Pre-implantation genetic diagnosis for a family with Usher syndrome through targeted sequencing and haplotype analysis

Objective Our objective was to investigate the applicability of targeted capture massively parallel sequencing in developing personalized pre-implantation genetic diagnosis (PGD) assay. Methods One couple at risk of transmitting Usher Syndrome to their offspring was recruited to this study. The genomics DNA (gDNA) was extracted from the peripheral blood and underwent in vitro fertilization (IVF)-PGD. Prenatal molecular diagnosis was performed in the 20th week of gestation and the chromosomal anomaly was analyzed. Results Customized capture probe targeted at USH2A gene and 350kb flanking region were designed for PGD. Eleven blastocysts were biopsied and amplified by using multiple displacement amplification (MDA) and capture sequencing. A HMM-based haplotype analysis was performed to deduce embryo’s genotype by using SNPs identified in each sample. Four embryos were diagnosed as free of father’s rare mutation, two were transferred and one achieved a successful pregnancy. The fetal genotype was confirmed by Sanger sequencing of fetal genomic DNA obtained by amniocentesis. The PGD and prenatal diagnosis results were further confirmed by the molecular diagnosis of the baby’s genomic DNA sample. The auditory test showed that the hearing was normal. Conclusion Targeted capture massively parallel sequencing (MPS) is an effective and convenient strategy to develop customized PGD assay. Key points Genetic counseling session was conducted with a family having Usher patient who was molecularly diagnosed, and a healthy baby was born with the help of successful PGD assay. This is of vast importance in management plans since it is the first report of PGD in Usher syndrome based on targeted capture MPS.