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The laboratory basis of medical genetics
Published in Peter S. Harper, The Evolution of Medical Genetics, 2019
Following the development of chromosome banding, a later technique that would help to bridge cytogenetics and human molecular genetics was in situ hybridization, initially using autoradiography to detect radioactive probes for repetitive DNA sequences, by Pardue and Gall (1970) in America, then progressively refined to detect single copy sequences, using fluorescent rather than radioactive labels. Multiple probes allowed ‘chromosome painting’, pioneered by Malcolm Ferguson-Smith and colleagues, by now based in Cambridge; this proved especially useful in comparative cytogenetic studies of different species, where patterns of chromosome segment rearrangement could often indicate their evolutionary lineage. Ferguson-Smith (2015) has outlined the successive developments in this transition period.
Chromosome abnormalities
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Rearrangement of genetic material within a chromosome is usually recognised by chromosome banding techniques but is also revealed by whole genome sequencing. When the rearrangement is confined to one arm of a chromosome (paracentric inversion), the risk of abnormality in the offspring is small (3% has been suggested). However, if the centromere is involved (pericentric inversion) in an autosome, this may cause problems in pairing with the homologous chromosome at meiosis, so that gametes with an unbalanced chromosome complement may be formed. This may be discovered in a parent after a child with an unbalanced chromosome abnormality has been born, or it may be an incidental finding.
Cytogenetics of Colorectal Cancer
Published in Leonard H. Augenlicht, Cell and Molecular Biology of Colon Cancer, 2019
Cytogenetic abnormalities have long been observed in animal and human cancers and play an important role in neoplastic transformation and tumor progression. The discovery of the Philadelphia (Ph) chromosome as a deleted G-group chromosome1 and later as a translocation between chromosome 9 and 22 in chronic myelogenous leukemia (CML)2 served as the cornerstone for specific chromosome abnormality associated with a particular human neoplasm. Nonrandom chromosome anomalies (reciprocal translocation, deletion, and inversion) are now well established in different leukemias and lymphomas. This progress in the field of cytogenetic oncology has been made possible through the development of chromosome banding techniques that have aided in the identification of not only the entire chromosome, but even a small segment of a chromosome.3
An interview on rare and genetic diseases with Dr Bruce Korf, Associate Dean for Genomic Medicine at the University of Alabama at Birmingham
Published in Current Medical Research and Opinion, 2022
I began working in human genetics as an undergraduate in 1970. This was still in the early days of clinical cytogenetics when chromosome banding techniques were just being introduced. It was during my genetics training that molecular diagnostic testing first became clinically available. By the time I began my career as a faculty member, fluorescence in situ hybridization was being introduced and the age of gene discovery had begun. Now we are in an era of genome sequencing, where it is possible to make precise diagnoses that we would never have imagined ten years ago. We are also making inroads into the genetic contributions to common multifactorial disorders, with the hope that this will enable identification of individuals at risk of disease so that preventative strategies can be instituted. Finally, therapeutics are being developed for both rare and common disorders, as well as cancer, that would not have been possible without recognition of the genetic contributions to these disorders. Human genetics has seen a continuing series of technological and conceptual advances that have increasingly been incorporated into medical practice.
Why classical cytogenetics still matters in acute myeloid leukemia
Published in Expert Review of Hematology, 2020
Vladimir Lj Lazarevic, Bertil Johansson
Cytogenetic analyses were already performed on acute myeloid leukemia (AML) cases in the 1960s. At that time, however, these investigations were hampered by the lack of chromosome banding techniques, restricting the analyses to merely counting the chromosomes and identifying large structural chromosome changes. This dramatically changed when chromosome banding methods were introduced in the early 1970s [1]. Within just a few years, a large number of chromosomal aberrations were detected in AML, such as t(8;21)(q22;q22) [the first AML-specific translocation identified], inv(3)(q21q26), monosomy 5/del(5q), t(6;9)(p22;q34), monosomy 7/del(7q), trisomy 8, t(15;17)(q24;q21), and complex karyotypes (CK), to name but a few. In parallel with the increasing number of AML-associated abnormalities reported in the following decade, it became apparent that many of them were associated with certain, sometimes characteristic, morphologic, immunophenotypic, and clinical features [2,3]. Today, identification of several specific chromosomal changes is essential for proper risk stratification, and, hence, for treatment decision. For example, some aberrations in AML are associated with a favorable outcome, such as t(8;21) and inv(16), and others with a dismal prognosis, such as inv(3), CK, and monosomal karyotype (MK) [2,4].
Coexisting driver mutations in MPN: clinical and molecular characteristics of a series of 11 patients
Published in Hematology, 2018
L. De Roeck, L. Michaux, K. Debackere, E. Lierman, P. Vandenberghe, T. Devos
Eleven MPN patients with coexisting driver mutations were identified at the University Hospitals of Leuven by cytogenetic and molecular analysis between 1994 and 2017. We retrospectively studied the patient characteristics of these 11 patients including age at diagnosis, disease-related symptoms and clinical characteristics, as well as treatment, treatment response and toxicity. Furthermore, we analysed the cytogenetic abnormalities and molecular analyses of these patients and the evolution during follow-up. The diagnosis of CML was made by chromosome banding analysis, supplemented if needed by interphase fluorescence in situ hybridization (FISH). The JAK2 allele burden (% JAK2 V617F-mutated cells) was assessed by quantitative PCR on DNA enhanced from peripheral non-fractionated leukocytes. The CALR mutation was identified by means of Sanger sequencing. All data were collected from the electronic medical records of our institution and five other hospitals (OLV Aalst, ZOL Genk, Clinique St-Luc Bouge, AZ Sint-Maarten Duffel, AZ Damiaan Oostende). Three patients died during follow-up.