A healthy live birth after mosaic blastocyst transfer in preimplantation genetic testing for GATA1-related cytopenia combined with HLA matching

Abstract

Background: GATA1-related cytopenia (GRC) is characterized by thrombocytopaenia and/or anaemia ranging from mild to severe. Haematopoietic stem cell transplantation (HSCT) is a healing therapeutic choice for GRC patients. We identified a novel pathogenic variant (GATA1: c.1019delG) in a boy with GATA1-related cytopenia. Then we performed preimplantation genetic testing (PGT) in this GRC family. After a mosaic embryo transfered, a healthy and HLA-compatible with the proband baby was delivered.

Case presentation: The proband is a 6-year-old boy who was diagnosed to have transfusion-dependent anaemia since 3 year old. Whole-exome sequencing (WES) showed that the proband has a hemizygous variant c.1019delG in GATA1, which is inherited from his mother. His parents decided to undergo PGT to have a health and HLA-compatible offspring. After whole genome amplification (WGA) of biopsied trophectoderm (TE) cells, next generation sequencing (NGS)-based PGT was preformed to analyse embryos on chromosomal aneuploidy, target mutation and HLA typing. There were 3 embryos HLA-matched to the proband. The genotypes of the 3 embryos were heterozygous variant, hemizygous variant, normal respectively. After a heterozygous, mosaic partial trisomy (chr)16, and HLA-matched embryo transfer, a healthy baby was delivered and whose HSCT is compatible with the proband.

Conclusions: NGS-based PGT-HLA is a valuable procedure for the treatment of GATA1-related cytopenia caused by GATA1 variants, or other haematological disorders, oncological and immunological diseases. Furthermore, our study reconfirms that mosaic embryos transfer would bring healthy offspring.

Keywords: GATA1; HLA typing; Mosaic blastocyst transfer; PGT-M.

Fig. 1

Sanger sequencing results of the GATA1 variant c.1019delG. The proband is hemizygous for the variant. The mother was found to be heterozygous for the variant while the father was normal. K: keto (G or T); S: strong (G or C); W: weak (A or T); Y: pyrimidine (T or C)

Fig. 2

The PGT-M results of GATA1: c.1019delG. A Sanger sequencing result of the 6 blastocysts. K: keto (G or T); M: amino (A or C); R: purine (G or A); S: strong (G or C); W: weak (A or T). B Schematic diagram representing the SNP-based haplotype analysis of the family members and embryos of GATA1. Among the 6 embryos, one blastocyst carried a heterozygous variant, three carried hemizygous variant, while the rest two were unaffected. The SNP ID numbers highlighted in dark blue and orange refer to the upstream and downstream informative SNPs, respectively. The dark blue and the dark orange bars represent the normal haplotype of the father and the mother, respectively. The slashes filled orange bar denotes the variant haplotype of the mother. A 0/0 in the haplotype means unsuccessful genotyping for the marker in that sample. C Prenatal diagnosis of amniotic fluid DNA. Sanger sequencing showed that the newborn baby was unaffected for GATA1 gene

Fig. 3

CNV analyses and SNP-based haplotype analyses results of the family members and embryos of HLA. A CNV analyses results of the embryos. B The SNP-based haplotype linkage analyses of HLA. All the embryos were identified with chromosomal normality except embryo E1 which is mosaic partial trisomy (chr) 16. And there were 3 embryos HLA-matched with the proband. The dark blue and the dark orange bars represent the proband-HLA-unmatched haplotype of the father and the mother, respectively. The slashes filled orange bar denotes the proband-HLA-matched haplotype of the mother, and the backslashes filled light blue bar denotes the proband-HLA-matched haplotype of the father. Color keys of the upstream and downstream informative SNPs of the five HLA gene regions (HLA-A, HLA-B, HLA-C, HLA-DR and HLA-DQ) were showed in the figure legend on the right. A 0/0 in the haplotype means unsuccessful genotyping for the marker in that sample