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Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Various banding techniques are used to visualize the chromosomes. The most frequently used method is Giemsa banding or G-banding, which results in a specific pattern of dark and light bands on each chromosome. The older method, quinacrine banding, or Q-banding, produces the same dark and light patterns, but requires the use of a fluorescence microscope and is not used routinely. Reverse banding or R-banding, results in the opposite of the dark and light pattern seen with G-banding; this may be used to better see the ends of the chromosomes. C-banding stains the constitutive heterochromatin, which is near the centromeres and NOR stain visualizes the nucleolar organizing regions of the satellites and stalks of acrocentric chromosomes. For routine karyotype analysis, G-banding is typically used by most laboratories. Routine karyotyping cannot detect gains or losses of cytogenetic material smaller than about 4Mb in size and therefore can miss significant abnormalities.
Oncogenes and Cancer
Published in Pimentel Enrique, Oncogenes, 2020
The variants of Ph chromosome in human CML may be divided in two groups, namely, “simple” translocations, involving chromosome 22 and another chromosome than 9, and complex (three- or four-way) translocations, involving chromosomes 9, 22 and at least one other chromosome. Using high resolution R-banding methods and in situ molecular hybridization techniques, it has been demonstrated that c-abl sequences are present in all Ph chromosome variants where a segment of chromosome region 9q34 is translocated to the Ph chromosome.173 These results lend support to the hypothesis that “translocation of the c-abl proto-oncogene to a specific region of chromosome 22 is essential for the development of CML”.173
Clinical and molecular characteristics of acute myeloid leukemia and the dismal prognosis of TP53 mutations in a real-world setting
Published in Hematology, 2023
Hong Liu, Yuye Shi, Shandong Tao, Yunjie Li, Chunling Wang, Liang Yu
Morphological, immunological, cytogenetic, and molecular biological examinations were performed at the initial diagnosis of AML. Real-time quantitative polymerase chain reaction (RT-qPCR, ELISA Kit) was used to screen 45 common fusion genes, including CBFB-MYH11, BCR-ABL1, RUNX1-RUNX1T1, and other gene fusions involving ETV6 (ETS variant 6), MLL (mixed lineage leukemia), and HOX family members. Cytogenetic examination was performed with conventional karyotyping (R-banding). According to the International System for Human Cytogenomic Nomenclature (ISCN 2020), clonal structure and numerical chromosome abnormalities were reported. Molecular abnormalities were detected by NGS using a 15-gene panel at the time of initial diagnosis. The 15-gene panel included FLT3 (fms-like tyrosine kinase 3), NRAS (neuroblastoma RAS viral oncogene homolog), C-KIT (KIT proto-oncogene receptor tyrosine kinase), WT1 (Wilms tumor 1), TET2 (tet methylcytosine dioxygenase 2), IDH1 (isocitrate dehydrogenase 1), IDH2 (isocitrate dehydrogenase 2), DNMT3A (DNA methyltransferase 3a), ASXL1 (additional sex combs like 1), NPM1 (nucleophosmin 1), CEBPA (CCAAT/enhancer binding protein a), RUNX1 (runt-related transcription factor 1), PHF6 (PHD finger protein 6), SF3B1 (splicing factor 3b subunit 1), and TP53. DNA was sequenced using a Nextseq550 system (NextSeq Sequencer, America) with probe capture and database building, with an average sequencing depth ≥1000×.
Molecular genetic and clinical characterization of acute myeloid leukemia with trisomy 8 as the sole chromosome abnormality
Published in Hematology, 2022
Jie Liu, WenMin Han, Xiaohui Cai, Zheng Wang, LiuJun Cao, HaiYing Hua, ZhuXia Jia, HongYing Chao, XuZhang Lu, HongJie Shen
Cytogenetic analyses using standard G or R-banding techniques were performed on bone marrow (BM) samples as part of the diagnostic work-up. Karyotyping results were described according to the International System for Human Cytogenetic Nomenclature (ISCN) 2005 [19]. Fluorescence in situ hybridization (FISH) analysis was performed using dual color, break apart probes for detection of rearrangements of KMT2A (MLL), and dual color, dual fusion probe set for detection of t(8;21)/RUNX1T1-RUNX1 fusion, following standard laboratory procedures. A total of 200 cells were counted. 41 fusion genes were detected by multiple reverse transcription PCR amplification, which was performed as 8 parallel multiplex reactions on 7500 Real-time PCR System (Applied Biosystems), as previous report [20].
Complex translocation leading to13q interstitial deletion in a Moroccan child with retinoblastoma and intellectual disability
Published in Ophthalmic Genetics, 2022
Zhour EL Amrani, Siham Chafai Elalaoui, Wafae Jdioui, Aziza Sbiti, Ilham Ratbi, Thomas Liehr, Abdelaziz Sefiani, Abdelhafid Natiq
Patient’s parents gave informed consent for this study, which was performed in accordance with the Declaration of Helsinki protocols and approved by the local institutional review boards. Venous blood (3 to 5 ml) acquired in a heparinized tube was taken of the patient and his parents for cytogenetic and molecular cytogenetic studies. Chromosomal analysis was performed by R-banding at the resolution level of 400 bands according to standard methods. Chromosome classification and analysis was performed using a semi-automatic system “Applied Imaging Cyto Vision TM 36”. Thereafter, fluorescence in situ hybridization (FISH) technique was done, applying home made whole chromosome painting probes and a commercially available probe for RB1 gene (Abbott, Vysis, Düsseldorf, Germany) (5). Probes used are summarized in Table 1. FISH was done according to standard procedures.