Preimplantation genetic testing for inborn errors of metabolism: observations from a reproductive genetic laboratory in China.

In this study, we aimed to apply preimplantation genetic testing for monogenic disorders (PGT-M) based on mutated allele revealed by sequencing with aneuploidy and linkage analyses (MARSALA) to block the transmission of inborn errors of metabolism (IEMs). After the disease-causing variants were identified through genetic testing, four carrier couples having children affected with IEMs, including methylmalonic aciduria, glutaric acidemia type 1, beta-ketothiolase deficiency, and ornithine transcarbamylase deficiency, sought PGT-M. A series of PGT procedures involving intracytoplasmic sperm injection, blastocyst culture, biopsy of trophectoderm cells, and next-generation sequencing (NGS)-based MARSALA, was performed to provide comprehensive chromosome screening and variant gene analysis. Finally, embryos were selected for transfer, and prenatal diagnosis was conducted to confirm the PGT-M results. All four carrier couples obtained transferrable embryos after PGT. The results of the prenatal diagnosis were consistent with the PGT results, and all couples gave birth to healthy babies free of IEMs. The results of this study confirm that NGS-based MARSALA is an effective approach for families with IEMs to prevent the subsequent transmission of pathological genetic variants to the next generation.