35. THE APPLICATION OF PGT-A FOR CARRIERS OF BALANCED STRUCTURAL CHROMOSOMAL REARRANGEMENTS

Abstract

Introduction The frequency of chromosomal aberrations account for approximately 15% of the major congenital anomalies diagnosed before the age of 1 year in Europe, and are associated with 25% of perinatal deaths due to congenital anomalies. Balanced rearrangements represent one of the most common forms of genetic abnormality, affecting approximately 1 in every 500 (0.2%) individuals. Difficulties processing the abnormal chromosomes during meiosis lead to an elevated risk of chromosomally abnormal gametes, resulting in high rates of miscarriage and/or children with congenital abnormalities. Unbalanced chromosomal rearrangements in embryos may occur as new event, or is the product of balanced chromosomal rearrangements in one of the parents. PGT-A is one of the choices to exclude embryos with unbalanced translocation and get successful pregnancy. Materials & methods Nine couples, in which one of the partners was carrier of balanced chromosomal rearrangement, were chosen for analysis. Chromosomal rearrangements were confirmed using classical G band cytogenetic approach. IVF was made by adjusting the individual characteristics for each couple. Trophectoderm biopsy was done on day 5. PGT-A was done using aCGH Illumina 24Sure arrays or using NGS – Illumina VeriSeq PGS kit. Analysis was done using BlueFuse for both approaches. Results From nine couples, in three couples male was carrier of Robertsonian translocation 45,XY,der(13;14)(q10;q10). Different balanced reciprocal translocations were observed in remained six couples, from them four were female carriers and two male carriers. Overall, 90 blastocysts from 9 couples were obtained and biopsied. From those 48 blastocysts underwent PGT-A. Results are shown in table: Two successful clinical pregnancies were obtained after FET with euploid embryos. Conclusions Unbalanced translocation rate is higher in reciprocal translocation carriers than Robertsonian translocations carriers. Overall unbalanced translocation rate in embryos is same as sporadic aneuploidy rate, but in case of Robertsonian translocation sporadic aneuploidy rate is much higher than in case of reciprocal translocation, which only partially could be explained by age of women in couple.