SNP Shot: Genomic Insights

Chronic myeloid leukemia (CML) is a slowly progressing cancer that affects the bone marrow, the tissue responsible for creating blood cells. Healthy bone marrow produces red blood cells (erythrocytes) for oxygen transport, white blood cells (leukocytes) to fight infections, and platelets (thrombocytes) for blood clotting. In CML, the bone marrow produces an excessive number of white blood cells. In the early stages, these cells may function relatively normally. However, as CML progresses, immature white blood cells, known as myeloblasts or blasts, build up in the blood and bone marrow. This overproduction of myeloblasts disrupts the development of other blood cells, resulting in a deficiency of red blood cells (anemia) and platelets.

CML typically develops after the age of 60. Common symptoms include extreme tiredness (fatigue), fever, and unintentional weight loss. Many individuals with CML experience an enlarged spleen (splenomegaly), which can cause abdominal fullness and decreased appetite. Notably, approximately half of individuals with CML are initially asymptomatic and are diagnosed incidentally during blood tests conducted for unrelated reasons.

CML progresses through three distinct phases: the chronic phase, the accelerated phase, and the blast phase (or blast crisis). During the chronic phase, there is an elevated count of mature white blood cells, and myeloblasts constitute less than 10% of the blood cells. Symptoms during this phase are usually mild or absent and worsen gradually over months to years. The accelerated phase is characterized by a slightly higher proportion of myeloblasts, ranging from 10 to 29% of blood cells. The signs and symptoms continue to intensify, and this phase typically lasts 4 to 6 months, although some individuals may not experience it. In the blast crisis phase, myeloblasts account for 30% or more of the cells in the blood or bone marrow. This phase is marked by the most severe symptoms, including a significantly enlarged spleen, bone pain, and weight loss. Life-threatening complications, such as serious infections and uncontrolled bleeding, can occur.

Inheritance:

CML is typically not passed down from parents to children. It arises from a genetic change, called a somatic mutation, within the body's cells after fertilization.