Prenatal - PRENATAL DETECTION OF GENE DEFECTS Prenatal...

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PRENATAL DETECTION OF GENE DEFECTS • Prenatal detection and heterozygote screening amniocentesis fetal cells collected at approx. 13 wks chorionic villus sampling ( CVS ) samples collected at 8 weeks fetal cell sorting: rare fetal cells in mothers blood separated on a "flow-cell" machine • Defects detectable from fetal cell samples: - chromosome aberrations (Down's etc) - enzymes or gene products (Tay-Sachs, etc) - DNA changes (sickle cell etc) - RFLPs; can link a restriction pattern to presence of defective allele -allele-specific probes can hybridize only if an exact 19 base complement is present DNA AMPLIFICATION - PCR ( Polymerase Chain Reaction ) allows faster, more precise tests TAQ DNA polymerase is from Thermus aquatus (hot springs) bacteria, so can function at high temperatures without being denatured. Technique: • Add excess of short (19-26 bases) single-stranded primers that flank the target sequence and are complementary to opposing strands, • Heat DNA to 95° to melt into single strands
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Prenatal - PRENATAL DETECTION OF GENE DEFECTS Prenatal...

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