Term
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Definition
Most common genetic test
Discovered Downs and Philadelphia |
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Term
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Definition
Fluorescent is situ hybridization
Can be done in interphase - not restricted solely to metaphase |
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Term
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Definition
Can detect interphase aneuploidys
Used with populations of cells that have low mitotic index - ie BMT patient, chemotherapy, fixed tissues such as tumors, |
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Term
| Locus specific FISH probes |
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Definition
Can detect microdeletion syndromes such as DiGeorge, Williams, PWS/AS, velocardiofacial syndrome
Deletions of <1Mb that would not be detected on high resolution G banding |
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Term
| Sub-telomeric FISH probes (telomeric) |
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Definition
Detects unique telomeric region on a chromosome - this area has highest concentration of genes so deletions/duplications have very severe phenotypic effects
This region is not well identified with G banding because all telomeres have a light region
Subtelomeric rearrangements have been found in 4-9% of patients with idiopathic MR |
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Term
| Whole chromosome painting |
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Definition
| Used to detect translocations between different chromosomes |
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Term
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Definition
10X more common in mentally subnormal populations
Extra chunk of chromosome found in karyotype
1/3-1/2 are inherited
If not inherited and forms ring, then 30% chance of abnormalities |
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Term
| Comparative genomic hybridization (CGH) |
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Definition
Used to evaluate chromosome gains, losses, and aneuploidys
Does not need to be in metaphase
Uses control DNA + patient DNA and combine with selected sequences to evaluate a ratio
If ratio of patient DNA:control DNA is greater than 1.2 then there is gain of that gene in the patient; if less than 0.8 then deletion
Takes 1 week to evaluate |
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Term
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Definition
translocation of 9 and 22 which leads to fusion of BCR and ABL genes
Found in CML, AML, and ALL
These diseases can be treated with Imatinib (Gleevec) but only if Philadelphia chromosome is present (importance of genetic testing) |
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Term
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Definition
| Translocation of 8 and 14 which results in fusion of IgG heavy chain and myc oncogene |
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Term
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Definition
Implicated in some breast cancers
Can be treated with Herceptin if this is present |
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