Autosomal Reciprocal Translocations

2018 ◽  
Author(s):  
R. J McKinlay Gardner ◽  
David J Amor
Keyword(s):  
Practical Problem ◽  
Segment Length ◽  
Balanced Translocation ◽  
Reciprocal Translocations ◽  
Phenotypic Abnormality ◽  
Genetic Risks

This chapter reviews in detail the question of carriers of autosomal reciprocal translocations and the genetic risks implied for potential offspring of theirs. Examples are offered of the various possibilities due to malsegregation in gametes of theirs: adjacent-1, adjacent-2, 3:1, and the (very rare) 4:0 malsegregation. The chapter provides advice on determining the most likely modes of segregation, according to the different forms of translocation (length of centric segment, length of translocated segment, sizes of derivative chromosomes). The chapter discusses the practical problem of the apparently balanced translocation but which is associated with phenotypic abnormality. Associations with infertility are noted.

scholarly journals Diagnosis of De Novo Mosaic Balanced Translocation t(1;3)(q42;q25) in a Fetus Conceived Using Pre-implantation Diagnosis Due to Presence in the Father of a Different Balanced Translocation

2021 ◽  
Author(s):  
Shaoqin Zhang ◽  
jianjiang zhu ◽  
Hong Qi ◽  
Limei Xu ◽  
Lirong Cai ◽  
...  
Keyword(s):  
Reciprocal Translocation ◽  
De Novo ◽  
Psychomotor Development ◽  
Premature Delivery ◽  
Driving Mechanism ◽  
Balanced Translocation ◽  
Translocation Carrier ◽  
Reciprocal Translocations ◽  
Str Analysis

Abstract IntroductionPreimplantation genetic testing (PGT) had widely been applied in reciprocal translocation carriers to improve the clinical outcome of assisted reproduction. De novo mosaicism balanced reciprocal translocations in fetus conceived using PGT from a balanced translocation carrier parent has been rarely reported, and the driving mechanism is not clearly. MethodsChromosomal microarray analysis (CMA) , karyotype analysis and fluorescent in situ hybridization (FISH) were performed to verify the type and heredity of the rearrangement. STR analysis was used to identify potential contamination as well as kinship verification and identification. ResultsA rare de novo mosaicism balanced reciprocal translocation t(1,3)(q42;q25) in fetus conceived using PGT-SR from a t(12;14)(q22;q13) balanced translocation carrier father was been diagnosed by multiplatform genetic techniques. At 31 weeks and 2 days of gestation, premature delivery was caused by uncontrollable uterine contractions. At the 21-months follow up, infant has achieved all psychomotor development milestones as well as growth within the normal reference range. ConclusionPGT cases still need close observation in prenatal diagnosis and long-term follow-up.

Autosomal Ring Chromosomes

2018 ◽  
Author(s):  
R. J McKinlay Gardner ◽  
David J Amor
Keyword(s):  
Ring Chromosome ◽  
Chromosome Count ◽  
Small Ring ◽  
Intellectual Deficiency ◽  
Relevant Issue ◽  
Ring Chromosomes ◽  
Phenotypic Abnormality ◽  
Genetic Risks ◽  
Additional Chromosome ◽  
End To End

Ring chromosomes are uncommon. The typical physical phenotype comprises major dysmorphogenesis and intellectual deficiency, and reproduction is not usually a relevant issue. A ring chromosome is formed due to an end-to-end fusion of chromosome tips. Almost always, the end result is an imbalance and significant phenotypic abnormality. Rarely, however, this is not the case. In this chapter, genetic risks for ring carriers for whom procreation is a realistic likelihood are considered. This chapter distinguishes between those with a normal 46 chromosome count, one being a ring, and those with a 47 chromosome count, the additional chromosome being a (necessarily small) ring.

scholarly journals De novo balanced reciprocal translocation mosaic t(1;3)(q42;q25) detected by prenatal genetic diagnosis: a fetus conceived using preimplantation genetic testing due to a t(12;14)(q22;q13) balanced paternal reciprocal translocation

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Shaoqin Zhang ◽  
Jianjiang Zhu ◽  
Hong Qi ◽  
Limei Xu ◽  
Lirong Cai ◽  
...  
Keyword(s):  
Genetic Testing ◽  
Reciprocal Translocation ◽  
De Novo ◽  
Psychomotor Development ◽  
Chromosomal Microarray Analysis ◽  
Driving Mechanism ◽  
Balanced Translocation ◽  
Translocation Carrier ◽  
Preimplantation Genetic Testing ◽  
Reciprocal Translocations

