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Prenatal Diagnosis and Screening for Aneuploidy
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Sarah Harris, Angie Jelin, Neeta Vora
Fluorescent in situ hybridization (FISH) allows for the rapid and accurate detection of trisomies 21, 18, and 13, as well as sex chromosome aneuploidy and triploidy. These common aneuploidies account for 80% of clinically significant chromosome conditions detected prenatally [46]. In the event of an abnormal FISH result, confirmatory testing should be completed using a conventional karyotype to determine if a chromosomal translocation is present. If FISH results are normal, then additional testing with conventional karyotype or chromosomal microarray (CMA) analysis should be considered to rule out less common aneuploidies or to identify smaller deletions or duplications that would be missed using FISH alone.
Renal Cancer
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Sabrina H. Rossi, Grant D. Stewart
Gene translocations involving MiT family of transcription factor genes (e.g., genes TFE3 and TFEB).Translocation: gene rearrangement and fusion between non-homologous chromosomes.Fluorescent in situ hybridisation (FISH) may be used to demonstrate chromosomal translocation and determine diagnosis.
Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
The second type of screening includes testing of targeted ethnic or racial populations to identify carriers of genetic disease. Examples are cystic fibrosis in Caucasians, Tay–Sachs disease in Ashkenazi Jews, and hemoglobinopathies in African-Americans (10). On a smaller scale, genetic screening can involve karyotype analysis on family members at risk for having a chromosome translocation. Carrier testing is also available for women who are at risk to be carriers for X-linked disorders such as Duchenne muscular dystrophy or Fragile X syndrome. This type of population screening will not affect the health of the carrier, but will have a significant impact on reproductive choices for the family. It is essential that appropriate genetic counseling accompany the information given regarding carrier status.
Genetic variations as molecular diagnostic factors for idiopathic male infertility: current knowledge and future perspectives
Published in Expert Review of Molecular Diagnostics, 2021
Mohammad Karimian, Leila Parvaresh, Mohaddeseh Behjati
Balanced chromosomal translocations involve the breakage of two chromosomes and abnormal repair of chromosomal fragments resulting in the transfer of genetic material from one chromosome to another without loss of any genetic material. In vast majority of cases, carriers of balanced translocations are phenotypically normal, unless one of the breakpoints at the site of translocation disrupts an important gene. Chromosomal translocation, while phenotypically normal, may experience fertility loss, miscarriage, or birth defects. Normal meiotic segregation of these translocations in gametes can lead to duplication or deletion of chromosomal regions involved in translocation [171]. Like chromosomal translocations, inversions can lead to infertility, miscarriage, and birth defects. During meiosis, chromosomes are forced to form specialized structures, so that homologous chromosomes can be paired. Chromosomal inversions can affect these specialized structures. Research on the production of unbalanced gametes in balanced inversion carriers has been done to a much lesser extent than translocations. However, a handful of studies have reported an unbalanced sperm range of 1–54% [172–174].
Cytogenetic and molecular genetic methods for chromosomal translocations detection with reference to the KMT2A/MLL gene
Published in Critical Reviews in Clinical Laboratory Sciences, 2021
Nikolai Lomov, Elena Zerkalenkova, Svetlana Lebedeva, Vladimir Viushkov, Mikhail A. Rubtsov
This review summarizes the current methods for detection of chromosomal translocations, with KMT2A-associated AL as an example. These methods differ in their applicability, required time, and cost (Table 1). Routine clinical diagnosis of AL is usually limited to karyotyping and FISH with a standard set of probes (e.g. KMT2A BA probes) and provides only gross information regarding chromosomal abnormalities and the presence of well-known chromosomal translocations. Routine karyotyping can be complemented by more informative, multicolor FISH methods: M-BAND, M-FISH, and SKY. These methods are suitable for the identification of complex chromosomal rearrangements and have better resolution than conventional karyotyping. More profound analysis, including determination of the translocation partner locus and the exact location of a breakpoint, is essential, as it influences the estimation of prognosis and selection of therapy protocols. To this aim, PCR-based approaches, such as LDI-PCR or NGS, may be the methods of choice. These methods allow the identification of new partner genes that have not been previously observed in translocations. Due to the high heterogeneity of KMT2A-rearrangements, a whole variety of methods should be applied. A representative scheme of chromosomal translocation detection integrating all mentioned methods is shown in Figure 8.
CGH Array and Karyotype as Complementary Tools in Prenatal Diagnosis: Prenatal Diagnosis of a 4q Derivative Chromosome from Maternal 4q;11q Translocation
Published in Fetal and Pediatric Pathology, 2018
Cristina Gonzalez, Miriam Gutierrez Serrano, Carmen Barbancho Lopez, Taida Garcia-Riaño, Vanesa Barea Calero, Rebeca Moreno Perea, Begoña Rodriguez Mogollón, Amelia Queipo Rojas, Ana Garcia Climent, Fernando Cava Valenciano
Karyotyping permits a reliable study of all chromosomic structural alteration, such as inversion, balanced translocation, triploidies and low mosaicism that CMA cannot detect. Furthermore, karyotyping helps to characterize CMA findings like derivative chromosome or extra marker chromosomes, which are essential for helping to understand the mechanism of the alteration, and to facilitate the familiar genetic counseling for futures pregnancies. CMA is faster than karyotyping, and this technique can be the first diagnostic step until we obtain the karyotype results approximately one week later. Once we apply a sampling technique that implies a risk for abortion, it is worth performing all needed techniques to obtain the most comprehensive diagnosis. To undertake techniques simultaneously allows a more comprehensive diagnosis in a more timely manner. The detection of the familial chromosomal translocation may direct the investigation of other family members and permit to plan future pregnancies.