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The Genetic Risk of a Couple Aiming to Conceive
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Joe Leigh Simpson, Svetlana Rechitsky, Anver Kuliev
Theoretical risks for a parent with a balanced reciprocal translocation of having unbalanced translocation offspring can be calculated, but more useful are empirical data. Theoretical risks are greater than empirical risks (20), and less clinically applicable. However, empirical data are not always available for a specific reciprocal translocation. Even if the same two chromosomes are involved, even if also the same arms (short arm or long arm), the precise chromosomal breakpoints very likely will differ. Thus, only generalizations are possible, derived from pooled data compiled from different translocations.
Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
One frequent cause of structural alteration is a translocation. There are two basic types of translocations. A reciprocal translocation occurs when two chromosomes break and the pieces exchange places (Fig. 10). The resulting abnormal chromosomes are called “derivative chromosomes.” If the reciprocal translocation is balanced, the individual is usually normal. Translocations such as these are found in approximately 1 in 500 normal individuals in the general population and are usually never detected. However, if a parent carries a balanced translocation and passes only one of his or her derivative chromosomes to an offspring, along with the other normal chromosomes, the child will have an unbalanced chromosome complement and will likely have multiple problems as a result (Fig. 11). Inheritance of a derivative chromosome in this situation causes a partial duplication (partial trisomy) of one chromosome and a partial deletion (partial monosomy) of another chromosome.
Investigations, treatment and management
Published in Janetta Bensouilah, Pregnancy Loss, 2021
More females than males are affected by structural chromosomal abnormalities, and for these to cause RM, one partner must have a chromosomal abnormality or produce recurrent abnormalities in the embryo (e.g. through increasing maternal age). The most common karyotypic abnormality found in parental chromosomal screening is a balanced or reciprocal translocation. Fetal aneuploidy is the most common cause of miscarriage and is mostly related to maternal age. Where screening detects abnormalities, genetic counselling that explores the couple’s individual prognosis should be offered.
Reproductive outcomes in couples with sporadic miscarriage after embryonic chromosomal microarray analysis
Published in Annals of Medicine, 2023
Zhengyi Xia, Ran Zhou, Yiming Li, Lulu Meng, Mingtao Huang, Jianxin Tan, Fengchang Qiao, Hui Zhu, Ping Hu, Qiaoying Zhu, Zhengfeng Xu, Yan Wang
In this study, we observed that couples with partial aneuploid miscarriage (19.0%) showed a significantly higher risk of subsequent spontaneous abortion than couples with chromosomally normal miscarriage (6.5%). It is known that subsequent prognosis in couples carrying a reciprocal translocation (31.9%) was obviously poorer than that in non-carrier couples (71.7%) [18]. Nevertheless, all couples with partial aneuploid miscarriage who had a second abortion in this study were identified as non-carrier couples. Accordingly, we suggest further investigation and treatment for these couples to determine the pathogenesis of a second miscarriage. Additionally, a significantly higher prevalence of ectopic pregnancy was found in couples with microdeletion/microduplication miscarriage (9.1%) than in couples with chromosomally normal miscarriage (0.9%). However, the currently available data are not robust enough to draw a solid conclusion due to a limited number of samples in this subgroup. It remains uncertain whether this finding could reflect the actual condition, and further large-scale research is required to investigate the reproductive outcomes of SM couples with microdeletion/microduplication miscarriage.
Extending Phenotypic Spectrum of 17q22 Microdeletion: Growth Hormone Deficiency
Published in Fetal and Pediatric Pathology, 2021
Ceren Damla Durmaz, Şule Altıner, Elifcan Taşdelen, Halil Gürhan Karabulut, Hatice Ilgın Ruhi
Reciprocal translocation which is one of the structural chromosomal abnormalities occurs approximately in 1 in 500 people [7]. The translocation may have arisen de novo in the person, or it may be inherited. Mostly de novo reciprocal translocations occur in male meiosis. During spermatogenesis, it can be assumed that some cells escape from the mechanism that controls the correct crossing-over, they are exposed to a chaotic fracture, and the broken parts are subjected to exonuclease degradation [8, 9]. Whereas most de novo Robertsonian translocations arise during oogenesis [10]. Cryptic deletions have been reported in approximately 40% of phenotypically abnormal patients with apparently balanced chromosomal abnormalities [8, 11]. Mechanisms of the deletion at the breakpoints are still unclear.
A rare Y-autosome translocation found in a patient with nonobstructive azoospermia: Case report
Published in Systems Biology in Reproductive Medicine, 2021
Anita Barišić, Alena Buretić Tomljanović, Nada Starčević Čizmarević, Saša Ostojić, Pavle Romac, Jadranka Vraneković
In the general population, reciprocal translocations between the Y chromosome and non-acrocentrics, including chromosome 1, are rarely observed. However, they are more common in infertile men (Delobel et al. 1998). Besides, the reported rate of balanced reciprocal translocation in couples with reproductive failure is the highest on chromosome 1 (Wang et al. 2016). This is supported by an analysis of published literature that shows a strong correlation between chromosome 1 translocation carriers and reproductive failure, azoospermia, and male infertility (Bache et al. 2004). The detected translocation of the 1q segment to the Yq may disrupt the process of X–der(Y) and 1-der(1) chromosome pairing, crossing over and segregation, thereby leading to impaired sperm production and degeneration of spermatocytes by apoptosis (Pinho et al. 2005).