The development of novel quantification assay for mitochondrial DNA heteroplasmy aimed at preimplantation genetic diagnosis of Leigh encephalopathy.
OBJECTIVE
To perform preimplantation genetic diagnosis (PGD) of Leigh encephalopathy, we developed a rapid and reliable quantification assay for the percentage of T8993G mtDNA mutation and analyzed various specimens.


METHODS
We prepared the standard curve by measuring serial proportion of 8993T/G cloned plasmid DNA using real-time PCR, and measured (1) mutant DNA (known proportions by PCR-RFLP), (2) single lymphocytes from 46% mutant carrier, (3) 123 blastomeres from 20 abnormal embryos.


RESULTS
(1) These were within -5 - +6% error range, (2) mean 44.3%(11-70%), (3) Five embryos harbored T8993G mutation (4-22%). Embryos from same person indicated different degrees of heteroplasmy, and blastomeres from same embryo demonstrated limited dispersion of heteroplasmy (2-11%).


CONCLUSIONS
(1) This method provides rapid and reliable PGD for Leigh encephalopathy. (2) The variable heteroplasmy with somatic mitosis was suggested. (3) T8993G mutation was existed in undeveloped embryo, and the bottleneck theory was supported. The limited heteroplasmy dispersion of blastomeres from same embryo also supported reliability of PGD for T8993G mutation.
Tajima
Hiroto
H
Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, Japan. tajima@rc5.so-net.ne.jp
Sueoka
Kou
K
Moon
Sung Yung
SY
Nakabayashi
Akira
A
Sakurai
Tomoyoshi
T
Murakoshi
Yukitaka
Y
Watanabe
Hiroyoshi
H
Iwata
Soukichi
S
Hashiba
Tsuyoshi
T
Kato
Shingo
S
Goto
Yu-Ichi
Y
Yoshimura
Yasunori
Y
D001483:Base Sequence; D001757:Blastomeres / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D004252:DNA Mutational Analysis / Q000379:methods; D004272:DNA, Mitochondrial / Q000032:analysis*; D005240:Feasibility Studies; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods*; D006801:Humans; D007888:Leigh Disease / Q000175:diagnosis* / Q000235:genetics; D008214:Lymphocytes / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D019836:Preimplantation Diagnosis / Q000379:methods*
D004272:DNA, Mitochondrial; C501005:MT-ATP6 protein, human; D025261:Mitochondrial Proton-Translocating ATPases