Stem Cell Mutations

At least since 1971, when Alfred Knudson proposed the “multiple hit” theory for the origin of cancers, investigators have supposed that an accumulation of random and inherited mutations explain malignancy.  However, in studying the DNA sequences of bone marrow stem cells from people of different ages, geneticists at Washington University (St. Louis, MO) found that by age 50, a person may have experienced about 500 hematopoietic cell mutations, and sorting those out between patients with acute myeloid leukemia and others of the same age without cancer is highly problematic, though they did find a number of “driver” and “cooperating” mutations.  And, in a related piece, Stanford researchers determined that individual sperm cells from the same male had different mutations that contribute to genetic individuality. ARTICLE ONE and ARTICLE TWO

Image Credit: Joshua McMichael, The Genome Institute and ScienceDaily.com