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Recurrent Pregnancy Loss
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Reshama S. Navathe, Shabani Ahluwalia
Three to five percent of couples with RPL have one parent with balanced translocation, mosaicism, or, less commonly, a chromosome inversion. Although these couples experience increased reproductive loss rates, most will have successful pregnancies without intervention [19]. Available intervention includes preimplantation genetic screening (PGS) and donor gametes.
Developmental Disorders
Published in Jeremy R. Jass, Understanding Pathology, 2020
Congenital malformations have been known to humankind since the dawn of time. Serious malformations are due to a localised error of structural development occurring in the eight weeks following conception. Milder defects (included in Table 10) develop later. One malformation may lead to another and be caused by genetic factors, by environmental factors or by a combination of the two. The genetic causes are classified into chromosomal and single gene disorders. A chromosomal disorder implies an abnormality that can be visualised by the technique of preparing a chromosome spread from a dividing cell and examining the stained chromosomes under a microscope (karyotyping). Abnormalities may include an extra chromosome (e.g. trisomy 21 causing Down’s syndrome), an absent chromosome (e.g. XO causing Turner’s syndrome), deletion of part of a chromosome, inversion of part of a chromosome or a translocation of one part of a chromosome to another. Chromosomal disorders usually arise during gametogenesis and are generally not transmitted since affected individuals either die at birth or are sterile.
Introductory Remarks
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Chromosomal amplification/repetition refers to the presence of extra piece from another chromosome that leads to multiple copies of all chromosomal regions and increases the dosage of the genes located within. Chromosomal deletion refers to loss of large chromosomal regions including certain genes (with interstitial deletion being defined as an intra-chromosomal deletion that removes a segment of DNA from a single chromosome and thus apposes previously distant genes, and loss of heterozygosity being loss of one allele, either by a deletion or a genetic recombination event, in an organism with two different alleles). Chromosomal translocation refers to interchange of genetic parts from nonhomologous chromosomes, and chromosomal inversion refers to reversion of the orientation of a chromosomal segment [6].
Abnormal chromosomes identification using chromosomal microarray
Published in Journal of Obstetrics and Gynaecology, 2022
Yunfang Shi, Xiaozhou Li, Duan Ju, Yan Li, Xiuling Zhang, Ying Zhang
A 37-year-old primigravida was referred to our centre for cordocentesis due to foetal IUGR and smaller limbs than normal gestational weeks. Her medical history included an abnormal karyotype 46,XX,inv(11)(p15.4q23) and infertility for about 10 years. The pregnancy was achieved via invitro fertilisation. The pregnant woman received routine prenatal care at an outside institution and declined amniocentesis in the second trimester. She chose non-invasive prenatal testing (NIPT), which showed low risk for trisomy 21, 18 and 13. Cordocentesis was carried out at a gestational age of 30 weeks, and foetal karyotype was normal (46,XX). SNP-array result showed a 10.0 Mb deletion in 11q24.2q25 of chromosome 11 containing 41 OMIM genes involved KCNJ1, JAM3 and KIRREL (Figure 3). However, the partial deletion of chromosome 11 was explained by the maternal chromosomal inversion and the couple opted to terminate the pregnancy after genetic counselling.
History of radiation genetics: light and darkness
Published in International Journal of Radiation Biology, 2019
It 1927 Muller first reported that X-ray exposures could increase the frequency of mutations in fruit flies (Muller 1927). In those days, and in fact far beyond the Muller studies, genes were thought to be highly stable and to change only rarely (spontaneous mutations were known), and there was no method to artificially alter gene functions (the fragile nature of the genome was only realized in 1949 when photo-reactivation was discovered: Kelner 1949). The important thing to mention here is not the fact that Muller subjected flies to X-ray exposures, but that he had genetically altered the flies so that the induced mutations could be quantified and transmitted consistently to subsequent generations. Specifically, these studies used a special X chromosome which contained a large inversion. When a female has two normal X chromosomes, meiotic recombination causes an exchange of chromosome segments between the two X chromosomes, and this makes it impossible to determine the origin of mutations that were induced in one X chromosome and to trace the mutations in subsequent generations. In contrast, when the female is heterozygous with an X-chromosome inversion, any single recombination leads to the formation of a dicentric chromosome, and hence cells bearing this are effectively eliminated. If the inversion were more complex (e.g. a second inversion within an inversion), even the probability of a meiotic pairing of homologous chromosomes may be reduced.
Aetiology of recurrent miscarriage and the role of adjuvant treatment in its management: a retrospective cohort review
Published in Journal of Obstetrics and Gynaecology, 2018
Samuel James Alexander Dobson, Kanna Mannadiar Jayaprakasan
26/242 couples had an abnormal miscarriage tissue karyoptype and were subsequently offered testing for parental karyotyping. Overall, 7/242 (2.9%) couples had one partner with a chromosomal abnormality on parental karyotyping. All abnormalities were found to be maternal apart from two; 2/7 (0.83%) patients had mosaic klinefelter, 2/7 (0.83%) had pericentric chromosome inversion, 1/7 (0.41%) had mosaic trisomy 21, 1/7 (0.41%) had mosaic trisomy 8 and 1/7 (0.41%) had a balanced translocation. Within this group all patients received only early support. 6 out of the 7 patients had a further pregnancy, resulting in 3 live births.