IMED2004 Study Guide - Final Guide: Turner Syndrome, Housekeeping Gene, Delayed Puberty
Document Summary
Post-zygotic mutations resulting in two or more genetically distinct cell lines. A cell mutating early in development will have descendants in many tissues. A mutation arising later will be more localised. Mix of cells producing normal & abnormal proteins. Phenotype depends on proportion and distribution of cells producing abnormal protein. The earlier you have this mosaic expression. The more cells in organism will have that different expression set. The mosaic person producing the good protein. Will have a less severe phenotype than someone who has completely lost that gene function. Results in female with underdeveloped sex organs. Usually sterile, also know as turner"s syndrome. It is the only known viable monosomy in humans. Phenotype usually correlates with relative proportion of 45,xo cells. Postulated that live-born individuals with turner syndrome are cryptic mosaics. As most 45,x do not survive gestation. Depends when in developmental stage you get non disjunction. To ensure correct dosage of x-linked genes.
