TY - CHAP M1 - Book, Section TI - Telomere Disease A1 - Calado, Rodrigo T. A1 - Young, Neal S. A2 - Jameson, J. Larry A2 - Fauci, Anthony S. A2 - Kasper, Dennis L. A2 - Hauser, Stephen L. A2 - Longo, Dan L. A2 - Loscalzo, Joseph Y1 - 2018 N1 - T2 - Harrison's Principles of Internal Medicine, 20e AB - In telomere diseases (also called telomeropathies or telomere spectrum disorders), organ dysfunction is caused by loss of the ends of chromosomes, a process termed accelerated telomere attrition. Inadequate repair or insufficient protection of telomeres and their resulting erosion induces cell death, deficient cell proliferation, and chromosome instability; affected tissues show defective organ regeneration, fibrosis or replacement by fat, and a proclivity for cancer. A variety of regenerative disorders affecting especially the bone marrow, lungs, liver, and skin share telomere dysfunction and loss as their common molecular mechanism. It is important to note that telomeres appear to shorten with time based on cross-sectional data of average telomere length in groups of people at different ages. However, limited data exist about telomere shortening longitudinally in individual people. Despite shortening of telomeres over time, normal aging is not associated with the development of disease from short telomeres. In normal aging, sufficient stem cell number and function are maintained to sustain vital processes. Even a patient who receives a limited number of hematopoietic cells from an adult donor is capable of maintaining normal hematopoiesis for many years, at least in part related to normal telomerase function and telomere repair. When symptoms develop as a consequence of short telomeres, a disease process is at work. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/16 UR - accessmedicine.mhmedical.com/content.aspx?aid=1156521774 ER -