What is hyperdiploid and hypodiploid myeloma?

In a previous Health Tree University lesson, we explored how multiple myeloma can be classified into six distinct genetic subtypes. Now it's time to take a closer look at one in particular, hyper diploid myeloma. In this lesson, we'll dive deeper into what sets this subtype apart, how it impacts disease progression, and what it means for treatment and prognosis. What is hyper diploid and hypodyploid myeloma? Hi, I'm Dr. Tara Gregory from the Colorado Blood Cancer Institute in Denver, Colorado. One of the big areas that we're looking at in multiple myeloma is understanding more about the DNA changes that we can see in the myeloma cells. So these aren't changes that we see in the healthy cells, the healthy bone marrow cells, These are specific to the myeloma cancer cells. And when patients have extra copies of DNA, then we call that hyper diploid. And if we see less copies of DNA or less chromosomes, we call that hypodyploid. And what we have known for quite some time is that patients who have hyper diploid tend to do better with their myeloma or their MGUS risk of progression versus patients who have hypodyploid or less DNA in those cancer chromosomes. How are hyper diploid and hypodyploid multiple myeloma detected? Hyper diploid means that when we look at a cell, we look at 20 of the chromosomes that are typically inside those cells, or 20 sets. And then we say, okay, is there any abnormality in those basic 20 cells that we're looking at? And when you're born, you get 23 chromosomes from mom and 23 chromosomes from dad. So there should be about 46 in each cell. So then we look at the 20 cells and say, is there anything different? In hyper diploid myeloma, typically what we see is that there is an extra copy of chromosomes 3, 5, 9, 11, and 15. I remember it as the odds minus the 13, because that's a little bit different in myeloma. On the flip side, sometimes when we look at just those 20 cells, some of the myeloma cells are missing full chromosomes, and we call that being hypodyploid. And typically patients who are hypodyploid have worse outcomes than patients who are hyper diploid. Every cell in the human body has 46 chromosomes, no more, no less. But that changes in cancer, because cancer is genetically unstable. Part of cancer is the loss of chromosomal material or acquisition of chromosomal material. And different cancer cells will have a different number of chromosomes. In some, they'll lose chromosomal material. So instead of having 46 chromosomes, they'll have 42 or 43 or 44. So they have a lower number, hypo, like hypothermia, low. And so they'll be hypodyploid. Diploid refers to 46 chromosomes. And it's been recognized that patients with hypodyploid myeloma, less than 46 chromosomes, have a much more serious prognosis than people of 46. Interestingly, if you gain chromosomes, and that could be 47, 48, but in fact, you can actually double the chromosome number from 46 to 92, which is called tetraploid, where 46 is called diploid, increased number of chromosomes, even though it's profoundly abnormal, does not have an adverse prognosis. It has a standard prognosis, maybe a slightly improved prognosis. So we do that by counting the amount of DNA that can be done by metaphase cytogenetics, or more commonly, flow studies allow us to detect the DNA content in cells very rapidly to determine if the amount of DNA is less than standard, hypodyploid, or more than standard, hyperdiploid.