NCCN Guidelines for Patients® | Myelodysplastic Syndromes

9 NCCN Guidelines for Patients ® : Myelodysplastic Syndromes, 2018 1 Myelodysplastic syndromes MDS basics Illustration Copyright © 2017 Nucleus Medical Media, All rights reserved. Figure 2 Chromosomes and genes in cells Genes are coded instructions in cells for making new cells and controlling how cells behave. Genes are a part of DNA, which is bundled into long strands called chromosomes. Every cell has 23 pairs of chromosomes. Blood stem cells go through a series of changes as they grow and develop into new blood cells. Blast cells are new, very young (immature) blood cells that grow into adult (mature) blood cells over time. Once they mature even a little, blast cells commit to become specific different types of mature blood cells. When they become completely mature, the blood cells leave the bone marrow and enter the bloodstream. MDS basics Cancer is a disease in which normal cells stop following the rules that let them grow up. MDS is a group of cancers that affect blood cells in the bloodstream and bone marrow. MDS starts in the blood-forming cells (blood stem cells) of the bone marrow. Normal blood stem cells grow and then divide to make new red blood cells, white blood cells, and platelets as the body needs them. Normal red blood cells live for 3 months, normal white blood cells (neutrophils) live for 8 to 14 days, and normal platelets live about a week. After the cells reach these ages, they die off and are replaced with new cells that are born from the bone marrow. If the cells are damaged, they die. New blood cells are then made to replace the old ones.