BIOLOGY 2C03 Lecture Notes - Lecture 9: Wild Type, Genetic Screen, Mutation
23 Apr 2016
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Abnormalities do not appear until after organisms have had an opportunity to reproduce and transmit the mutation. Huntingtons disease: neuromuscular disorder, fatal within 10-15 yrs of diagnosis, Mutation to a gene on chromosome 4. Normal function of the wildtype gene is unknown. Trinucleotide repeat expansion disorder: cag trinucleotide encoding the aa glu: hotspot", regions that undergo a greater than average number of mutations, mechanism of mutatino: strand slippage, dna pol can occasionally slip backwards during the replication of repetivitve dna. Wt alleles have 2-28 repeats, hd with 28-35 do nto cause disease but these alleles are unstable. Those with more than 40 will develop hd anywhere from teens onwards. Pcr detects the number of repeats: primers binding to opposite sites of the cag repeat, dna fragments are aomplified and sepeaated by gel electrophoresis. Positional cloning in humans: mapping the hd gene:
