ABSTRACT

Title: Preimplantation Genetic Testing - Monogenic disorders (PGTM) for sickle cell anaemia prevention

Authors: Wada Aisha¹, Danga Christopher¹, Amatu Tamarapreye¹, Monday Solomon², Wada Ibrahim^1,2

draisha@cellgenomics.com.ng. +234-908-779-8262

1.              Cell Genomics Ltd, Abuja.

2.              Nisa Premier Hospital, Abuja.

Objectives: The breakthrough birth of an unaffected offspring via PGT-M¹ has brought hope to carriers of sickle cell anaemia (SCA). The wider implications of this technology in a low-resource setting need assessment.The objective of this study was to assess the prevalence of SCA in embryos of carrier couples, pregnancy outcomes and technical complications.

Design: This was a retrospective cross-sectional study of 201 embryos from 40 couples, tested for the presence of the HBB c.20A>T p.Glu6Val haemoglobin gene variant (HbS) using PGT-M from 2014-2021.

Method: All embryos tested within the stated time frame were included in the study. From 2018, analysis was carried out at Cell Genomics Laboratory in Abuja and prior to this at Reprogenetics Laboratory in the UK. Cells were processed using the Illumina DNA extraction kit and the PGT-M protocol of Applied Biosystems, then analyzed using the Genetic Analyzer 3500 Series which operates with Sanger sequencing methodology. Genotype report was interpreted as unaffected [normal (HbAA) or carrier (HbAS)], and affected (HbSS).

Mean maternal age was 31.48 (23-41). 101 embryos (50.2%) were unaffected (45 normal (22.39%), 56 carriers (27.86%)) and 62 were affected (30.85%). For 38 embryos, no result was obtained. Between 2018 and 2022, 27 patients had embryo transfers with 4 awaiting frozen embryo transfer. There were 13 pregnancies (43.8%), with 3 ongoing, and 8 live births, all of whom are confirmed to be unaffected.

Conclusion: PGT-M is a viable option for couples who are both carriers of HbS to prevent transmission of sickle cell disease to their offspring.

Keywords: PGT, genetics, sickle-cell anaemia

¹ Ibrahim W, Christopher D, Mohamed C. Live birth following preimplantation genetic testing to prevent sickle cell disease in a low resource setting: A case report. Afr J Reprod Health. 2020 Dec;24(4):218-220. doi: 10.29063/ajrh2020/v24i4.22. PMID: 34077086.