Restriction fragment length polymorphisms

[alexandertg6]

I know RFLPs are variable regions in the DNA molecule, but i dont understand really what they are or how they can be useful in genotyping disease with the use of restriction enzymes or how genotyping them would work. also why can you get a blot on gel after digestion with an enzyme like EcoR1 that shows that an individual has the variant or diseased DNA without that person actually having it?

thanks,
Alex

[canalon]

RFLPs are no regions. It stands for Restriction Fragment Length Polymorphism. In short you PCR amplify a region wher you suspect there is variabilty, then digest the PCR product. The mutation will change the restriction site and change the length of the product, so the profile will change.