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2014-05-19 01:01:08
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  1. What is clinical cytogenetics? Congenital vs Aquired?
    • The study of the relationship between human disease and chromosome alterations.
    • Congenital: chromosome changes at birth (but not genetic).  May result in mental retardation and abnormal physical appearance.
    • Aquired: result of cancers or leukemias
  2. What are the four types of specimens commonly used in cytogenetic analysis?  What are they used for (examples)?
    • **studies require VIABLE cells capable of undergoing cell division
    • Peripheral blood (NaHeparin): newborns with MCA, habitual abortion couples suspected of genetic abnormalities
    • Amniotic fluid: prenatal genetic diagnosis (AMA, NTD, or history of chr abnormalities)
    • Bone marrow: cancers and leukemias (chr abnormalities are nonrandom in these cases)
    • Solid tissue: fetal tissues (products of conception, skin punch biopsies, solid tumors)
  3. What is the best mitotic stage to study chromosomes? Why?
    • Prophase or metaphase
    • Chromosome morphology is only visualized during mitotic division
  4. Describe the harvest procedure in analysis of cytogenetic specimens
    • Colcemid: inactivates spindle formation, arresting cells at metaphase
    • Hypotonic solution: causes WBCs to swell, lyses RBCs
    • Fixative: Dehydrates/kills cells, hardens the nuclei
    • Slide making: solution placed on slides, allowed to dry
  5. What are the various cytogenetic staining techniques with a brief description
    • Pre-banding: very easy to make mistakes before any banding techniques were available
    • G-banding (trypsin): the "standard" banding we use
    • Fluorescence In-Situ Hybridization (FISH): DNA probe which hybridizes a specific region on a chromosome
    • used to detect Trisomy/aneuploidy, marker chromosomes, deletions/duplications/translocations
    • Spectral Karyotyping (SKY): each chromosome is stained a different color
    • Cytogenomic Microarray (CMA): arrayed series of thousands of microscopic spots of DNA oligonucleotides (features)
  6. Describe a normal karyotype
    • Arrangement of chromosomes from an individual arranged in pairs in descending order of size
    • 1 to 22 + X/Y
  7. What are the autosomal and sex chromosome abnormalities with a brief description?
    • Trisomy 21: down syndrome
    • flat face, protruding tongue, cardiac defects, mental retardation
    • Trisomy 18: Edward's syndrome
    • Trisomy 13: patau syndrome
    • cleft lip, polydactyly, severe mental retardation
    • 45, X: Turner's syndrome
    • no secondary sex characteristics, edema, gonadal dysgenesis
  8. Describe Burkit's lymphoma generally, morphologically, immunologically and cytogenetically.
    • Aggressive B cell lymphoma
    • Typically in children
    • African presents with mass in jaw, associated with EB virus.
    • American presents with abdominal mass.
    • Morphologically: Monotonous proliferation of cells (cobblestone pattern)
    • "Starry sky" appearance
    • Deeply basophilic cytoplasm with multiple vacuoles
    • Immunologically: CD19+ and CD10+
    • Cytogenetically: 46,XY in marrow
    • t(8;14) is characteristic
  9. Describe how CML and Mantle Cell Lymphoma can exist and be diagnosed in the same patient
    • Mantle Cell Lymphoma caused by chemo
    • 7 - 10% of NHL
    • Characterized by t(11;14)