Abstract Introduction De novo balanced reciprocal translocations mosaicism in fetus conceived using preimplantation genetic testing from a different balanced translocation carrier parent has been rarely reported. Methods Chromosomal microarray analysis, karyotype analysis and fluorescent in situ hybridization were performed to verify the type and heredity of the rearrangement. STR analysis was conducted to identify potential contamination and verify kinship. In addition, a local BLAST engine was performed to locate potentially homologous segments which might contribute to the translocation in breakpoints of chromosome. Results A rare de novo balanced reciprocal translocations mosaicism mos 46,XY,t(1;3)(q42;q25)[40]/46,XY[39] was diagnosed in a fetus conceived using preimplantation genetic testing due to a 46,XY,t(12;14)(q22;q13) balanced translocation carrier father through multiplatform genetic techniques. Two of the largest continuous high homology segments were identified in chromosomal band 1q42.12 and 3q25.2. At the 21-months follow up, infant has achieved all psychomotor development milestones as well as growth within the normal reference range. Conclusion We present a prenatal diagnosis of a rare de novo balanced reciprocal translocations mosaicism in a fetus who conceived by preimplantation genetic testing. The most reasonable driving mechanism was that a de novo mitotic error caused by nonallelic homologous recombination between 1q42.12 and 3q25.2 in a zygote within the first or early cell divisions, which results in a mosaic embryo with the variant present in a half proportion of cells.

O-063 PGT-M, for multi-system genetic diseases

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
J Xu
Keyword(s):  
Chromosomal Abnormalities ◽  
Genetic Diseases ◽  
Genetic Diagnosis ◽  
Disease Patient ◽  
Carrier Status ◽  
Balanced Translocation ◽  
Reciprocal Translocations ◽  
Monogenic Disorders ◽  
Pathogenic Genes ◽  
Registration Number

Abstract Abstract text Reciprocal translocations (RecT) and Robertsonian translocations (RobT) are among the most common chromosomal abnormalities that cause infertility and birth defects. In 2017, the Reproductive Medicine Center of the first affiliated Hospital of Zhengzhou University reported a method named "Mapping Allele with Resolved Carrier Status" (MaReCs), which enables chromosomal ploidy screening and resolution of the translocation carrier status of the same embryo. Meanwhile, the first international healthy baby, where the chromosomal balanced translocation that can be transmitted to offspring was precisely blocked by ''MaReCS, was born in our center''. Roche translocation can also delivery healthy babies. Therefore, MaReCs accurately enables the selection of translocation-free embryos from patients carrying chromosomal translocations.In addition, with regard to the monogenic disorders and relative cases, our center used Karyomapping-SNP and NGS technology for preimplantation genetic diagnosis, completed the first Huntington's disease patient in China and delivered a healthy embryos. NGS/Karyomapping PGD can be used to assist pregnancy for all genetic diseases with clear genetic patterns and pathogenic genes. Trial registration number: Study funding: Funding source:

O-206 Meiotic segregation analysis for reciprocal translocation carriers: Assessment of factors influencing meiotic segregation patterns

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
P Xie ◽  
H Liang ◽  
P Yangqin ◽  
T Yueqiu ◽  
L Ge
Keyword(s):  
Risk Factors ◽  
Reciprocal Translocation ◽  
Protective Factor ◽  
Snp Array ◽  
Female Gender ◽  
Meiotic Segregation ◽  
Balanced Translocation ◽  
Reciprocal Translocations ◽  
Chromosome Arm ◽  
Independent Risk Factors

Abstract Study question To analyze factors that could influence meiotic segregation patterns for reciprocal translocation carriers. Summary answer Involvement of an Acr-ch, female gender, and lower TAR1 (ratio of translocated segment 1 over the chromosome arm) were independent risk factors for alternate segregation. What is known already Reciprocal translocation is one of the more common structural rearrangements of chromosomes, which is associated with reproductive risks, such as infertility, spontaneous abortion and the delivery of babies with mental retardation or developmental delay. Extensive studies on meiotic segregation patterns of sperm, blastomere, and blastocysts have identified several factors that may influence the generation of unbalanced rearrangement of reciprocal translocations, including carrier’s gender and age, location of breakpoints, chromosome type, and the quadrivalent structure. However, some results are controversial. Study design, size, duration A retrospective study from October 2013 to December 2019, a total of 10846 blastocysts originating from 2871 oocyte retrieval cycles from 2253 couples with one of the partners carrying reciprocal were investigated. The mean maternal age was 29.97±4 years (20 –47years). Participants/materials, setting, methods Trophectoderm biopsy of blastocysts was performed on the 5th or 6th day of development. Whole genome amplification (WGA) was performed on all samples, and the WGA was analyzed with SNP array or NGS. Segregation patterns of quadrivalent in 10846 blastocysts were analyzed. Risk factors for segregation patterns were explored through analyzing carriers’ demographic and cytogenetic characteristics using multivariate generalized linear mixed models (GLMMs). Main results and the role of chance The percentage of normal/balanced blastocysts was 34.3%, and 2:2 segregation was observed in 90.0% of blastocysts. Increased TAR1 (the ratio of translocated segment 1 over the chromosome arm) was noted as an independent protective factor for the proportion of alternate segregation (P = 0.004). The female gender and involvement of an Acr-ch were found independent risk factors for alternate segregation (P < 0.001). A higher TAR1 reduced the risk of adjacent-1 segregation; longer translocated segment and female gender increased the risk of adjacent-2 segregation (P = 0.009 and P < 0.001, respectively). Female gender and involvement of an Acr-ch enhanced the risk of 3:1 segregation (P < 0.001 and P = 0.012, respectively). Limitations, reasons for caution About 1400 blastocysts were not diagnosed in the 2871 cycles, which might cause bias in the results. Secondly, the interchromosomal effect of reciprocal translocations was not analyzed in this study. Wider implications of the findings In conclusion, a carrier’s gender, involvement of an Acr-ch, and location of breakpoints may influence the segregation patterns. Besides, involvement of an Acr-ch, female gender, and lower TAR1 are independent risk factors for alternate segregation. These results may provide more appropriate genetic counseling for couples with balanced translocation. Trial registration number no

