BGEN 3020 Lecture Notes - Lecture 25: Myotonic Dystrophy, Fragile X Syndrome, Glutamine
26 Oct 2018
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Lecture 8 trinucleotide repeat disorders october 9th 2018. Regions of trinucleotide repeats are found in coding and non-coding regions. Cagcagcagcagcagcagcag: (cag)n, codes for glutamine (q, polyglutamie tract (poly-q, poly-q found in proteins from flies to humans, when it gets too big it starts to cause problems. Aggregation: normally glutamine shows up in many proteins, nobody knows what the poly-q"s role is. Can be found in coding or non-coding regions. Increased expansion of the repeats = increased expression and/or severity of the disorder: mechanism is expansion of the repeats. These are dynamic mutations: it is very rare to return things to normal would need a lucky deletion in the right place. Polymerase slippage: repeat region, dna pol slips backwards and creates a loop, as the repeat grows, the likelihood of it occurring again increases. Occurs due to rare looping of repeat regions during replication. The longer the repeat, the more likely it is to loop (and thus to increase in size)
