Clinical application of sequencing-based methods for parallel preimplantation genetic testing for mitochondrial DNA disease and aneuploidy

Preimplantation genetic testing can help carriers of mtDNA mutations avoid affected pregnancies and can be combined with aneuploidy testing. Results provide information on recurrence risk and potential disease transmission mechanisms.

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VOLUME 115, ISSUE 6, P1521-1532

Authors:

Katharina Spath, Ph.D. , Dhruti Babariya, Ph.D., Michalis Konstantinidis, Ph.D., Jo Lowndes, M.Sc., Tim Child, Ph.D., James A. Grifo, Ph.D., Joanna Poulton, Ph.D., Dagan Wells, Ph.D.

Abstract:

Objective

To validate and apply a strategy permitting parallel preimplantation genetic testing (PGT) for mitochondrial DNA (mtDNA) disease and aneuploidy (PGT-A).


Design

Preclinical test validation and case reports.


Setting

Fertility centers. Diagnostics laboratory.


Patients

Four patients at risk of transmitting mtDNA disease caused by m.8993T>G (Patients A and B), m.10191T>G (Patient C), and m.3243A>G (Patient D). Patients A, B, and C had affected children. Patients A and D displayed somatic heteroplasmy for mtDNA mutations.


Interventions

Embryo biopsy, genetic testing, and uterine transfer of embryos predicted to be euploid and mutation-free.


Main Outcome Measures

Test accuracy, treatment outcomes, and mutation segregation.


Results

Accuracy of mtDNA mutation quantification was confirmed. The test was compatible with PGT-A, and half of the embryos tested were shown to be aneuploid (16/33). Mutations were detected in approximately 40% of embryo biopsies from Patients A and D (10/24) but in none from Patients B and C (n = 29). Patients B and C had healthy children following PGT and natural conception, respectively. The m.8993T>G mutation displayed skewed segregation, whereas m.3243A>G mutation levels were relatively low and potentially impacted embryo development.


Conclusions

Considering the high aneuploidy rate, strategies providing a combination of PGT for mtDNA disease and aneuploidy may be advantageous compared with approaches that consider only mtDNA. Heteroplasmic women had a higher incidence of affected embryos than those with undetectable somatic mutant mtDNA but were still able to produce mutation-free embryos. While not conclusive, the results are consistent with the existence of mutation-specific segregation mechanisms occurring during oogenesis and possibly embryogenesis.

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.