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Spontaneous abortion occurs in 8-20% of recognized pregnancies and usually takes place in the first trimester (7-11 weeks). There are many causes of pregnancy loss, but the most important (about 75%) is the presence of chromosomal aberrations. We present the results of oligonucleotide array application in a cohort of 62 miscarriage cases. The inclusion criteria for the study were the loss after 8th week of pregnancy and the appearance of recurrent miscarriages. DNA was extracted from trophoblast or fetal skin fibroblasts. In the 62 tested materials from recurrent miscarriages, the detection rate was 56.5% (35/62). The most commonly found were aneuploidies (65%) (chromosomal trisomy 14, 16, 18, 21, and 22), Turner syndrome, and triploidy (17.1%). Other chromosomal abnormalities included pathogenic and likely pathogenic structural aberrations: 1) pathogenic: deletion 7p22.3p12.3 and duplication 9p24.3p13.2 inherited from the normal father, deletion 3q13.31q22.2 and deletion 3q22.3q23 of unknown inheritance and duplication of 17p12 inherited from father with foot malformation; 2) likely pathogenic variants: deletion 17p13.1 inherited from normal mother, deletion 5q14.3 of unknown inheritance and de novo deletion 1q21.1q21.2. Among these aberrations, six CNVs (copy number variants) were responsible for the miscarriage: deletion 7p22.3p12.3 and duplication 9p24.3p13.2, deletion 3q13.31q22.2 and deletion 3q22.3q23, and deletion 17p13.1 and deletion 1q21.1q21.2. Other two findings were classified as incidental findings (deletion 5q14.3 and 17p12 duplication). Our research shows that 17% of the aberrations (6/35 abnormal results) that cannot be identified by the routine kariotype analysis are structural aberrations containing genes important for fetal development, the mutations of which may cause spontaneous abortion., (© 2022. The Author(s).)

Background: Balanced reciprocal chromosomal translocations (RCTs) are the ones of the most common structural aberrations in the population, with an incidence of 1:625. RCT carriers usually do not demonstrate changes in phenotype, except when the translocation results in gene interruption. However, these people are at risk of production of unbalanced gametes during meiosis, as a result of various forms of chromosome segregation. This may cause infertility, non-implantation of the embryo, shorter embryo or foetus survival, as well as congenital defects and developmental disorders in children after birth. The increasing popularity of cytogenetic molecular techniques, such as microarray-based CGH (aCGH), contributed to the improved detection of chromosomal abnormalities in patients with intellectual disability, however, these modern techniques do not allow the identification of the balanced in potential carriers. Therefore, classical chromosome analysis with GTG technique still plays an important role in the identification of balanced rearrangements in every case of procreation failure., Case Presentation: In this article, a family with multiple occurrences of 17p13.3 duplication syndrome in the offspring and multiple miscarriages resulting from carrying of the balanced reciprocal translocation t(7;17)(p22;p13.2) by proband father is presented. The aCGH diagnostics allowed the identification of an unbalanced fragment responsible for the occurrence of clinical signs in the female patient, while karyotyping and FISH using specific probes allowed the localization of the additional material in the patient chromosomes, and identified the type of this translocation in the carriers., Conclusions: Identification of a balanced structural aberration in one of the partners allows direct diagnostics for the exclusion or confirmation of genetic imbalance in the foetus via traditional invasive prenatal diagnostics. It is also possible to use an alternative method, Preimplantation Genetic Diagnosis (PGD) after in vitro fertilization, which prevents initiating pregnancy if genetic imbalance is detected in the embryo.