[Greg H]

Hey LBrown!

LisaV and other have given you good info. I just thought I'd add that, basically, when we are talking about bone marrow failures diseases, a "clone" is a blood-producing (hematapoietic) stem cell.

These stem cells are where the whole process of making blood starts. When they divide in order to multiply, they can either start a process that while make a cell that will develop into a blood cell that will circulate in your veins and arteries OR they can make an exact duplicate of themselves -- a clone -- which can then later clone itself, and so on. (It's more complicated than this, I'm sure, but that the basic version that I can understand.)

So, if you have a messed up stem cell (say, one missing the long arm of Chromosome 5) it can eventually clone more and more stem cells that are also missing the long arm of Chromosome 5. The ability of these defective cells to clone themselves is what makes MDS a "clonal" disorder.

Hope that's useful.

Take care.

Greg