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Central Nervous System
Published in Pat Price, Karol Sikora, Treatment of Cancer, 2020
ATRTs are rare, malignant embryonal tumors, usually arising in the posterior fossa of children, especially infants less than 3 years, accounting for 1–2% of brain tumors in children. Histopathologically, they show rhabdoid cells, often together with cells resembling medulloblastoma. In the great majority of cases, alteration of the locus of the tumor suppressor gene SMARCB1 (a member of a chromosome remodeling complex) on the chromosome band 22q11.2 is a hallmark genetic aberration. A significant proportion of these patients have germline mutations in SMARCB1 or SMARCA4, associated with a potentially aggressive disease course. Recent analysis of genomic data has suggested three sub-groups of ATRT based on methylation profiles.
Molecular Approaches Towards the Isolation of Pediatric Cancer Predisposition Genes
Published in John T. Kemshead, Pediatric Tumors: Immunological and Molecular Markers, 2020
It is conceivable, although unlikely, that these walking strategies can be used to cover the distance from catalase or FSH to the Wilms’ locus (see Figure 12). The large physical distance between even closely linked loci, however, is a major problem. The human haploid genome contains 3 × 109 bp of which, for example, chromosome 11 constitutes 2.4%, i.e., 7.8 × 107 bp. Chromosome band 11p13 (about 4% of the chromosome)contains 3 × 106 bp or 3000 kb. Using cosmid cloning strategies, 45 kb is the largest amount of DNA that can be cloned. To isolate region 11p13, 70 contiguous cosmids would have to be isolated which represents a formidable task even if the libraries are fully representative.106.
Thrombocytopenia-Absent Radius
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
As TAR shows autosomal recessive inheritance, prenatal diagnosis and preimplantation testing may be offered to prospective parents carrying 200-kb or 500-kb deletion at chromosome band 1q21.1, and/or R8BM8A hypomorphic allele [16].
Learning about quantitative genetics from Marla Sokolowski
Published in Journal of Neurogenetics, 2021
Localizing genes for quantitative traits by conventional recombination mapping is always a formidable challenge because environmental variation, minor genes, and genetic markers have modifying effects on continuously varying phenotypes such as foraging. To compensate for this, de Belle and colleagues used ‘lethal tagging’ and deletion mapping to localize the gene to the left arm of chromosome 2. This involved generating radiation-induced lethal alleles that would fail to complement the recessive sitter phenotype. The result provided a salivary-chromosome-band level of resolution. The last necessary link came from seeing in the literature that the structural locus for one of the two cGMP-dependent protein kinases in Drosophila (dg2) mapped to the same salivary chromosome band (Kalderon & Rubin, 1989) as foraging.
Complex chromosomal aberrations in a fetus originating from oocytes with smooth endoplasmic reticulum (SER) aggregates
Published in Systems Biology in Reproductive Medicine, 2018
Ioannis A. Sfontouris, George T. Lainas, Tryfon G. Lainas, Efthimios Faros, Maria Banti, Katerina Kardara, Katerina Anagnostopoulou, Harris Kontos, George K. Petsas, Efstratios M. Kolibianakis
Array-CGH was performed on uncultured amniocytes using the CytoChip Focus Constitutional BAC array (v1.1) (BlueGnome Ltd, Cambridge, UK) with a resolution of 1Mb. Arrays were analyzed using InnoScan 700 scanner (Arrayit Corporation, Sunnyvale, USA) and BlueFuse Multi software (v3.1) (BlueGnome Ltd, Cambridge, UK). The chromosome positions were given according to the human genome assembly GRCh 37 (hg19). Array-CGH revealed a 7632-Mb deletion at chromosome band 2q31.1q32.1 (175,428,717–183,060,453 bp) (Figure 2). The most distal normal probes were at chromosome position 173,542,101 and 184,711,524 upstream and downstream, respectively. There are 36 OMIM genes mapped in the deleted segment, including the homeobox D (HOXD) cluster that plays a key role in embryonic limb development (Goodman 2002). No aneuploidies were detected.
ASXL1 mutations in myeloid neoplasms: pathogenetic considerations, impact on clinical outcomes and survival
Published in Current Medical Research and Opinion, 2018
Juliana Alvarez Argote, Constantin A. Dasanu
ASXL1 comprises 13 exons located in chromosome band 20q11. It encodes a member of the polycomb family of the chromatin binding proteins and is involved in epigenetic regulation of gene expression via its C-terminal plant homeodomain (PHD) finger (Figure 1)6. Although the PHD finger is located within the exon 12 of ASXL1, it is important to recognize that it represents just a small portion of the exon 12. The PHD finger interacts with the polycomb group repressive complex protein (PRC1 and PRC2) and other transcription activators and repressors to exert its function in regulating chromatin17–21. Data suggests that ASXL1 mutations associated with myeloid neoplasms display a truncation in exon 12, adjacent to the PHD finger22–24. In addition, in vitro studies in leukemic cells suggest that there is a loss of ASXL1 protein expression when ASXL1 mutations are detected in myeloid neoplasms24. The most common ASXL1 mutation found in patients with myeloid neoplasms is c.1934dupG;p.G646WfsX12 that accounts for more than 50% of cases17–19,25.