Cancer cytogenetics

• tumoral tetrasomies
  20 June 2016

  Examples
  Tetrasomy for diagnosis of urothelial carcinoma https://twitter.com/Pathologists/status/744606179872014336
  See also
  tumoral chromosomal anomalies

• BCR/ABL1 testing
  5 January 2014
• tumoral genomic losses affecting noncoding genes
  29 August 2008

  Cancer-associated chromosomal losses may act through inactivation of genes that do not encode proteins. For example, several genomic regions that are recurrently deleted in a variety of tumors contain microRNA genes (miRNAs).
  These genes encode small RNAs (sRNAs) involved in post-transcriptional regulation of gene expression, and there is growing evidence that the loss of specific microRNAs with tumor-suppressive activity may contribute to tumorigenesis.
  This pathogenetic mechanism was (...)

• tumoral genomic losses resulting in allelic insufficiency
  29 August 2008

  Chromosomal deletions can cause tumorigenesis by inactivation of a single allele.
  Since such haplo-insufficient tumor-suppressor genes cannot be identified through analysis of the remaining allele, alternative approaches are required to assess the consequences of monoallelic deletion.
  An example is a recent study in which graded down-regulation of multiple candidate genes by RNA interference was used to identify RPS14 as a causal gene for the 5q minus syndrome, a subtype of the (...)

• large-scale genomic losses
  29 August 2008

  Extensive genomic deletions affecting multiple genes are frequent in tumors, making it difficult to identify which lost gene contributes to the development of the cancer.
  The classic approach to identifying a tumor-suppressor gene compares multiple tumors with a specific chromosomal deletion to determine the minimal genomic region that is lost in all cases.
  Candidate genes from this region are then screened for deletions, mutations, or epigenetic modifications that inactivate the (...)

• genomic losses
  29 August 2008

  The spectrum of genomic losses ranges from cytogenetically visible alterations, such as complete or partial chromosomal monosomies (large-scale genomic losses), to small regional deletions or single-gene or intragenic deletions that are detectable only by techniques that provide high spatial resolution (small genomic losses).
  Most recurrent genomic losses probably contribute to malignant transformation by reducing the function of specific genes in the affected chromosomal regions.
  Since (...)

• focal genomic gains
  29 August 2008

  Gains affecting small genomic regions or even single genes have been described less frequently than large gains.
  However, it is now possible to identify focal gains by scanning cancer genomes for variations in DNA copy numbers with new high-resolution methods, such as comparative genomic hybridization (CGH) and single-nucleotide polymorphism (SNP) genotyping.
  Array-based CGH and SNP genotyping analyses, for example, have shown amplification of a small segment of band 6q25.1 containing the (...)

• large-scale genomic gains
  29 August 2008

  Large-Scale Genomic Gains commonly arise from chromosomal nondisjunction or unbalanced translocations, which cause complete or partial chromosomal trisomies, or from amplification events affecting DNA segments of different size.
  Numerous examples of large-scale genomic gains are associated with specific types of cancer. Since such aberrations involve multiple genes, the identification of their functionally relevant targets has proved to be difficult.
  One way to "filter" the genes within (...)

• genomic gains
  29 August 2008

  Most recurrent genomic gains probably contribute to tumorigenesis by enhancing the activity of specific genes in the affected chromosomal regions.
  Types
  large-scale genomic gains
  focal genomic gains
  Large-Scale Genomic Gains
  Genomic gains commonly arise from chromosomal nondisjunction or unbalanced translocations, which cause complete or partial chromosomal trisomies, or from amplification events affecting DNA segments of different size.
  Numerous examples of large-scale genomic (...)

• tumoral chromosomal rearrangements
  29 August 2008

  Reciprocal translocations, inversions, and insertions are typical chromosomal rearrangements. There is substantial evidence that these alterations are early or even initiating events in tumorigenesis.
  For instance, certain translocations that are associated with childhood leukemia arise in utero, years before the appearance of overt disease.
  Furthermore, most chromosomal rearrangements are closely associated with specific tumor types, even though individual genes — such as MLL, ETV6, and (...)

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