scholarly journals NATURE AND CONSEQUENCES OF INDUCED CHROMOSOME DAMAGE IN MAMMALS

Genetics ◽  
1974 ◽  
Vol 78 (1) ◽  
pp. 173-186
Author(s):  
A G Searle
Keyword(s):  
Germ Cells ◽  
Primary Spermatocyte ◽  
Break Point ◽  
Complete Separation ◽  
Point Of View ◽  
Centromeric Heterochromatin ◽  
General Tendency ◽  
Male Sterile ◽  
Balanced Translocation ◽  
Reciprocal Translocations

ABSTRACT There are marked qualitative and quantitative differences in the patterns of chromosomal damage observed after irradiation of spermatogonia, spermatozoa and oocytes of mice. These differences often result from reduced or zero transmission of particular classes of abberration arising in pre-meiotic germ cells. Probably this is the reason why the level of X-chromosomal and autosomal monosomy is not increased after spermatogonial irradiation. Similarly, the reduced transmission of certain d-se deficiencies may help to explain their low F1 frequency after pre-meiotic as compared with later irradiation. Spermatozoal irradiation has revealed no Robertsonian translocations, but has produced some types of reciprocal translocations which apparently are not transmitted to the F1 after spermatogonial treatment because they prevent maturation of the male pre-meiotic germ cell. Thus they cause sterility in males, but not in females. They include X-autosome and Y-autosome translocations, those giving a metacentric or sub-metacentric chromosome (with reciprocal product present) and those in which one break-point is in or near the centromeric heterochromatin while the other is more distally placed. This last group (which grades into male sub-fertile conditions) gives a preponderance of chain configurations (often with one separate univalent) in heterozygotes of both sexes at meiosis and a high incidence of somatic marker chromosomes. Nondisjunction associated with the univalent generates tertiary trisomics, which are usually male-sterile also and may show phenotypic abnormalities. Sterile males with complete separation of X and Y chromosomes have also been reported after mutagenic treatment of meiotic and post-meiotic germ cells. Such separation seems to prevent a primary spermatocyte from forming a secondary one. The usual derivation (in mouse and man) of tertiary trisomics from mothers rather than from fathers may be due to a similar block, together with a general tendency for male heterozygotes for the parental balanced translocation to be sterile or sub-fertile. Mature oocytes tend to resemble spermatoza in the types of aberration produced by irradiation, which include the male-sterile translocation, but more data are needed. Many of the aberrations described contribute to the human cytogenetic load and can be studied in the mouse from this point of view.

A case of prenatal diagnosis of an unbalanced karyotype in a fetus with partial trisomy 12q22qter in the first trimester of pregnancy in the family carriers of reciprocal translocations

2018 ◽  
Author(s):  
O.A. Gromyko, E.I. Golovataya, I.V. Novikova
Keyword(s):  
Prenatal Diagnosis ◽  
Partial Trisomy ◽  
First Trimester ◽  
Balanced Translocation ◽  
Reciprocal Translocations ◽  
The Family ◽  
First Trimester Of Pregnancy

A case of prenatal diagnosis of partial trisomy 12q22qter in the first trimester of pregnancy is presented. The unbalanced karyotype of the fetus 46,XX,der(10)t(10;12)(p25;q22)mat was as a result of the mother's carrier balanced translocation. The data of ultrasound, cytogenetic and pathoanatomic studies are presented.

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