Genetic diagnosis of β-thalassemia preimplantation using short tandem repeats in human cryopreserved blastocysts.

This study aimed to evaluate the application of short tandem repeats (STRs) for the preimplantation genetic diagnosis (PGD) of β-thalassemia. This was a prospective study performed at the Liuzhou Maternity and Child Healthcare Hospital. From May to December 2016, eight couples formed of two β-thalassemia carriers underwent in vitro fertilization (IVF) procedures and PGD. All couples and four family members/couple underwent blood testing. Whole genome amplification of trophectoderm cells was performed. PCR products were used for linkage analysis of 15 STR loci. From the eight couples, 147 embryos were obtained and 86 blastocysts were formed. The DNA from 82 blastocysts was successfully amplified (amplification efficiency of 95.4%). Eighty blastocysts obtained a definite diagnosis. Among them, 24 blastocysts were diagnosed as normal, 38 blastocysts were diagnosed as heterozygous for β-thalassemia, and 18 blastocysts were homozygous or compound heterozygous. Two patients received a thawed embryo and both had a clinical pregnancy. These results indicated that in the setting of PGD for β-thalassemia, after multiple displacement amplifications, reverse dot hybridization combined with STRs could be an effective, accurate, and practical clinical strategy to improve the detection of β-thalassemia in at-risk couples undergoing embryo transfer. These results have to be validated in a larger cohort.