Pre-implantation Genetic Testing in Inherited Metabolic Diseases? Stateof- the-art and current challenges

Ana Miguel Capela; Ana Cunha; Ana Maria Fortuna; Cláudia Falcão Reis

doi:10.2174/0118715303279986231211090830

Pre-implantation Genetic Testing in Inherited Metabolic Diseases? Stateof- the-art and current challenges

Endocr Metab Immune Disord Drug Targets. 2023 Dec 18. doi: 10.2174/0118715303279986231211090830. Online ahead of print.

Authors

Ana Miguel Capela¹, Ana Cunha², Ana Maria Fortuna^{1

3}, Cláudia Falcão Reis^{1

3

4

5}

Affiliations

¹ Unidade de Genética Médica, Centro de Genética Médica Jacinto Magalhães - Centro Hospitalar Universitário de Santo António, Portugal.
² Centro de Medicina Fetal (Medicina Fetal Porto) - Centro Materno Infantil do Norte, Centro Hospitalar Universitário de Santo António, Portugal.
³ Unidade Multidisciplinar de Investigação Biomédica, Instituto de Ciências Biomédicas Abel Salazar (UMIB/ICBAS), Universidade do Porto, Porto, Portugal.
⁴ Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.
⁵ ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.

PMID: 38111111
DOI: 10.2174/0118715303279986231211090830

Abstract

Introduction: Inborn errors of metabolism (IEM) are genetic diseases involving congenital disorders of enzyme activities. Most follow Mendelian autosomal recessive inheritance and few follow mitochondrial inheritance. In many cases, after the birth of an affected child parents discover that have been the carriers for the condition and worry about the risk of recurrence in future offspring. Preimplantation genetic testing (PGT) can analyze embryos before their transfer to the uterus and prevent the transmission of hereditary conditions to descendants, however this procedure is of limited value in mtDNA conditions.

Methods: The list of diseases currently approved for PGT were reviewed. The process for eligibility, was as for the Comissão Nacional Procriação Medicamente Assistida (CNPMA), of Portugal (PT). Review of international practices for Assisted Reproductive Techniques (ART) in IEM was carried out.

Results: As of 07.2022, 23 IEM diseases associated with deleterious variants in nDNA were approved for PGT in PT. Couples at risk for conditions not included in the list can solicit an evaluation from an expert committee, after a medical genetics consultation. To qualify for approval, diseases must cause significant suffering and/or premature death. Due to a greater number of solicitations many more IEM conditions have been approved for PGT across the world. ART for mtDNA is not available in PT. International expert centers include PGT for specific well documented variants and mitochondrial donation.

Conclusion: PGT is a reliable approach to reduce the risk of transmission of a genetic condition to the offspring. The list of IEM disorders currently accepted for this technique in Portugal are small, but it is expanding, as many more diseases fit the necessary criteria. While appealing in theory, low success rates coupled with limited availability can be discouraging for patients. Genetic counselling is of paramount importance after the diagnosis of IEM diseases. It is important for both clinicians and patients to be made aware of the available reproductive options and their limitations.

Keywords: Assisted Reproductive Techniques (ART); Genetic counselling; Inborn errors of metabolism (IEM); Preimplantation genetic testing (PGT); mtDNA.