Spectrum of Cytogenomic Abnormalities Revealed by Array Comparative Genomic Hybridization on Products of Conception Culture Failure and Normal Karyotype Samples

Approximately 30% of pregnancies after implantation end up in spontaneous abortions, and 50% of them are caused by chromosomal abnormalities. However, the spectrum of genomic copy number variants （CNVs） in products of conception （POC） and the underlying gene- dosage-sensitive mechanisms causing spontaneous abortions remain largely unknown. In this study, array comparative genornic hybridiza- tion （aCGH） analysis was performed as a salvage procedure for 128 POC culture failure （POC-CF） samples and as a supplemental procedure for 106 POC normal karyotype （POC-NK） samples. Chromosomal abnormalities were detected in 10% of POC-CF and pathogenic CNVs were detected in 3.9% of POC-CF and 5.7% of POC-NK samples. Compiled results from this study and relevant case series through a literature review demonstrated an abnormality detection rate （ADR） of 35% for chromosomal abnormalities in POC-CF samples, 3.7% for pathogenic CNVs in POC-CF samples, and 4.6% for pathogenic CNVs in POC-NK samples. Ingenuity Pathway Analysis （IPA） was performed on the genes from pathogenic CNVs found in POC samples. The denoted primary gene networks suggested that apoptosis and cell proliferation pathways are involved in miscarriage. In summary, a similar spectrum of cytogenomic abnormalities was observed in POC culture success and POC-CF samples. A threshold effect correlating the number of dosage-sensitive genes in a chromosome with the observed frequency of autosomai trisomy is proposed. A rationalized approach using firstly fluorescence in situ hybridization （FISH） testing with probes of chromosomes X/Y/ 18, 13/21, and 15/16/22 for common aneuploidies and polyploidies and secondly aCGH for other cytogenomic abnormalities is recommended for POC-CF samples.

Repeated pregnancy losses with multiple aneuploidies and major genomic imbalance:A case report

Rationale:If one of the partners is having balanced autosomal translocation,it is usually observed that the offspring inherit either normal chromosomes,balanced translocation identical to one of the parent or unbalanced chromosomal rearrangements of the same parental chromosome having translocation.Concern:A unique case presented with history of 8 miscarriages for genetic counseling.The last abortus material evaluation showed monosomy of chromosome X(Turner syndrome)in all the analyzed cells.There was a history of infertility and also repeated second trimester abortions on the paternal side.On the maternal side,there was a history of intellectual disability.Diagnose:History of repeated abnormal pregnancy outcomes.Wife’s karyotype is normal;however,husband shows translocation between chromosome 4 and 22.Intervention:Peripheral blood sample around 3 mL was collected for karyotype.Embryo biopsy was done and DNA was extracted and processed for whole exome sequencing.Outcomes:Wife’s karyotype is normal and husband has translocation between chromosome 4 and 22.Surprisingly,the entire pregnancy outcome including embryo screening has different,complete or partial aneuploidies of chromosomes other than chromosome 4 and 22.Main lesson:Though the translocation in one of the parent is balanced,we have to think beyond traditional ways for evaluating a couple with repeated pregnancy loss as we cannot predict the errors at cell division.Option of in vitro fertilization and preimplantation genetic diagnosis in couples having balanced translocations should be discussed so that early intervention can prevent the agony of pregnancy loss.