Combined Preimplantation Genetic Testing for Genetic Kidney Disease: Genetic Risk Identification, Assisted Reproductive Cycle, and Pregnancy Outcome Analysis

A Strategy Potentially Suitable for Combined Preimplantation Genetic Testing of Aneuploidy and Monogenic Disease That Permits Direct Detection of Pathogenic Variants Including Repeat Expansions and Gene Deletions

Combined preimplantation genetic testing of aneuploidy (PGT-A) and monogenic disease (PGT-M) can be achieved through PCR-based whole genome amplification (WGA) and next-generation sequencing (NGS). However, pathogenic variant detection is usually achieved indirectly through single nucleotide polymorphism haplotyping, as direct detection of pathogenic variants is not always possible. We evaluated whether isothermal WGA was suitable for combined PGT-A and PGT-M that also permitted direct detection of repeat expansions and large deletions, in addition to indirect linkage analysis using microsatellite markers. Five-cell replicates from selected cell lines were subjected to isothermal or PCR-based WGA, followed by NGS-based PGT-A and direct and indirect PGT-M of Huntington's disease and spinal muscular atrophy. Both WGA methods accurately detected aneuploidy and large (10 Mb) segmental imbalances. However, isothermal WGA produced higher genotyping accuracy compared with PCR-based WGA for all analysed microsatellite markers (93.5% vs. 75.6%), as well as at the HTT CAG repeat locus (100% vs. 7.7%) and the SMN1/2 locus (100% vs. 71.8%). These results demonstrate that isothermal WGA is potentially ideal for combined PGT-A and PGT-M that permits both direct and indirect detection of pathogenic variants including repeat expansions and gene deletions.

Preimplantation genetic testing for monogenic disorders (PGT-M) for monogenic nephropathy: a single-center retrospective cohort analysis

Background

Hereditary nephropathy is an important cause of renal insufficiency and end-stage renal disease. Therefore, for couples with monogenic nephropathy, preventing transmission of the disease to offspring is urgent. Preimplantation genetic testing for monogenic disorders (PGT-M) is a means to prevent intergenerational inheritance by screening and transplanting normal embryos. We provide a clinical overview of patients with monogenic nephropathy who underwent PGT-M.

Methods

The single-center retrospective cohort study was conducted at the Center for Reproductive Medicine, Shandong University from January 2014 to December 2022. A total of 352 couples with nephropathy-related disease were included in the cohort totally.

Results

Of the 352 couples with nephropathy-related disease, 180 accepted genetic screening. A total of 104 couples with monogenic nephropathy indications underwent PGT-M, including 90 of autosomal dominant inheritance, 10 of autosomal recessive inheritance, 4 of X-linked inheritance. 498 blastocysts were biopsied prior to testing, and 394 embryos underwent genetic testing, of which 76 were transferable, 247 were non-transferable and 71 were recommended for genetic counseling. Finally, 80 vitrified-thawed single blastocyst transfer cycles were performed in the cohort. Live births occurred in 38 women, of which 37 transferred embryos with non-pathogenic genotypes. The invasive prenatal diagnosis results of 18 women with live birth were obtained through follow-up, consistent with the PGT-M results of transferred embryos.

Conclusions

PGT-M is an effective means of preventing intergenerational inheritance of monogenic nephropathy. The absence of genetic abnormalities detected by prenatal diagnosis in healthy newborns without monogenic nephropathy also underscore its validity.

Preimplantation genetic testing for monogenic disorders (PGT-M) offers an alternative strategy to prevent children from being born with hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes: a retrospective study

BACKGROUND

Preimplantation genetic testing for monogenic disorders (PGT-M) is now widely used as an effective strategy to prevent various monogenic or chromosomal diseases.

MATERIAL AND METHODS

In this retrospective study, couples with a family history of hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes and/or carrying the pathogenic genes underwent PGT-M to prevent children from inheriting disease-causing gene mutations from their parents and developing known genetic diseases. After PGT-M, unaffected (i.e., normal) embryos after genetic detection were transferred into the uterus of their corresponding mothers.

RESULTS

A total of 43 carrier couples with the following hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes underwent PGT-M: Duchenne muscular dystrophy (13 families); methylmalonic acidemia (7 families); spinal muscular atrophy (5 families); infantile neuroaxonal dystrophy and intellectual developmental disorder (3 families each); Cockayne syndrome (2 families); Menkes disease, spinocerebellar ataxia, glycine encephalopathy with epilepsy, Charcot-Marie-Tooth disease, mucopolysaccharidosis, Aicardi-Goutieres syndrome, adrenoleukodystrophy, phenylketonuria, amyotrophic lateral sclerosis, and Dravet syndrome (1 family each). After 53 PGT-M cycles, the final transferable embryo rate was 12.45%, the clinical pregnancy rate was 74.19%, and the live birth rate was 89.47%; a total of 18 unaffected (i.e., healthy) children were born to these families.

CONCLUSIONS

This study highlights the importance of PGT-M in preventing children born with hereditary neurological diseases or metabolic diseases dominated by nervous system phenotypes.

State of the Science and Ethical Considerations for Preimplantation Genetic Testing for Monogenic Cystic Kidney Diseases and Ciliopathies

There is a broad phenotypic spectrum of monogenic polycystic kidney diseases (PKDs). These disorders often involve cilia-related genes and lead to the development of fluid-filled cysts and eventual kidney function decline and failure. Preimplantation genetic testing for monogenic (PGT-M) disorders has moved into the clinical realm. It allows prospective parents to avoid passing on heritable diseases to their children, including monogenic PKD. The PGT-M process involves embryo generation through in vitro fertilization, with subsequent testing of embryos and selective transfer of those that do not harbor the specific disease-causing variant(s). There is a growing body of literature supporting the success of PGT-M for autosomal-dominant and autosomal-recessive PKD, although with important technical limitations in some cases. This technology can be applied to many other types of monogenic PKD and ciliopathies despite the lack of existing reports in the literature. PGT-M for monogenic PKD, like other forms of assisted reproductive technology, raises important ethical questions. When considering PGT-M for kidney diseases, as well as the potential to avoid disease in future generations, there are regulatory and ethical considerations. These include limited government regulation and unstandardized consent processes, potential technical errors, high cost and equity concerns, risks associated with pregnancy for mothers with kidney disease, and the impact on all involved in the process, including the children who were made possible with this technology.