K
University Department of Medicine, Queen Mary Hospital, Hong Kong.
Yam
Irene
I
Leung
K Y
KY
Tang
Mary
M
Chan
T K
TK
Chan
Vivian
V
D000483:Alleles; D044466:Asian People / Q000235:genetics; D002232:Carbocyanines; D003845:Deoxycytosine Nucleotides; D005220:Fathers; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D055544:beta-Globins / Q000235:genetics; D017086:beta-Thalassemia / Q000175:diagnosis* / Q000235:genetics
D002232:Carbocyanines; C544355:Cy5-dCTP; D003845:Deoxycytosine Nucleotides; D055544:beta-Globins