• Mosaicism: the presence of two or more populations of cells within an organism, each with a different genetic composition
  • Somatic mosaicism affects the cells forming the body, causing disease manifestations to develop in affected individuals. 45,X/46,XX is the most commonly diagnosed mosaicism affecting sex chromosomes. These patients typically have a milder form of Turner syndrome or can be asymptomatic, depending on the ratio of abnormal to normal cells.
  • Germline mosaicism affects the cells that give rise to gametes, allowing the affected genes to pass to the offspring. The chance of a child being affected depends on the proportion of gametes that carry the mutation. When mosaicism is limited to the germline, the affected parent does not develop clinical manifestations.